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> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="pt-sitesupport-2" class="user-links-collapsible-item mw-list-item user-links-collapsible-item"><a data-mw="interface" href="https://donate.wikimedia.org/wiki/Special:FundraiserRedirector?utm_source=donate&utm_medium=sidebar&utm_campaign=C13_en.wikipedia.org&uselang=en" class=""><span>Donate</span></a> </li> <li id="pt-createaccount-2" class="user-links-collapsible-item mw-list-item user-links-collapsible-item"><a data-mw="interface" href="/w/index.php?title=Special:CreateAccount&returnto=BIOS" title="You are encouraged to create an account and log in; however, it is not mandatory" class=""><span>Create account</span></a> </li> <li id="pt-login-2" class="user-links-collapsible-item mw-list-item user-links-collapsible-item"><a data-mw="interface" href="/w/index.php?title=Special:UserLogin&returnto=BIOS" title="You're encouraged to log in; however, it's not mandatory. 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data-event-name="pinnable-header.vector-toc.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-toc.unpin">hide</button> </div> <ul class="vector-toc-contents" id="mw-panel-toc-list"> <li id="toc-mw-content-text" class="vector-toc-list-item vector-toc-level-1"> <a href="#" class="vector-toc-link"> <div class="vector-toc-text">(Top)</div> </a> </li> <li id="toc-History" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#History"> <div class="vector-toc-text"> <span class="vector-toc-numb">1</span> <span>History</span> </div> </a> <ul id="toc-History-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-User_interface" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#User_interface"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>User interface</span> </div> </a> <ul id="toc-User_interface-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Extensions_(option_ROMs)" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Extensions_(option_ROMs)"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Extensions (option ROMs)</span> </div> </a> <button aria-controls="toc-Extensions_(option_ROMs)-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Extensions (option ROMs) subsection</span> </button> <ul id="toc-Extensions_(option_ROMs)-sublist" class="vector-toc-list"> <li id="toc-Physical_placement" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Physical_placement"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1</span> <span>Physical placement</span> </div> </a> <ul id="toc-Physical_placement-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Operation" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Operation"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Operation</span> </div> </a> <button aria-controls="toc-Operation-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Operation subsection</span> </button> <ul id="toc-Operation-sublist" class="vector-toc-list"> <li id="toc-System_startup" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#System_startup"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1</span> <span>System startup</span> </div> </a> <ul id="toc-System_startup-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Boot_process" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Boot_process"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.2</span> <span>Boot process</span> </div> </a> <ul id="toc-Boot_process-sublist" class="vector-toc-list"> <li id="toc-Boot_priority" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Boot_priority"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.2.1</span> <span>Boot priority</span> </div> </a> <ul id="toc-Boot_priority-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Boot_failure" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Boot_failure"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.2.2</span> <span>Boot failure</span> </div> </a> <ul id="toc-Boot_failure-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Boot_environment" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Boot_environment"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.3</span> <span>Boot environment</span> </div> </a> <ul id="toc-Boot_environment-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Operating_system_services" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Operating_system_services"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Operating system services</span> </div> </a> <button aria-controls="toc-Operating_system_services-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Operating system services subsection</span> </button> <ul id="toc-Operating_system_services-sublist" class="vector-toc-list"> <li id="toc-Processor_microcode_updates" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Processor_microcode_updates"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.1</span> <span>Processor microcode updates</span> </div> </a> <ul id="toc-Processor_microcode_updates-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Identification" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Identification"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.2</span> <span>Identification</span> </div> </a> <ul id="toc-Identification-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Overclocking" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Overclocking"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.3</span> <span>Overclocking</span> </div> </a> <ul id="toc-Overclocking-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Modern_use" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Modern_use"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.4</span> <span>Modern use</span> </div> </a> <ul id="toc-Modern_use-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Configuration" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Configuration"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>Configuration</span> </div> </a> <button aria-controls="toc-Configuration-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Configuration subsection</span> </button> <ul id="toc-Configuration-sublist" class="vector-toc-list"> <li id="toc-Setup_utility" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Setup_utility"> <div class="vector-toc-text"> <span class="vector-toc-numb">6.1</span> <span>Setup utility</span> </div> </a> <ul id="toc-Setup_utility-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Hardware_monitoring" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Hardware_monitoring"> <div class="vector-toc-text"> <span class="vector-toc-numb">6.2</span> <span>Hardware monitoring</span> </div> </a> <ul id="toc-Hardware_monitoring-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Reprogramming" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Reprogramming"> <div class="vector-toc-text"> <span class="vector-toc-numb">6.3</span> <span>Reprogramming</span> </div> </a> <ul id="toc-Reprogramming-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Hardware" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Hardware"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>Hardware</span> </div> </a> <ul id="toc-Hardware-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Vendors_and_products" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Vendors_and_products"> <div class="vector-toc-text"> <span class="vector-toc-numb">8</span> <span>Vendors and products</span> </div> </a> <ul id="toc-Vendors_and_products-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Open-source_BIOS_replacements" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Open-source_BIOS_replacements"> <div class="vector-toc-text"> <span class="vector-toc-numb">9</span> <span>Open-source BIOS replacements</span> </div> </a> <ul id="toc-Open-source_BIOS_replacements-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Security" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Security"> <div class="vector-toc-text"> <span class="vector-toc-numb">10</span> <span>Security</span> </div> </a> <ul id="toc-Security-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Alternatives_and_successors" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Alternatives_and_successors"> <div class="vector-toc-text"> <span class="vector-toc-numb">11</span> <span>Alternatives and successors</span> </div> </a> <ul id="toc-Alternatives_and_successors-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">12</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Notes" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Notes"> <div class="vector-toc-text"> <span class="vector-toc-numb">13</span> <span>Notes</span> </div> </a> <ul id="toc-Notes-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">14</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Further_reading" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Further_reading"> <div class="vector-toc-text"> <span class="vector-toc-numb">15</span> <span>Further reading</span> </div> </a> <ul id="toc-Further_reading-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> <span class="vector-toc-numb">16</span> <span>External links</span> </div> </a> <ul id="toc-External_links-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Toggle the table of contents" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Toggle the table of contents</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">BIOS</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. Available in 67 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-67" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">67 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-af mw-list-item"><a href="https://af.wikipedia.org/wiki/BIOS" title="BIOS – Afrikaans" lang="af" hreflang="af" data-title="BIOS" data-language-autonym="Afrikaans" data-language-local-name="Afrikaans" class="interlanguage-link-target"><span>Afrikaans</span></a></li><li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D8%A7%D9%84%D9%86%D8%B8%D8%A7%D9%85_%D8%A7%D9%84%D8%A3%D8%B3%D8%A7%D8%B3%D9%8A_%D9%84%D9%84%D8%A5%D8%AF%D8%AE%D8%A7%D9%84_%D9%88%D8%A7%D9%84%D8%A5%D8%AE%D8%B1%D8%A7%D8%AC" title="النظام الأساسي للإدخال والإخراج – Arabic" lang="ar" hreflang="ar" data-title="النظام الأساسي للإدخال والإخراج" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-az mw-list-item"><a href="https://az.wikipedia.org/wiki/BIOS" title="BIOS – Azerbaijani" lang="az" hreflang="az" data-title="BIOS" data-language-autonym="Azərbaycanca" data-language-local-name="Azerbaijani" class="interlanguage-link-target"><span>Azərbaycanca</span></a></li><li class="interlanguage-link interwiki-be mw-list-item"><a href="https://be.wikipedia.org/wiki/BIOS" title="BIOS – Belarusian" lang="be" hreflang="be" data-title="BIOS" data-language-autonym="Беларуская" data-language-local-name="Belarusian" class="interlanguage-link-target"><span>Беларуская</span></a></li><li class="interlanguage-link interwiki-be-x-old mw-list-item"><a href="https://be-tarask.wikipedia.org/wiki/BIOS" title="BIOS – Belarusian (Taraškievica orthography)" lang="be-tarask" hreflang="be-tarask" data-title="BIOS" data-language-autonym="Беларуская (тарашкевіца)" data-language-local-name="Belarusian (Taraškievica orthography)" class="interlanguage-link-target"><span>Беларуская (тарашкевіца)</span></a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/BIOS" title="BIOS – Bulgarian" lang="bg" hreflang="bg" data-title="BIOS" data-language-autonym="Български" data-language-local-name="Bulgarian" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-bs mw-list-item"><a href="https://bs.wikipedia.org/wiki/BIOS" title="BIOS – Bosnian" lang="bs" hreflang="bs" data-title="BIOS" data-language-autonym="Bosanski" data-language-local-name="Bosnian" class="interlanguage-link-target"><span>Bosanski</span></a></li><li class="interlanguage-link interwiki-br mw-list-item"><a href="https://br.wikipedia.org/wiki/BIOS" title="BIOS – Breton" lang="br" hreflang="br" data-title="BIOS" data-language-autonym="Brezhoneg" data-language-local-name="Breton" class="interlanguage-link-target"><span>Brezhoneg</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/BIOS" title="BIOS – Catalan" lang="ca" hreflang="ca" data-title="BIOS" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/BIOS" title="BIOS – Czech" lang="cs" hreflang="cs" data-title="BIOS" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-da mw-list-item"><a href="https://da.wikipedia.org/wiki/BIOS" title="BIOS – Danish" lang="da" hreflang="da" data-title="BIOS" data-language-autonym="Dansk" data-language-local-name="Danish" class="interlanguage-link-target"><span>Dansk</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/BIOS" title="BIOS – German" lang="de" hreflang="de" data-title="BIOS" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/Baasvahetuss%C3%BCsteem" title="Baasvahetussüsteem – Estonian" lang="et" hreflang="et" data-title="Baasvahetussüsteem" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-el mw-list-item"><a href="https://el.wikipedia.org/wiki/BIOS" title="BIOS – Greek" lang="el" hreflang="el" data-title="BIOS" data-language-autonym="Ελληνικά" data-language-local-name="Greek" class="interlanguage-link-target"><span>Ελληνικά</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/BIOS" title="BIOS – Spanish" lang="es" hreflang="es" data-title="BIOS" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-eo mw-list-item"><a href="https://eo.wikipedia.org/wiki/BIOS" title="BIOS – Esperanto" lang="eo" hreflang="eo" data-title="BIOS" data-language-autonym="Esperanto" data-language-local-name="Esperanto" class="interlanguage-link-target"><span>Esperanto</span></a></li><li class="interlanguage-link interwiki-eu mw-list-item"><a href="https://eu.wikipedia.org/wiki/BIOS" title="BIOS – Basque" lang="eu" hreflang="eu" data-title="BIOS" data-language-autonym="Euskara" data-language-local-name="Basque" class="interlanguage-link-target"><span>Euskara</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%A8%D8%A7%DB%8C%D9%88%D8%B3" title="بایوس – Persian" lang="fa" hreflang="fa" data-title="بایوس" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/BIOS_(informatique)" title="BIOS (informatique) – French" lang="fr" hreflang="fr" data-title="BIOS (informatique)" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-gl mw-list-item"><a href="https://gl.wikipedia.org/wiki/BIOS" title="BIOS – Galician" lang="gl" hreflang="gl" data-title="BIOS" data-language-autonym="Galego" data-language-local-name="Galician" class="interlanguage-link-target"><span>Galego</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EB%B0%94%EC%9D%B4%EC%98%A4%EC%8A%A4" title="바이오스 – Korean" lang="ko" hreflang="ko" data-title="바이오스" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-ha mw-list-item"><a href="https://ha.wikipedia.org/wiki/BIOS" title="BIOS – Hausa" lang="ha" hreflang="ha" data-title="BIOS" data-language-autonym="Hausa" data-language-local-name="Hausa" class="interlanguage-link-target"><span>Hausa</span></a></li><li class="interlanguage-link interwiki-hi mw-list-item"><a href="https://hi.wikipedia.org/wiki/%E0%A4%AC%E0%A4%BE%E0%A4%AF%E0%A5%8B%E0%A4%B8" title="बायोस – Hindi" lang="hi" hreflang="hi" data-title="बायोस" data-language-autonym="हिन्दी" data-language-local-name="Hindi" class="interlanguage-link-target"><span>हिन्दी</span></a></li><li class="interlanguage-link interwiki-hr mw-list-item"><a href="https://hr.wikipedia.org/wiki/BIOS" title="BIOS – Croatian" lang="hr" hreflang="hr" data-title="BIOS" data-language-autonym="Hrvatski" data-language-local-name="Croatian" class="interlanguage-link-target"><span>Hrvatski</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/BIOS" title="BIOS – Indonesian" lang="id" hreflang="id" data-title="BIOS" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-is mw-list-item"><a href="https://is.wikipedia.org/wiki/Grunnst%C3%BDringarkerfi" title="Grunnstýringarkerfi – Icelandic" lang="is" hreflang="is" data-title="Grunnstýringarkerfi" data-language-autonym="Íslenska" data-language-local-name="Icelandic" class="interlanguage-link-target"><span>Íslenska</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/BIOS" title="BIOS – Italian" lang="it" hreflang="it" data-title="BIOS" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/BIOS" title="BIOS – Hebrew" lang="he" hreflang="he" data-title="BIOS" data-language-autonym="עברית" data-language-local-name="Hebrew" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-pam mw-list-item"><a href="https://pam.wikipedia.org/wiki/Basic_Input_Output_System" title="Basic Input Output System – Pampanga" lang="pam" hreflang="pam" data-title="Basic Input Output System" data-language-autonym="Kapampangan" data-language-local-name="Pampanga" class="interlanguage-link-target"><span>Kapampangan</span></a></li><li class="interlanguage-link interwiki-ka mw-list-item"><a href="https://ka.wikipedia.org/wiki/BIOS" title="BIOS – Georgian" lang="ka" hreflang="ka" data-title="BIOS" data-language-autonym="ქართული" data-language-local-name="Georgian" class="interlanguage-link-target"><span>ქართული</span></a></li><li class="interlanguage-link interwiki-kk mw-list-item"><a href="https://kk.wikipedia.org/wiki/%D0%91%D0%B0%D0%B7%D0%B0%D0%BB%D1%8B%D2%9B_%D0%B5%D0%BD%D0%B3%D1%96%D0%B7%D1%83-%D1%88%D1%8B%D2%93%D0%B0%D1%80%D1%83_%D0%B6%D2%AF%D0%B9%D0%B5%D1%81%D1%96" title="Базалық енгізу-шығару жүйесі – Kazakh" lang="kk" hreflang="kk" data-title="Базалық енгізу-шығару жүйесі" data-language-autonym="Қазақша" data-language-local-name="Kazakh" class="interlanguage-link-target"><span>Қазақша</span></a></li><li class="interlanguage-link interwiki-ku mw-list-item"><a href="https://ku.wikipedia.org/wiki/BIOS" title="BIOS – Kurdish" lang="ku" hreflang="ku" data-title="BIOS" data-language-autonym="Kurdî" data-language-local-name="Kurdish" class="interlanguage-link-target"><span>Kurdî</span></a></li><li class="interlanguage-link interwiki-lv mw-list-item"><a href="https://lv.wikipedia.org/wiki/BIOS" title="BIOS – Latvian" lang="lv" hreflang="lv" data-title="BIOS" data-language-autonym="Latviešu" data-language-local-name="Latvian" class="interlanguage-link-target"><span>Latviešu</span></a></li><li class="interlanguage-link interwiki-lb mw-list-item"><a href="https://lb.wikipedia.org/wiki/BIOS" title="BIOS – Luxembourgish" lang="lb" hreflang="lb" data-title="BIOS" data-language-autonym="Lëtzebuergesch" data-language-local-name="Luxembourgish" class="interlanguage-link-target"><span>Lëtzebuergesch</span></a></li><li class="interlanguage-link interwiki-lt mw-list-item"><a href="https://lt.wikipedia.org/wiki/BIOS" title="BIOS – Lithuanian" lang="lt" hreflang="lt" data-title="BIOS" data-language-autonym="Lietuvių" data-language-local-name="Lithuanian" class="interlanguage-link-target"><span>Lietuvių</span></a></li><li class="interlanguage-link interwiki-lmo mw-list-item"><a href="https://lmo.wikipedia.org/wiki/BIOS" title="BIOS – Lombard" lang="lmo" hreflang="lmo" data-title="BIOS" data-language-autonym="Lombard" data-language-local-name="Lombard" class="interlanguage-link-target"><span>Lombard</span></a></li><li class="interlanguage-link interwiki-hu mw-list-item"><a href="https://hu.wikipedia.org/wiki/BIOS" title="BIOS – Hungarian" lang="hu" hreflang="hu" data-title="BIOS" data-language-autonym="Magyar" data-language-local-name="Hungarian" class="interlanguage-link-target"><span>Magyar</span></a></li><li class="interlanguage-link interwiki-ml mw-list-item"><a href="https://ml.wikipedia.org/wiki/%E0%B4%AC%E0%B4%AF%E0%B5%8B%E0%B4%B8%E0%B5%8D" title="ബയോസ് – Malayalam" lang="ml" hreflang="ml" data-title="ബയോസ്" data-language-autonym="മലയാളം" data-language-local-name="Malayalam" class="interlanguage-link-target"><span>മലയാളം</span></a></li><li class="interlanguage-link interwiki-ms mw-list-item"><a href="https://ms.wikipedia.org/wiki/BIOS" title="BIOS – Malay" lang="ms" hreflang="ms" data-title="BIOS" data-language-autonym="Bahasa Melayu" data-language-local-name="Malay" class="interlanguage-link-target"><span>Bahasa Melayu</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Basic_input/output_system" title="Basic input/output system – Dutch" lang="nl" hreflang="nl" data-title="Basic input/output system" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/Basic_Input/Output_System" title="Basic Input/Output System – Japanese" lang="ja" hreflang="ja" data-title="Basic Input/Output System" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/BIOS" title="BIOS – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="BIOS" data-language-autonym="Norsk bokmål" data-language-local-name="Norwegian Bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-nn mw-list-item"><a href="https://nn.wikipedia.org/wiki/BIOS" title="BIOS – Norwegian Nynorsk" lang="nn" hreflang="nn" data-title="BIOS" data-language-autonym="Norsk nynorsk" data-language-local-name="Norwegian Nynorsk" class="interlanguage-link-target"><span>Norsk nynorsk</span></a></li><li class="interlanguage-link interwiki-uz mw-list-item"><a href="https://uz.wikipedia.org/wiki/BIOS" title="BIOS – Uzbek" lang="uz" hreflang="uz" data-title="BIOS" data-language-autonym="Oʻzbekcha / ўзбекча" data-language-local-name="Uzbek" class="interlanguage-link-target"><span>Oʻzbekcha / ўзбекча</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/BIOS" title="BIOS – Polish" lang="pl" hreflang="pl" data-title="BIOS" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/BIOS" title="BIOS – Portuguese" lang="pt" hreflang="pt" data-title="BIOS" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ro mw-list-item"><a href="https://ro.wikipedia.org/wiki/BIOS" title="BIOS – Romanian" lang="ro" hreflang="ro" data-title="BIOS" data-language-autonym="Română" data-language-local-name="Romanian" class="interlanguage-link-target"><span>Română</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/BIOS" title="BIOS – Russian" lang="ru" hreflang="ru" data-title="BIOS" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-sq mw-list-item"><a href="https://sq.wikipedia.org/wiki/BIOS" title="BIOS – Albanian" lang="sq" hreflang="sq" data-title="BIOS" data-language-autonym="Shqip" data-language-local-name="Albanian" class="interlanguage-link-target"><span>Shqip</span></a></li><li class="interlanguage-link interwiki-simple mw-list-item"><a href="https://simple.wikipedia.org/wiki/BIOS" title="BIOS – Simple English" lang="en-simple" hreflang="en-simple" data-title="BIOS" data-language-autonym="Simple English" data-language-local-name="Simple English" class="interlanguage-link-target"><span>Simple English</span></a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/Basic_Input_Output_System" title="Basic Input Output System – Slovak" lang="sk" hreflang="sk" data-title="Basic Input Output System" data-language-autonym="Slovenčina" data-language-local-name="Slovak" class="interlanguage-link-target"><span>Slovenčina</span></a></li><li class="interlanguage-link interwiki-sl mw-list-item"><a href="https://sl.wikipedia.org/wiki/BIOS" title="BIOS – Slovenian" lang="sl" hreflang="sl" data-title="BIOS" data-language-autonym="Slovenščina" data-language-local-name="Slovenian" class="interlanguage-link-target"><span>Slovenščina</span></a></li><li class="interlanguage-link interwiki-ckb mw-list-item"><a href="https://ckb.wikipedia.org/wiki/%D8%A8%D8%A7%DB%8C%DB%86%D8%B3" title="بایۆس – Central Kurdish" lang="ckb" hreflang="ckb" data-title="بایۆس" data-language-autonym="کوردی" data-language-local-name="Central Kurdish" class="interlanguage-link-target"><span>کوردی</span></a></li><li class="interlanguage-link interwiki-sr mw-list-item"><a href="https://sr.wikipedia.org/wiki/BIOS" title="BIOS – Serbian" lang="sr" hreflang="sr" data-title="BIOS" data-language-autonym="Српски / srpski" data-language-local-name="Serbian" class="interlanguage-link-target"><span>Српски / srpski</span></a></li><li class="interlanguage-link interwiki-sh mw-list-item"><a href="https://sh.wikipedia.org/wiki/BIOS" title="BIOS – Serbo-Croatian" lang="sh" hreflang="sh" data-title="BIOS" data-language-autonym="Srpskohrvatski / српскохрватски" data-language-local-name="Serbo-Croatian" class="interlanguage-link-target"><span>Srpskohrvatski / српскохрватски</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/BIOS" title="BIOS – Finnish" lang="fi" hreflang="fi" data-title="BIOS" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/Basic_Input/Output_System" title="Basic Input/Output System – Swedish" lang="sv" hreflang="sv" data-title="Basic Input/Output System" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-tl mw-list-item"><a href="https://tl.wikipedia.org/wiki/BIOS" title="BIOS – Tagalog" lang="tl" hreflang="tl" data-title="BIOS" data-language-autonym="Tagalog" data-language-local-name="Tagalog" class="interlanguage-link-target"><span>Tagalog</span></a></li><li class="interlanguage-link interwiki-ta mw-list-item"><a href="https://ta.wikipedia.org/wiki/%E0%AE%AA%E0%AE%AF%E0%AE%BE%E0%AE%B8%E0%AF%8D" title="பயாஸ் – Tamil" lang="ta" hreflang="ta" data-title="பயாஸ்" data-language-autonym="தமிழ்" data-language-local-name="Tamil" class="interlanguage-link-target"><span>தமிழ்</span></a></li><li class="interlanguage-link interwiki-te mw-list-item"><a href="https://te.wikipedia.org/wiki/%E0%B0%AC%E0%B0%AF%E0%B1%8B%E0%B0%B8%E0%B1%8D" title="బయోస్ – Telugu" lang="te" hreflang="te" data-title="బయోస్" data-language-autonym="తెలుగు" data-language-local-name="Telugu" class="interlanguage-link-target"><span>తెలుగు</span></a></li><li class="interlanguage-link interwiki-th mw-list-item"><a href="https://th.wikipedia.org/wiki/%E0%B9%84%E0%B8%9A%E0%B8%AD%E0%B8%AD%E0%B8%AA" title="ไบออส – Thai" lang="th" hreflang="th" data-title="ไบออส" data-language-autonym="ไทย" data-language-local-name="Thai" class="interlanguage-link-target"><span>ไทย</span></a></li><li class="interlanguage-link interwiki-tg mw-list-item"><a href="https://tg.wikipedia.org/wiki/BIOS" title="BIOS – Tajik" lang="tg" hreflang="tg" data-title="BIOS" data-language-autonym="Тоҷикӣ" data-language-local-name="Tajik" class="interlanguage-link-target"><span>Тоҷикӣ</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/BIOS" title="BIOS – Turkish" lang="tr" hreflang="tr" data-title="BIOS" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/BIOS" title="BIOS – Ukrainian" lang="uk" hreflang="uk" data-title="BIOS" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-vi mw-list-item"><a href="https://vi.wikipedia.org/wiki/BIOS" title="BIOS – Vietnamese" lang="vi" hreflang="vi" data-title="BIOS" data-language-autonym="Tiếng Việt" data-language-local-name="Vietnamese" class="interlanguage-link-target"><span>Tiếng Việt</span></a></li><li class="interlanguage-link interwiki-wuu mw-list-item"><a href="https://wuu.wikipedia.org/wiki/BIOS" title="BIOS – Wu" lang="wuu" hreflang="wuu" data-title="BIOS" data-language-autonym="吴语" data-language-local-name="Wu" class="interlanguage-link-target"><span>吴语</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/BIOS" title="BIOS – Chinese" lang="zh" hreflang="zh" data-title="BIOS" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target"><span>中文</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span class="wb-langlinks-edit wb-langlinks-link"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q226264#sitelinks-wikipedia" title="Edit interlanguage links" class="wbc-editpage">Edit links</a></span></div> </div> </div> </div> </header> <div class="vector-page-toolbar"> <div class="vector-page-toolbar-container"> <div id="left-navigation"> <nav aria-label="Namespaces"> <div id="p-associated-pages" class="vector-menu vector-menu-tabs mw-portlet mw-portlet-associated-pages" > <div class="vector-menu-content"> <ul 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class="vector-body" aria-labelledby="firstHeading" data-mw-ve-target-container> <div class="vector-body-before-content"> <div class="mw-indicators"> </div> <div id="siteSub" class="noprint">From Wikipedia, the free encyclopedia</div> </div> <div id="contentSub"><div id="mw-content-subtitle"></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Firmware for hardware initialization and OS runtime services</div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">This article is about the BIOS as found in IBM PC/AT and compatibles.. For the modern replacement that is often still called BIOS, see <a href="/wiki/UEFI" title="UEFI">UEFI</a>. For the general concept, see <a href="/wiki/Firmware" title="Firmware">Firmware</a>. For other uses, see <a href="/wiki/Bios_(disambiguation)" class="mw-redirect mw-disambig" title="Bios (disambiguation)">Bios (disambiguation)</a>.</div> <p class="mw-empty-elt"> </p> <style data-mw-deduplicate="TemplateStyles:r1257001546">.mw-parser-output .infobox-subbox{padding:0;border:none;margin:-3px;width:auto;min-width:100%;font-size:100%;clear:none;float:none;background-color:transparent}.mw-parser-output .infobox-3cols-child{margin:auto}.mw-parser-output .infobox .navbar{font-size:100%}@media screen{html.skin-theme-clientpref-night .mw-parser-output .infobox-full-data:not(.notheme)>div:not(.notheme)[style]{background:#1f1f23!important;color:#f8f9fa}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .infobox-full-data:not(.notheme) div:not(.notheme){background:#1f1f23!important;color:#f8f9fa}}@media(min-width:640px){body.skin--responsive .mw-parser-output .infobox-table{display:table!important}body.skin--responsive .mw-parser-output .infobox-table>caption{display:table-caption!important}body.skin--responsive .mw-parser-output .infobox-table>tbody{display:table-row-group}body.skin--responsive .mw-parser-output .infobox-table tr{display:table-row!important}body.skin--responsive .mw-parser-output .infobox-table th,body.skin--responsive .mw-parser-output .infobox-table td{padding-left:inherit;padding-right:inherit}}</style><table class="infobox hproduct"><tbody><tr><td colspan="2" class="infobox-image"><span class="mw-default-size" typeof="mw:File/Frameless"><a href="/wiki/File:Pair_of_BIOS_chips.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/1/15/Pair_of_BIOS_chips.jpg/220px-Pair_of_BIOS_chips.jpg" decoding="async" width="220" height="195" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/15/Pair_of_BIOS_chips.jpg/330px-Pair_of_BIOS_chips.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/15/Pair_of_BIOS_chips.jpg/440px-Pair_of_BIOS_chips.jpg 2x" data-file-width="4511" data-file-height="4000" /></a></span><div class="infobox-caption">A pair of <a href="/wiki/Advanced_Micro_Devices" class="mw-redirect" title="Advanced Micro Devices">AMD</a> BIOS chips for a <a href="/wiki/Dell" title="Dell">Dell</a> 310 computer from the 1980s. The bottom one shows the distinct window of an <a href="/wiki/EPROM" title="EPROM">EPROM</a> chip.</div></td></tr><tr><th scope="row" class="infobox-label">Year started</th><td class="infobox-data">1981<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>a<span class="cite-bracket">]</span></a></sup></td></tr><tr><th scope="row" class="infobox-label">Organization</th><td class="infobox-data">Originally <a href="/wiki/IBM" title="IBM">IBM</a> as proprietary software, later industry wide as a <a href="/wiki/De_facto" title="De facto">de facto</a> standard. In 1996, the <i>BIOS Boot Specification</i> was written by <a href="/wiki/Compaq" title="Compaq">Compaq</a>, <a href="/wiki/Phoenix_Technologies" title="Phoenix Technologies">Phoenix Technologies</a> and <a href="/wiki/Intel" title="Intel">Intel</a>.</td></tr><tr><th scope="row" class="infobox-label">Successor</th><td class="infobox-data"><a href="/wiki/UEFI" title="UEFI">UEFI</a></td></tr></tbody></table> <p>In <a href="/wiki/Computing" title="Computing">computing</a>, <b>BIOS</b> (<span class="rt-commentedText nowrap"><span class="IPA nopopups noexcerpt" lang="en-fonipa"><a href="/wiki/Help:IPA/English" title="Help:IPA/English">/<span style="border-bottom:1px dotted"><span title="/ˈ/: primary stress follows">ˈ</span><span title="'b' in 'buy'">b</span><span title="/aɪ/: 'i' in 'tide'">aɪ</span><span title="/ɒ/: 'o' in 'body'">ɒ</span><span title="'s' in 'sigh'">s</span></span>,<span class="wrap"> </span>-<span style="border-bottom:1px dotted"><span title="/oʊ/: 'o' in 'code'">oʊ</span><span title="'s' in 'sigh'">s</span></span>/</a></span></span>, <a href="/wiki/Help:Pronunciation_respelling_key" title="Help:Pronunciation respelling key"><i title="English pronunciation respelling"><span style="font-size:90%">BY</span>-oss, -⁠ohss</i></a>; <b>Basic Input/Output System</b>, also known as the <b>System BIOS</b>, <b>ROM BIOS</b>, <b>BIOS ROM</b> or <b>PC BIOS</b>) is <a href="/wiki/Firmware" title="Firmware">firmware</a> used to provide runtime services for <a href="/wiki/Operating_system" title="Operating system">operating systems</a> and <a href="/wiki/Computer_program" title="Computer program">programs</a> and to perform <a href="/wiki/Computer_hardware" title="Computer hardware">hardware</a> initialization during the <a href="/wiki/Booting" title="Booting">booting</a> process (power-on startup).<sup id="cite_ref-pcguidedefinition_2-0" class="reference"><a href="#cite_note-pcguidedefinition-2"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> The firmware comes pre-installed on the computer's <a href="/wiki/Motherboard" title="Motherboard">motherboard</a>. </p><p>The name originates from the Basic Input/Output System used in the <a href="/wiki/CP/M" title="CP/M">CP/M</a> operating system in 1975.<sup id="cite_ref-Kildall_1975_BDOS_3-0" class="reference"><a href="#cite_note-Kildall_1975_BDOS-3"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Kildall_1980_CPM_4-0" class="reference"><a href="#cite_note-Kildall_1980_CPM-4"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> The BIOS firmware was originally <a href="/wiki/Proprietary_software" title="Proprietary software">proprietary</a> to the <a href="/wiki/IBM_PC" class="mw-redirect" title="IBM PC">IBM PC</a>; it was <a href="/wiki/Reverse_engineer" class="mw-redirect" title="Reverse engineer">reverse engineered</a> by some companies (such as <a href="/wiki/Phoenix_Technologies" title="Phoenix Technologies">Phoenix Technologies</a>) looking to create compatible systems. The <a href="/wiki/Interface_(computing)" title="Interface (computing)">interface</a> of that original system serves as a <a href="/wiki/De_facto_standard" title="De facto standard"><i>de facto</i> standard</a>. </p><p>The BIOS in older PCs initializes and tests the system hardware components (<a href="/wiki/Power-on_self-test" title="Power-on self-test">power-on self-test</a> or POST for short), and loads a <a href="/wiki/Boot_loader" class="mw-redirect" title="Boot loader">boot loader</a> from a mass storage device which then initializes a <a href="/wiki/Kernel_(operating_system)" title="Kernel (operating system)">kernel</a>. In the era of <a href="/wiki/DOS" title="DOS">DOS</a>, the BIOS provided <a href="/wiki/BIOS_interrupt_call" title="BIOS interrupt call">BIOS interrupt calls</a> for the keyboard, display, storage, and other <a href="/wiki/Input/output" title="Input/output">input/output</a> (I/O) devices that standardized an interface to application programs and the operating system. More recent operating systems do not use the BIOS interrupt calls after startup.<sup id="cite_ref-Booting_·_Linux_Inside_5-0" class="reference"><a href="#cite_note-Booting_·_Linux_Inside-5"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p><p>Most BIOS implementations are specifically designed to work with a particular computer or <a href="/wiki/Motherboard" title="Motherboard">motherboard</a> model, by interfacing with various devices especially system <a href="/wiki/Chipset" title="Chipset">chipset</a>. Originally, BIOS firmware was stored in a <a href="/wiki/Read-only_memory" title="Read-only memory">ROM</a> chip on the PC motherboard. In later computer systems, the BIOS contents are stored on <a href="/wiki/Flash_memory" title="Flash memory">flash memory</a> so it can be rewritten without removing the chip from the motherboard. This allows easy, end-user updates to the BIOS firmware so new features can be added or bugs can be fixed, but it also creates a possibility for the computer to become infected with BIOS <a href="/wiki/Rootkit" title="Rootkit">rootkits</a>. Furthermore, a BIOS upgrade that fails could <a href="/wiki/Brick_(electronics)" title="Brick (electronics)">brick</a> the motherboard. </p><p><a href="/wiki/Unified_Extensible_Firmware_Interface" class="mw-redirect" title="Unified Extensible Firmware Interface">Unified Extensible Firmware Interface</a> (UEFI) is a successor to the legacy PC BIOS, aiming to address its technical limitations.<sup id="cite_ref-Bradley_6-0" class="reference"><a href="#cite_note-Bradley-6"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> UEFI firmware may include legacy BIOS compatibility to maintain compatibility with operating systems and option cards that do not support UEFI native operation.<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> Since 2020, all PCs for Intel platforms no longer support Legacy BIOS.<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> The last version of <a href="/wiki/Microsoft_Windows" title="Microsoft Windows">Microsoft Windows</a> to officially support running on PCs which use legacy BIOS firmware is <a href="/wiki/Windows_10" title="Windows 10">Windows 10</a> as <a href="/wiki/Windows_11" title="Windows 11">Windows 11</a> requires a UEFI-compliant system (except for IoT Enterprise editions of Windows 11 since version 24H2<sup id="cite_ref-11_IoT_req_11-0" class="reference"><a href="#cite_note-11_IoT_req-11"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup>). </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="History">History</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=1" title="Edit section: History"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1023981488">@media all and (max-width:720px){.mw-parser-output .rquote{width:auto!important;float:none!important}}</style><style data-mw-deduplicate="TemplateStyles:r1244412712">.mw-parser-output .templatequote{overflow:hidden;margin:1em 0;padding:0 32px}.mw-parser-output .templatequotecite{line-height:1.5em;text-align:left;margin-top:0}@media(min-width:500px){.mw-parser-output .templatequotecite{padding-left:1.6em}}</style><blockquote class="templatequote rquote" style="float: right; width: 33%;"><pre>/* C P / M B A S I C I / O S Y S T E M (B I O S) COPYRIGHT (C) GARY A. KILDALL JUNE, 1975 */ […] /* B A S I C D I S K O P E R A T I N G S Y S T E M (B D O S) COPYRIGHT (C) GARY A. KILDALL JUNE, 1975 */</pre><div class="templatequotecite">— <cite>An excerpt from the BDOS.PLM file header in the <a href="/wiki/PL/M" title="PL/M">PL/M</a> source code of CP/M 1.1 or 1.2 for <a href="/wiki/Lawrence_Livermore_Laboratories" class="mw-redirect" title="Lawrence Livermore Laboratories">Lawrence Livermore Laboratories</a> (LLL)<sup id="cite_ref-Kildall_1975_BDOS_3-1" class="reference"><a href="#cite_note-Kildall_1975_BDOS-3"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup></cite></div></blockquote> <p>The term BIOS (Basic Input/Output System) was created by <a href="/wiki/Gary_Kildall" title="Gary Kildall">Gary Kildall</a><sup id="cite_ref-Swaine_1997_Entrepreneurship_12-0" class="reference"><a href="#cite_note-Swaine_1997_Entrepreneurship-12"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-IEEE_2014_BIOS_13-0" class="reference"><a href="#cite_note-IEEE_2014_BIOS-13"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> and first appeared in the <a href="/wiki/CP/M" title="CP/M">CP/M</a> operating system in 1975,<sup id="cite_ref-Kildall_1975_BDOS_3-2" class="reference"><a href="#cite_note-Kildall_1975_BDOS-3"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Kildall_1980_CPM_4-1" class="reference"><a href="#cite_note-Kildall_1980_CPM-4"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-IEEE_2014_BIOS_13-1" class="reference"><a href="#cite_note-IEEE_2014_BIOS-13"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Shustek_2016_14-0" class="reference"><a href="#cite_note-Shustek_2016-14"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Fischer_2001_Ewing_15-0" class="reference"><a href="#cite_note-Fischer_2001_Ewing-15"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Fraley_2007_Killian_16-0" class="reference"><a href="#cite_note-Fraley_2007_Killian-16"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> describing the machine-specific part of CP/M loaded during boot time that interfaces directly with the <a href="/wiki/Computer_hardware" title="Computer hardware">hardware</a>.<sup id="cite_ref-Kildall_1980_CPM_4-2" class="reference"><a href="#cite_note-Kildall_1980_CPM-4"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> (A CP/M machine usually has only a simple <a href="/wiki/Boot_loader" class="mw-redirect" title="Boot loader">boot loader</a> in its ROM.) </p><p>Versions of <a href="/wiki/MS-DOS" title="MS-DOS">MS-DOS</a>, <a href="/wiki/PC_DOS" class="mw-redirect" title="PC DOS">PC DOS</a> or <a href="/wiki/DR-DOS" title="DR-DOS">DR-DOS</a> contain a file called variously "<a href="/wiki/IO.SYS" title="IO.SYS">IO.SYS</a>", "<a href="/wiki/IBMBIO.COM" title="IBMBIO.COM">IBMBIO.COM</a>", "IBMBIO.SYS", or "DRBIOS.SYS"; this file is known as the "DOS BIOS" (also known as the "DOS I/O System") and contains the lower-level hardware-specific part of the operating system. Together with the underlying hardware-specific but operating system-independent "System BIOS", which resides in <a href="/wiki/Read-only_memory" title="Read-only memory">ROM</a>, it represents the analogue to the "<a href="/wiki/CP/M_BIOS" class="mw-redirect" title="CP/M BIOS">CP/M BIOS</a>". </p><p>The BIOS originally <a href="/wiki/Proprietary_software" title="Proprietary software">proprietary</a> to the <a href="/wiki/IBM_Personal_Computer" title="IBM Personal Computer">IBM PC</a> has been <a href="/wiki/Reverse_engineer" class="mw-redirect" title="Reverse engineer">reverse engineered</a> by some companies (such as <a href="/wiki/Phoenix_Technologies" title="Phoenix Technologies">Phoenix Technologies</a>) looking to create compatible systems. </p><p>With the introduction of PS/2 machines, IBM divided the System BIOS into real- and protected-mode portions. The real-mode portion was meant to provide backward compatibility with existing operating systems such as DOS, and therefore was named "CBIOS" (for "Compatibility BIOS"), whereas the "ABIOS" (for "Advanced BIOS") provided new interfaces specifically suited for multitasking operating systems such as <a href="/wiki/OS/2" title="OS/2">OS/2</a>.<sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="User_interface"><span class="anchor" id="BCU"></span>User interface</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=2" title="Edit section: User interface"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The BIOS of the original <a href="/wiki/IBM_Personal_Computer" title="IBM Personal Computer">IBM PC</a> and <a href="/wiki/IBM_Personal_Computer_XT" title="IBM Personal Computer XT">XT</a> had no interactive user interface. Error codes or messages were displayed on the screen, or coded series of sounds were generated to signal errors when the <a href="/wiki/Power-on_self-test" title="Power-on self-test">power-on self-test</a> (POST) had not proceeded to the point of successfully initializing a video display adapter. Options on the IBM PC and XT were set by switches and jumpers on the main board and on <a href="/wiki/Expansion_card" title="Expansion card">expansion cards</a>. Starting around the mid-1990s, it became typical for the BIOS ROM to include a <i>"BIOS configuration utility"</i> (BCU<sup id="cite_ref-18" class="reference"><a href="#cite_note-18"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup>) or "BIOS setup utility", accessed at system power-up by a particular key sequence. This program allowed the user to set system configuration options, of the type formerly set using <a href="/wiki/DIP_switch" title="DIP switch">DIP switches</a>, through an interactive menu system controlled through the keyboard. In the interim period, IBM-compatible PCs‍—‌including the <a href="/wiki/IBM_Personal_Computer/AT" class="mw-redirect" title="IBM Personal Computer/AT">IBM AT</a>‍—‌held configuration settings in battery-backed RAM and used a bootable configuration program on floppy disk, not in the ROM, to set the configuration options contained in this memory. The floppy disk was supplied with the computer, and if it was lost the system settings could not be changed. The same applied in general to computers with an <a href="/wiki/Extended_Industry_Standard_Architecture" title="Extended Industry Standard Architecture">EISA</a> bus, for which the configuration program was called an EISA Configuration Utility (ECU). </p><p>A modern <a href="/wiki/Wintel" title="Wintel">Wintel</a>-compatible computer provides a setup routine essentially unchanged in nature from the ROM-resident BIOS setup utilities of the late 1990s; the user can configure hardware options using the keyboard and video display. The modern Wintel machine may store the BIOS configuration settings in flash ROM, perhaps the same flash ROM that holds the BIOS itself. </p> <div class="mw-heading mw-heading2"><h2 id="Extensions_(option_ROMs)"><span id="Extensions_.28option_ROMs.29"></span>Extensions (option ROMs)</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=3" title="Edit section: Extensions (option ROMs)"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Option_ROM" title="Option ROM">Option ROM</a></div> <p>Peripheral cards such as hard disk drive <a href="/wiki/Host_bus_adapter" class="mw-redirect" title="Host bus adapter">host bus adapters</a> and <a href="/wiki/Video_card" class="mw-redirect" title="Video card">video cards</a> have their own firmware, and BIOS extension <a href="/wiki/Option_ROM" title="Option ROM">option ROM</a> code may be a part of the expansion card firmware; that code provides additional capabilities in the BIOS. Code in option ROMs runs before the BIOS boots the operating system from <a href="/wiki/Mass_storage" title="Mass storage">mass storage</a>. These ROMs typically test and initialize hardware, add new BIOS services, or replace existing BIOS services with their own services. For example, a <a href="/wiki/SCSI_controller" class="mw-redirect" title="SCSI controller">SCSI controller</a> usually has a BIOS extension ROM that adds support for hard drives connected through that controller. An extension ROM could in principle contain operating system, or it could implement an entirely different boot process such as <a href="/wiki/Network_booting" title="Network booting">network booting</a>. Operation of an IBM-compatible computer system can be completely changed by removing or inserting an adapter card (or a ROM chip) that contains a BIOS extension ROM. </p><p>The motherboard BIOS typically contains code for initializing and bootstrapping integrated display and integrated storage. The initialization process can involve the execution of code related to the device being initialized, for locating the device, verifying the type of device, then establishing base registers, setting <a href="/wiki/Pointer_(computer_programming)" title="Pointer (computer programming)">pointers</a>, establishing interrupt vector tables,<sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> selecting paging modes which are ways for organizing available <a href="/wiki/Processor_register" title="Processor register">registers</a> in devices, setting default values for accessing software routines related to <a href="/wiki/Interrupt#Hardware_interrupts" title="Interrupt">interrupts</a>,<sup id="cite_ref-20" class="reference"><a href="#cite_note-20"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup> and setting the device's configuration using default values.<sup id="cite_ref-21" class="reference"><a href="#cite_note-21"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup> In addition, plug-in adapter cards such as <a href="/wiki/SCSI" title="SCSI">SCSI</a>, <a href="/wiki/RAID" title="RAID">RAID</a>, <a href="/wiki/Network_interface_card" class="mw-redirect" title="Network interface card">network interface cards</a>, and <a href="/wiki/Video_card" class="mw-redirect" title="Video card">video cards</a> often include their own BIOS (e.g. <a href="/wiki/Video_BIOS" title="Video BIOS">Video BIOS</a>), complementing or replacing the system BIOS code for the given component. Even devices built into the motherboard can behave in this way; their option ROMs can be a part of the motherboard BIOS. </p><p>An add-in card requires an option ROM if the card is not supported by the motherboard BIOS and the card needs to be initialized or made accessible through BIOS services before the operating system can be loaded (usually this means it is required in the boot process). An additional advantage of ROM on some early PC systems (notably including the IBM PCjr) was that ROM was faster than main system RAM. (On modern systems, the case is very much the reverse of this, and BIOS ROM code is usually copied ("shadowed") into RAM so it will run faster.) </p> <div class="mw-heading mw-heading3"><h3 id="Physical_placement">Physical placement</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=4" title="Edit section: Physical placement"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Dell_310_BIOS_chips.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/0/07/Dell_310_BIOS_chips.jpg/220px-Dell_310_BIOS_chips.jpg" decoding="async" width="220" height="147" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/07/Dell_310_BIOS_chips.jpg/330px-Dell_310_BIOS_chips.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/0/07/Dell_310_BIOS_chips.jpg/440px-Dell_310_BIOS_chips.jpg 2x" data-file-width="6016" data-file-height="4016" /></a><figcaption>BIOS chips in a Dell 310 that were updated by replacing the chips</figcaption></figure> <p>Option ROMs normally reside on adapter cards. However, the original PC, and perhaps also the PC XT, have a spare ROM socket on the motherboard (the "system board" in IBM's terms) into which an option ROM can be inserted, and the four ROMs that contain the BASIC interpreter can also be removed and replaced with custom ROMs which can be option ROMs. The <a href="/wiki/IBM_PCjr" title="IBM PCjr">IBM PCjr</a> is unique among PCs in having two ROM cartridge slots on the front. Cartridges in these slots map into the same region of the upper memory area used for option ROMs, and the cartridges can contain option ROM modules that the BIOS would recognize. The cartridges can also contain other types of ROM modules, such as BASIC programs, that are handled differently. One PCjr cartridge can contain several ROM modules of different types, possibly stored together in one ROM chip. </p> <div class="mw-heading mw-heading2"><h2 id="Operation">Operation</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=5" title="Edit section: Operation"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading3"><h3 id="System_startup">System startup</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=6" title="Edit section: System startup"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The <a href="/wiki/8086" class="mw-redirect" title="8086">8086</a> and <a href="/wiki/8088" class="mw-redirect" title="8088">8088</a> start at physical address FFFF0h.<sup id="cite_ref-22" class="reference"><a href="#cite_note-22"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup> The <a href="/wiki/80286" class="mw-redirect" title="80286">80286</a> starts at physical address FFFFF0h.<sup id="cite_ref-23" class="reference"><a href="#cite_note-23"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> The <a href="/wiki/80386" class="mw-redirect" title="80386">80386</a> and later x86 processors start at physical address FFFFFFF0h.<sup id="cite_ref-24" class="reference"><a href="#cite_note-24"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-25" class="reference"><a href="#cite_note-25"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-26" class="reference"><a href="#cite_note-26"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> When the system is initialized, the first instruction of the BIOS appears at that address. </p><p>If the system has just been powered up or the reset button was pressed ("<a href="/wiki/Cold_boot" class="mw-redirect" title="Cold boot">cold boot</a>"), the full <a href="/wiki/Power-on_self-test" title="Power-on self-test">power-on self-test</a> (POST) is run. If Ctrl+Alt+Delete was pressed ("<a href="/wiki/Reboot" title="Reboot">warm boot</a>"), a special flag value stored in <a href="/wiki/Nonvolatile_BIOS_memory" title="Nonvolatile BIOS memory">nonvolatile BIOS memory</a> ("<a href="/wiki/CMOS" title="CMOS">CMOS</a>") tested by the BIOS allows bypass of the lengthy POST and memory detection. </p><p>The POST identifies, tests and initializes system devices such as the <a href="/wiki/Central_processing_unit" title="Central processing unit">CPU</a>, <a href="/wiki/Chipset" title="Chipset">chipset</a>, <a href="/wiki/Random-access_memory" title="Random-access memory">RAM</a>, <a href="/wiki/Motherboard" title="Motherboard">motherboard</a>, <a href="/wiki/Video_card" class="mw-redirect" title="Video card">video card</a>, <a href="/wiki/Computer_keyboard" title="Computer keyboard">keyboard</a>, <a href="/wiki/Computer_mouse" title="Computer mouse">mouse</a>, <a href="/wiki/Hard_disk_drive" title="Hard disk drive">hard disk drive</a>, <a href="/wiki/Optical_disc_drive" title="Optical disc drive">optical disc drive</a> and other <a href="/wiki/Computer_hardware" title="Computer hardware">hardware</a>, including <a href="/wiki/Integrated_peripheral" class="mw-redirect" title="Integrated peripheral">integrated peripherals</a>. </p><p>Early IBM PCs had a routine in the POST that would download a program into RAM through the keyboard port and run it.<sup id="cite_ref-technical-ref-5-27_27-0" class="reference"><a href="#cite_note-technical-ref-5-27-27"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-28" class="reference"><a href="#cite_note-28"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup> This feature was intended for factory test or diagnostic purposes. </p><p>After the motherboard BIOS completes its POST, most BIOS versions search for option ROM modules, also called BIOS extension ROMs, and execute them. The motherboard BIOS scans for extension ROMs in a portion of the "<a href="/wiki/Upper_memory_area" title="Upper memory area">upper memory area</a>" (the part of the x86 real-mode address space at and above address 0xA0000) and runs each ROM found, in order. To discover memory-mapped option ROMs, a BIOS implementation scans the real-mode address space from <code>0x0C0000</code> to <code>0x0F0000</code> on 2 <a href="/wiki/Kilobyte" title="Kilobyte">KB</a> (2,048 bytes) boundaries, looking for a two-byte ROM <i>signature</i>: 0x55 followed by 0xAA. In a valid expansion ROM, this signature is followed by a single byte indicating the number of 512-byte blocks the expansion ROM occupies in real memory, and the next byte is the option ROM's <a href="/wiki/Entry_point" title="Entry point">entry point</a> (also known as its "entry offset"). If the ROM has a valid checksum, the BIOS transfers control to the entry address, which in a normal BIOS extension ROM should be the beginning of the extension's initialization routine. </p><p>At this point, the extension ROM code takes over, typically testing and initializing the hardware it controls and registering <a href="/wiki/Interrupt_vector" class="mw-redirect" title="Interrupt vector">interrupt vectors</a> for use by post-boot applications. It may use BIOS services (including those provided by previously initialized option ROMs) to provide a user configuration interface, to display diagnostic information, or to do anything else that it requires. </p><p>An option ROM should normally return to the BIOS after completing its initialization process. Once (and if) an option ROM returns, the BIOS continues searching for more option ROMs, calling each as it is found, until the entire option ROM area in the memory space has been scanned. It is possible that an option ROM will not return to BIOS, pre-empting the BIOS's boot sequence altogether. </p> <div class="mw-heading mw-heading3"><h3 id="Boot_process">Boot process</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=7" title="Edit section: Boot process"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-halign-none" typeof="mw:File/Thumb"><a href="/wiki/File:Legacy_BIOS_boot_process_fixed.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/2/20/Legacy_BIOS_boot_process_fixed.png/493px-Legacy_BIOS_boot_process_fixed.png" decoding="async" width="493" height="117" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/20/Legacy_BIOS_boot_process_fixed.png/740px-Legacy_BIOS_boot_process_fixed.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/20/Legacy_BIOS_boot_process_fixed.png/986px-Legacy_BIOS_boot_process_fixed.png 2x" data-file-width="6367" data-file-height="1508" /></a><figcaption>Boot process</figcaption></figure> <p>After the POST completes and, in a BIOS that supports option ROMs, after the option ROM scan is completed and all detected <a href="/wiki/Read-only_memory" title="Read-only memory">ROM</a> modules with valid <a href="/wiki/Checksum" title="Checksum">checksums</a> have been called, the BIOS calls <a href="/wiki/BIOS_interrupt_call#Interrupt_table" title="BIOS interrupt call">interrupt 19h</a> to start boot processing. Post-boot, programs loaded can also call interrupt 19h to reboot the system, but they must be careful to disable interrupts and other asynchronous hardware processes that may interfere with the BIOS rebooting process, or else the system may hang or crash while it is rebooting. </p><p>When interrupt 19h is called, the BIOS attempts to locate <a href="/wiki/Boot_loader" class="mw-redirect" title="Boot loader">boot loader</a> software on a "boot device", such as a <a href="/wiki/Hard_disk" class="mw-redirect" title="Hard disk">hard disk</a>, a <a href="/wiki/Floppy_disk" title="Floppy disk">floppy disk</a>, <a href="/wiki/CD" class="mw-redirect" title="CD">CD</a>, or <a href="/wiki/DVD" title="DVD">DVD</a>. It loads and executes the first boot <a href="/wiki/Software" title="Software">software</a> it finds, giving it control of the PC.<sup id="cite_ref-hsw1_29-0" class="reference"><a href="#cite_note-hsw1-29"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup> </p><p>The BIOS uses the boot devices set in <a href="/wiki/Nonvolatile_BIOS_memory" title="Nonvolatile BIOS memory">Nonvolatile BIOS memory</a> (<a href="/wiki/CMOS" title="CMOS">CMOS</a>), or, in the earliest PCs, <a href="/wiki/DIP_switch" title="DIP switch">DIP switches</a>. The BIOS checks each device in order to see if it is bootable by attempting to load the first sector (<a href="/wiki/Boot_sector" title="Boot sector">boot sector</a>). If the sector cannot be read, the BIOS proceeds to the next device. If the sector is read successfully, some BIOSes will also check for the boot sector signature 0x55 0xAA in the last two bytes of the sector (which is 512 bytes long), before accepting a boot sector and considering the device bootable.<sup id="cite_ref-30" class="reference"><a href="#cite_note-30"><span class="cite-bracket">[</span>b<span class="cite-bracket">]</span></a></sup> </p><p>When a bootable device is found, the BIOS transfers control to the loaded sector. The BIOS does not interpret the contents of the boot sector other than to possibly check for the boot sector signature in the last two bytes. Interpretation of data structures like partition tables and BIOS Parameter Blocks is done by the boot program in the boot sector itself or by other programs loaded through the boot process. </p><p>A non-disk device such as a <a href="/wiki/Network_adapter" class="mw-redirect" title="Network adapter">network adapter</a> attempts booting by a procedure that is defined by its <a href="/wiki/Option_ROM" title="Option ROM">option ROM</a> or the equivalent integrated into the motherboard BIOS ROM. As such, option ROMs may also influence or supplant the boot process defined by the motherboard BIOS ROM. </p><p>With the <a href="/wiki/El_Torito_(CD-ROM_standard)" class="mw-redirect" title="El Torito (CD-ROM standard)">El Torito optical media boot standard</a>, the optical drive actually emulates a 3.5" high-density floppy disk to the BIOS for boot purposes. Reading the "first sector" of a CD-ROM or DVD-ROM is not a simply defined operation like it is on a floppy disk or a hard disk. Furthermore, the complexity of the medium makes it difficult to write a useful boot program in one sector. The bootable virtual floppy disk can contain software that provides access to the optical medium in its native format. </p><p>If an expansion ROM wishes to change the way the system boots (such as from a network device or a SCSI adapter) in a cooperative way, it can use the <i>BIOS Boot Specification</i> (BBS) <a href="/wiki/API" title="API">API</a> to register its ability to do so. Once the expansion ROMs have registered using the BBS APIs, the user can select among the available boot options from within the BIOS's user interface. This is why most BBS compliant PC BIOS implementations will not allow the user to enter the BIOS's user interface until the expansion ROMs have finished executing and registering themselves with the BBS API.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (October 2008)">citation needed</span></a></i>]</sup> </p><p>Also, if an expansion ROM wishes to change the way the system boots unilaterally, it can simply hook interrupt 19h or other interrupts normally called from interrupt 19h, such as interrupt 13h, the BIOS disk service, to intercept the BIOS boot process. Then it can replace the BIOS boot process with one of its own, or it can merely modify the boot sequence by inserting its own boot actions into it, by preventing the BIOS from detecting certain devices as bootable, or both. Before the BIOS Boot Specification was promulgated, this was the only way for expansion ROMs to implement boot capability for devices not supported for booting by the native BIOS of the motherboard.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (October 2014)">citation needed</span></a></i>]</sup> </p> <div class="mw-heading mw-heading4"><h4 id="Boot_priority">Boot priority</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=8" title="Edit section: Boot priority"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The user can select the boot priority implemented by the BIOS. For example, most computers have a hard disk that is bootable, but sometimes there is a removable-media drive that has higher boot priority, so the user can cause a removable disk to be booted. </p><p>In most modern BIOSes, the boot priority order can be configured by the user. In older BIOSes, limited boot priority options are selectable; in the earliest BIOSes, a fixed priority scheme was implemented, with floppy disk drives first, fixed disks (i.e., hard disks) second, and typically no other boot devices supported, subject to modification of these rules by installed option ROMs. The BIOS in an early PC also usually would only boot from the first floppy disk drive or the first hard disk drive, even if there were two drives installed. </p> <div class="mw-heading mw-heading4"><h4 id="Boot_failure">Boot failure</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=9" title="Edit section: Boot failure"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>On the original <a href="/wiki/IBM_PC" class="mw-redirect" title="IBM PC">IBM PC</a> and XT, if no bootable disk was found, the BIOS would try to start <a href="/wiki/IBM_BASIC" title="IBM BASIC">ROM BASIC</a> with the interrupt call to <a href="/wiki/BIOS_interrupt_call#INT_18h:_execute_BASIC" title="BIOS interrupt call">interrupt 18h</a>. Since few programs used BASIC in ROM, clone PC makers left it out; then a computer that failed to boot from a disk would display "No ROM BASIC" and halt (in response to interrupt 18h). </p><p>Later computers would display a message like "No bootable disk found"; some would prompt for a disk to be inserted and a key to be pressed to retry the boot process. A modern BIOS may display nothing or may automatically enter the BIOS configuration utility when the boot process fails. </p> <div class="mw-heading mw-heading3"><h3 id="Boot_environment">Boot environment</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=10" title="Edit section: Boot environment"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The environment for the boot program is very simple: the CPU is in real mode and the general-purpose and segment registers are undefined, except SS, SP, CS, and DL. CS:IP always points to physical address <code>0x07C00</code>. What values CS and IP actually have is not well defined. Some BIOSes use a CS:IP of <code>0x0000:0x7C00</code> while others may use <code>0x07C0:0x0000</code>.<sup id="cite_ref-31" class="reference"><a href="#cite_note-31"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> Because boot programs are always loaded at this fixed address, there is no need for a boot program to be relocatable. DL may contain the drive number, as used with <a href="/wiki/INT_13H" title="INT 13H">interrupt 13h</a>, of the boot device. SS:SP points to a valid stack that is presumably large enough to support hardware interrupts, but otherwise SS and SP are undefined. (A stack must be already set up in order for interrupts to be serviced, and interrupts must be enabled in order for the system timer-tick interrupt, which BIOS always uses at least to maintain the time-of-day count and which it initializes during POST, to be active and for the keyboard to work. The keyboard works even if the BIOS keyboard service is not called; keystrokes are received and placed in the 15-character type-ahead buffer maintained by BIOS.) The boot program must set up its own stack, because the size of the stack set up by BIOS is unknown and its location is likewise variable; although the boot program can investigate the default stack by examining SS:SP, it is easier and shorter to just unconditionally set up a new stack.<sup id="cite_ref-32" class="reference"><a href="#cite_note-32"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> </p><p>At boot time, all BIOS services are available, and the memory below address <code>0x00400</code> contains the <a href="/wiki/Interrupt_vector_table" title="Interrupt vector table">interrupt vector table</a>. BIOS POST has initialized the system timers, interrupt controller(s), DMA controller(s), and other motherboard/chipset hardware as necessary to bring all BIOS services to ready status. DRAM refresh for all system DRAM in conventional memory and extended memory, but not necessarily expanded memory, has been set up and is running. The <a href="/wiki/Interrupt_vector" class="mw-redirect" title="Interrupt vector">interrupt vectors</a> corresponding to the BIOS interrupts have been set to point at the appropriate entry points in the BIOS, hardware interrupt vectors for devices initialized by the BIOS have been set to point to the BIOS-provided ISRs, and some other interrupts, including ones that BIOS generates for programs to hook, have been set to a default dummy ISR that immediately returns. The BIOS maintains a reserved block of system RAM at addresses <code>0x00400–0x004FF</code> with various parameters initialized during the POST. All memory at and above address <code>0x00500</code> can be used by the boot program; it may even overwrite itself.<sup id="cite_ref-33" class="reference"><a href="#cite_note-33"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-34" class="reference"><a href="#cite_note-34"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Operating_system_services">Operating system services</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=11" title="Edit section: Operating system services"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The BIOS ROM is customized to the particular manufacturer's hardware, allowing low-level services (such as reading a keystroke or writing a sector of data to diskette) to be provided in a standardized way to programs, including operating systems. For example, an IBM PC might have either a monochrome or a color display adapter (using different display memory addresses and hardware), but a single, standard, BIOS <a href="/wiki/System_call" title="System call">system call</a> may be invoked to display a character at a specified position on the screen in <a href="/wiki/Text_mode" title="Text mode">text mode</a> or <a href="/wiki/All_points_addressable" class="mw-redirect" title="All points addressable">graphics mode</a>. </p><p>The BIOS provides a small <a href="/wiki/Library_(computing)" title="Library (computing)">library</a> of basic input/output functions to operate peripherals (such as the keyboard, rudimentary text and graphics display functions and so forth). When using MS-DOS, BIOS services could be accessed by an application program (or by MS-DOS) by executing an interrupt 13h <a href="/wiki/INT_(x86_instruction)" title="INT (x86 instruction)">interrupt instruction</a> to access disk functions, or by executing one of a number of other documented <a href="/wiki/BIOS_interrupt_call" title="BIOS interrupt call">BIOS interrupt calls</a> to access <a href="/wiki/Display_device" title="Display device">video display</a>, <a href="/wiki/Computer_keyboard" title="Computer keyboard">keyboard</a>, cassette, and other device functions. </p><p><a href="/wiki/Operating_system" title="Operating system">Operating systems</a> and executive software that are designed to supersede this basic firmware functionality provide replacement software interfaces to application software. Applications can also provide these services to themselves. This began even in the 1980s under <a href="/wiki/MS-DOS" title="MS-DOS">MS-DOS</a>, when programmers observed that using the BIOS video services for graphics display were very slow. To increase the speed of screen output, many programs bypassed the BIOS and programmed the video display hardware directly. Other graphics programmers, particularly but not exclusively in the <a href="/wiki/Demoscene" title="Demoscene">demoscene</a>, observed that there were technical capabilities of the PC display adapters that were not supported by the IBM BIOS and could not be taken advantage of without circumventing it. Since the AT-compatible BIOS ran in Intel <a href="/wiki/Real_mode" title="Real mode">real mode</a>, operating systems that ran in protected mode on 286 and later processors required hardware device drivers compatible with protected mode operation to replace BIOS services. </p><p>In modern PCs running modern <a href="/wiki/Operating_systems" class="mw-redirect" title="Operating systems">operating systems</a> (such as <a href="/wiki/Microsoft_Windows" title="Microsoft Windows">Windows</a> and <a href="/wiki/Linux" title="Linux">Linux</a>) the <a href="/wiki/BIOS_interrupt_calls" class="mw-redirect" title="BIOS interrupt calls">BIOS interrupt calls</a> are used only during booting and initial loading of operating systems. Before the operating system's first graphical screen is displayed, input and output are typically handled through BIOS. A boot menu such as the textual menu of Windows, which allows users to choose an operating system to boot, to boot into the <a href="/wiki/Safe_mode" title="Safe mode">safe mode</a>, or to use the last known good configuration, is displayed through BIOS and receives keyboard input through BIOS.<sup id="cite_ref-Booting_·_Linux_Inside_5-1" class="reference"><a href="#cite_note-Booting_·_Linux_Inside-5"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p><p>Many modern PCs can still boot and run legacy operating systems such as MS-DOS or DR-DOS that rely heavily on BIOS for their console and disk I/O, providing that the system has a BIOS, or a CSM-capable UEFI firmware. </p> <div class="mw-heading mw-heading3"><h3 id="Processor_microcode_updates">Processor microcode updates</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=12" title="Edit section: Processor microcode updates"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><a href="/wiki/Intel" title="Intel">Intel</a> processors have reprogrammable <a href="/wiki/Microcode" title="Microcode">microcode</a> since the <a href="/wiki/P6_(microarchitecture)" title="P6 (microarchitecture)">P6</a> microarchitecture.<sup id="cite_ref-Stiller_1996_35-0" class="reference"><a href="#cite_note-Stiller_1996-35"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Mueller-1_36-0" class="reference"><a href="#cite_note-Mueller-1-36"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-microcode-09_37-0" class="reference"><a href="#cite_note-microcode-09-37"><span class="cite-bracket">[</span>35<span class="cite-bracket">]</span></a></sup> <a href="/wiki/AMD" title="AMD">AMD</a> processors have reprogrammable microcode since the <a href="/wiki/K7_(microarchitecture)" class="mw-redirect" title="K7 (microarchitecture)">K7</a> microarchitecture. The BIOS contain patches to the processor microcode that fix errors in the initial processor microcode; microcode is loaded into processor's <a href="/wiki/Static_RAM" class="mw-redirect" title="Static RAM">SRAM</a> so reprogramming is not persistent, thus loading of microcode updates is performed each time the system is powered up. Without reprogrammable microcode, an expensive processor swap would be required;<sup id="cite_ref-Mueller-2_38-0" class="reference"><a href="#cite_note-Mueller-2-38"><span class="cite-bracket">[</span>36<span class="cite-bracket">]</span></a></sup> for example, the <a href="/wiki/Pentium_FDIV_bug" title="Pentium FDIV bug">Pentium FDIV bug</a> became an expensive fiasco for Intel as it required a <a href="/wiki/Product_recall" title="Product recall">product recall</a> because the original Pentium processor's defective microcode could not be reprogrammed. Operating systems can update <a href="/wiki/Main_processor" class="mw-redirect" title="Main processor">main processor</a> microcode also.<sup id="cite_ref-39" class="reference"><a href="#cite_note-39"><span class="cite-bracket">[</span>37<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-40" class="reference"><a href="#cite_note-40"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Identification"><span class="anchor" id="SLIC"></span>Identification</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=13" title="Edit section: Identification"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Some BIOSes contain a software licensing description table (SLIC), a digital signature placed inside the BIOS by the <a href="/wiki/Original_equipment_manufacturer" title="Original equipment manufacturer">original equipment manufacturer</a> (OEM), for example <a href="/wiki/Dell" title="Dell">Dell</a>. The SLIC is inserted into the ACPI data table and contains no active code.<sup id="cite_ref-guytechie-2010225_41-0" class="reference"><a href="#cite_note-guytechie-2010225-41"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-42" class="reference"><a href="#cite_note-42"><span class="cite-bracket">[</span>40<span class="cite-bracket">]</span></a></sup> </p><p>Computer manufacturers that distribute OEM versions of Microsoft Windows and Microsoft application software can use the SLIC to authenticate licensing to the OEM Windows Installation disk and system <a href="/wiki/Recovery_disc" title="Recovery disc">recovery disc</a> containing Windows software. Systems with a SLIC can be preactivated with an OEM product key, and they verify an XML formatted OEM certificate against the SLIC in the BIOS as a means of self-activating (see <a href="/wiki/System_Locked_Preinstallation" class="mw-redirect" title="System Locked Preinstallation">System Locked Preinstallation</a>, SLP). If a user performs a fresh install of Windows, they will need to have possession of both the OEM key (either SLP or COA) and the digital certificate for their SLIC in order to bypass activation.<sup id="cite_ref-guytechie-2010225_41-1" class="reference"><a href="#cite_note-guytechie-2010225-41"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup> This can be achieved if the user performs a restore using a pre-customised image provided by the OEM. Power users can copy the necessary certificate files from the OEM image, decode the SLP product key, then perform SLP activation manually. </p> <div class="mw-heading mw-heading3"><h3 id="Overclocking">Overclocking</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=14" title="Edit section: Overclocking"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Some BIOS implementations allow <a href="/wiki/Overclocking" title="Overclocking">overclocking</a>, an action in which the <a href="/wiki/Central_processing_unit" title="Central processing unit">CPU</a> is adjusted to a higher <a href="/wiki/Clock_rate" title="Clock rate">clock rate</a> than its manufacturer rating for guaranteed capability. Overclocking may, however, seriously compromise system reliability in insufficiently cooled computers and generally shorten component lifespan. Overclocking, when incorrectly performed, may also cause components to overheat so quickly that they mechanically destroy themselves.<sup id="cite_ref-43" class="reference"><a href="#cite_note-43"><span class="cite-bracket">[</span>41<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Modern_use">Modern use</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=15" title="Edit section: Modern use"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Some older <a href="/wiki/Operating_systems" class="mw-redirect" title="Operating systems">operating systems</a>, for example <a href="/wiki/MS-DOS" title="MS-DOS">MS-DOS</a>, rely on the BIOS to carry out most input/output tasks within the PC.<sup id="cite_ref-computing-basics-94_44-0" class="reference"><a href="#cite_note-computing-basics-94-44"><span class="cite-bracket">[</span>42<span class="cite-bracket">]</span></a></sup> </p><p>Calling <a href="/wiki/Real_mode" title="Real mode">real mode</a> BIOS services directly is inefficient for <a href="/wiki/Protected_mode" title="Protected mode">protected mode</a> (and <a href="/wiki/Long_mode" title="Long mode">long mode</a>) operating systems. <a href="/wiki/BIOS_interrupt_calls" class="mw-redirect" title="BIOS interrupt calls">BIOS interrupt calls</a> are not used by modern multitasking operating systems after they initially load. </p><p>In the 1990s, BIOS provided some <a href="/wiki/Protected_mode" title="Protected mode">protected mode</a> interfaces for <a href="/wiki/Microsoft_Windows" title="Microsoft Windows">Microsoft Windows</a> and <a href="/wiki/Unix-like" title="Unix-like">Unix-like</a> operating systems, such as <a href="/wiki/Advanced_Power_Management" title="Advanced Power Management">Advanced Power Management</a> (APM), <a href="/wiki/Plug_and_Play_BIOS" class="mw-redirect" title="Plug and Play BIOS">Plug and Play BIOS</a>, <a href="/wiki/Desktop_Management_Interface" title="Desktop Management Interface">Desktop Management Interface</a> (DMI), <a href="/wiki/VESA_BIOS_Extensions" title="VESA BIOS Extensions">VESA BIOS Extensions</a> (VBE), <a href="/wiki/E820" title="E820">e820</a> and <a href="/wiki/MultiProcessor_Specification" title="MultiProcessor Specification">MultiProcessor Specification</a> (MPS). Starting from the year 2000, most BIOSes provide <a href="/wiki/Advanced_Configuration_and_Power_Interface" class="mw-redirect" title="Advanced Configuration and Power Interface">ACPI</a>, <a href="/wiki/SMBIOS" class="mw-redirect" title="SMBIOS">SMBIOS</a>, <a href="/wiki/VBE" class="mw-redirect" title="VBE">VBE</a> and <a href="/wiki/E820" title="E820">e820</a> interfaces for modern operating systems.<sup id="cite_ref-45" class="reference"><a href="#cite_note-45"><span class="cite-bracket">[</span>43<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-46" class="reference"><a href="#cite_note-46"><span class="cite-bracket">[</span>44<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-47" class="reference"><a href="#cite_note-47"><span class="cite-bracket">[</span>45<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-48" class="reference"><a href="#cite_note-48"><span class="cite-bracket">[</span>46<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-49" class="reference"><a href="#cite_note-49"><span class="cite-bracket">[</span>47<span class="cite-bracket">]</span></a></sup> </p><p>After <a href="/wiki/Operating_systems" class="mw-redirect" title="Operating systems">operating systems</a> load, the <a href="/wiki/System_Management_Mode" title="System Management Mode">System Management Mode</a> code is still running in SMRAM. Since 2010, BIOS technology is in a transitional process toward <a href="/wiki/UEFI" title="UEFI">UEFI</a>.<sup id="cite_ref-Bradley_6-1" class="reference"><a href="#cite_note-Bradley-6"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Configuration">Configuration</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=16" title="Edit section: Configuration"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading3"><h3 id="Setup_utility">Setup utility</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=17" title="Edit section: Setup utility"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Historically, the BIOS in the IBM PC and XT had no built-in user interface. The BIOS versions in earlier PCs (XT-class) were not software configurable; instead, users set the options via <a href="/wiki/DIP_switch" title="DIP switch">DIP switches</a> on the motherboard. Later computers, including all IBM-compatibles with 80286 CPUs, had a battery-backed <a href="/wiki/Nonvolatile_BIOS_memory" title="Nonvolatile BIOS memory">nonvolatile BIOS memory</a> (CMOS RAM chip) that held BIOS settings.<sup id="cite_ref-CMOS_Battery_50-0" class="reference"><a href="#cite_note-CMOS_Battery-50"><span class="cite-bracket">[</span>48<span class="cite-bracket">]</span></a></sup> These settings, such as video-adapter type, memory size, and hard-disk parameters, could only be configured by running a configuration program from a disk, not built into the ROM. A special "reference diskette" was inserted in an <a href="/wiki/IBM_Personal_Computer/AT" class="mw-redirect" title="IBM Personal Computer/AT">IBM AT</a> to configure settings such as memory size.<sup id="cite_ref-51" class="reference"><a href="#cite_note-51"><span class="cite-bracket">[</span>49<span class="cite-bracket">]</span></a></sup> </p><p>Early BIOS versions did not have passwords or boot-device selection options. The BIOS was hard-coded to boot from the first floppy drive, or, if that failed, the first hard disk. Access control in early AT-class machines was by a physical keylock switch (which was not hard to defeat if the computer case could be opened). Anyone who could switch on the computer could boot it.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (March 2013)">citation needed</span></a></i>]</sup> </p><p>Later, 386-class computers started integrating the BIOS setup utility in the ROM itself, alongside the BIOS code; these computers usually boot into the BIOS setup utility if a certain key or key combination is pressed, otherwise the BIOS POST and boot process are executed. </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Award_BIOS_setup_utility.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/0/05/Award_BIOS_setup_utility.png/220px-Award_BIOS_setup_utility.png" decoding="async" width="220" height="138" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/05/Award_BIOS_setup_utility.png/330px-Award_BIOS_setup_utility.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/0/05/Award_BIOS_setup_utility.png/440px-Award_BIOS_setup_utility.png 2x" data-file-width="640" data-file-height="400" /></a><figcaption>Award BIOS setup utility on a standard PC</figcaption></figure> <p>A modern BIOS setup utility has a <a href="/wiki/Text_user_interface" class="mw-redirect" title="Text user interface">text user interface</a> (TUI) or <a href="/wiki/Graphical_user_interface" title="Graphical user interface">graphical user interface</a> (GUI) accessed by pressing a certain key on the keyboard when the PC starts. Usually, the key is advertised for short time during the early startup, for example "Press DEL to enter Setup". </p><p>The actual key depends on specific hardware. The settings key is most often <a href="/wiki/Delete_key" title="Delete key">Delete</a> (<a href="/wiki/Acer_Inc." title="Acer Inc.">Acer</a>, <a href="/wiki/ASRock" title="ASRock">ASRock</a>, <a href="/wiki/Asus" title="Asus">Asus</a> PC, <a href="/wiki/Elitegroup_Computer_Systems" title="Elitegroup Computer Systems">ECS</a>, <a href="/wiki/Gigabyte_Technology" title="Gigabyte Technology">Gigabyte</a>, <a href="/wiki/Micro-Star_International" title="Micro-Star International">MSI</a>, <a href="/wiki/ZOTAC" title="ZOTAC">Zotac</a>) and <a href="/wiki/Function_key" title="Function key">F2</a> (Asus motherboard, <a href="/wiki/Dell" title="Dell">Dell</a>, <a href="/wiki/Lenovo" title="Lenovo">Lenovo</a> laptop, <a href="/wiki/Origin_PC" title="Origin PC">Origin PC</a>, <a href="/wiki/Samsung" title="Samsung">Samsung</a>, <a href="/wiki/Toshiba" title="Toshiba">Toshiba</a>), but it can also be <a href="/wiki/Function_key" title="Function key">F1</a> (Lenovo desktop) and <a href="/wiki/Function_key" title="Function key">F10</a> (<a href="/wiki/Hewlett-Packard" title="Hewlett-Packard">HP</a>).<sup id="cite_ref-52" class="reference"><a href="#cite_note-52"><span class="cite-bracket">[</span>50<span class="cite-bracket">]</span></a></sup> </p><p>Features present in the BIOS setup utility typically include: </p> <ul><li>Configuring, enabling and disabling the hardware components</li> <li>Setting the <a href="/wiki/System_time" title="System time">system time</a></li> <li>Setting the boot order</li> <li>Setting various passwords, such as a password for securing access to the BIOS user interface and preventing malicious users from booting the system from unauthorized portable storage devices, or a password for booting the system</li></ul> <div class="mw-heading mw-heading3"><h3 id="Hardware_monitoring">Hardware monitoring</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=18" title="Edit section: Hardware monitoring"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Hardware_monitoring" class="mw-redirect" title="Hardware monitoring">Hardware monitoring</a></div> <p>A modern BIOS setup screen often features a <b>PC Health Status</b> or a <b>Hardware Monitoring</b> tab, which directly interfaces with a Hardware Monitor chip of the mainboard.<sup id="cite_ref-sensors-mmath_53-0" class="reference"><a href="#cite_note-sensors-mmath-53"><span class="cite-bracket">[</span>51<span class="cite-bracket">]</span></a></sup> This makes it possible to monitor CPU and <a href="/wiki/Computer_case" title="Computer case">chassis</a> temperature, the voltage provided by the <a href="/wiki/Power_supply_unit_(computer)" title="Power supply unit (computer)">power supply unit</a>, as well as monitor and <a href="/wiki/Computer_fan_control" title="Computer fan control">control the speed of the fans</a> connected to the motherboard. </p><p>Once the system is booted, hardware monitoring and <a href="/wiki/Computer_fan_control" title="Computer fan control">computer fan control</a> is normally done directly by the Hardware Monitor chip itself, which can be a separate chip, interfaced through <a href="/wiki/I%C2%B2C" title="I²C">I²C</a> or <a href="/wiki/System_Management_Bus" title="System Management Bus">SMBus</a>, or come as a part of a <a href="/wiki/Super_I/O" title="Super I/O">Super I/O</a> solution, interfaced through <a href="/wiki/Industry_Standard_Architecture" title="Industry Standard Architecture">Industry Standard Architecture</a> (ISA) or <a href="/wiki/Low_Pin_Count" title="Low Pin Count">Low Pin Count</a> (LPC).<sup id="cite_ref-ieee07_54-0" class="reference"><a href="#cite_note-ieee07-54"><span class="cite-bracket">[</span>52<span class="cite-bracket">]</span></a></sup> Some operating systems, like <a href="/wiki/NetBSD" title="NetBSD">NetBSD</a> with <a href="/wiki/Envsys" title="Envsys">envsys</a> and <a href="/wiki/OpenBSD" title="OpenBSD">OpenBSD</a> with sysctl <a href="/wiki/Hw.sensors" title="Hw.sensors">hw.sensors</a>, feature integrated interfacing with hardware monitors. </p><p>However, in some circumstances, the BIOS also provides the underlying information about hardware monitoring through <a href="/wiki/Advanced_Configuration_and_Power_Interface" class="mw-redirect" title="Advanced Configuration and Power Interface">ACPI</a>, in which case, the operating system may be using ACPI to perform hardware monitoring.<sup id="cite_ref-aibs.4_55-0" class="reference"><a href="#cite_note-aibs.4-55"><span class="cite-bracket">[</span>53<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-56" class="reference"><a href="#cite_note-56"><span class="cite-bracket">[</span>54<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Reprogramming"><span class="anchor" id="Flashing_the_BIOS"></span>Reprogramming</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=19" title="Edit section: Reprogramming"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:BIOS_replacement_kit.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b4/BIOS_replacement_kit.jpg/220px-BIOS_replacement_kit.jpg" decoding="async" width="220" height="170" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/b4/BIOS_replacement_kit.jpg/330px-BIOS_replacement_kit.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/b4/BIOS_replacement_kit.jpg/440px-BIOS_replacement_kit.jpg 2x" data-file-width="5187" data-file-height="4000" /></a><figcaption>BIOS replacement kit for a Dell 310 from the late 1980s. Included are two chips, a plastic holder for the chips, and a <a href="/wiki/IC_extractor" title="IC extractor">IC extractor</a>.</figcaption></figure> <p>In modern PCs the BIOS is stored in rewritable <a href="/wiki/EEPROM" title="EEPROM">EEPROM</a><sup id="cite_ref-57" class="reference"><a href="#cite_note-57"><span class="cite-bracket">[</span>55<span class="cite-bracket">]</span></a></sup> or <a href="/wiki/NOR_flash_memory" class="mw-redirect" title="NOR flash memory">NOR flash memory</a>,<sup id="cite_ref-58" class="reference"><a href="#cite_note-58"><span class="cite-bracket">[</span>56<span class="cite-bracket">]</span></a></sup> allowing the contents to be replaced and modified. This rewriting of the contents is sometimes termed <i>flashing.</i> It can be done by a special program, usually provided by the system's manufacturer, or at <a href="/wiki/Power-on_self-test" title="Power-on self-test">POST</a>, with a BIOS image in a hard drive or USB flash drive. A file containing such contents is sometimes termed "a BIOS image". A BIOS might be reflashed in order to upgrade to a newer version to fix bugs or provide improved performance or to support newer hardware. Some computers also support updating the BIOS via an update floppy disk or a special partition on the hard drive.<sup id="cite_ref-59" class="reference"><a href="#cite_note-59"><span class="cite-bracket">[</span>57<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Hardware">Hardware</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=20" title="Edit section: Hardware"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Elitegroup_761GX-M754_-_AMIBIOS_(American_Megatrends)_in_a_Winbond_W39V040APZ-5491.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/9/9a/Elitegroup_761GX-M754_-_AMIBIOS_%28American_Megatrends%29_in_a_Winbond_W39V040APZ-5491.jpg/220px-Elitegroup_761GX-M754_-_AMIBIOS_%28American_Megatrends%29_in_a_Winbond_W39V040APZ-5491.jpg" decoding="async" width="220" height="165" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/9a/Elitegroup_761GX-M754_-_AMIBIOS_%28American_Megatrends%29_in_a_Winbond_W39V040APZ-5491.jpg/330px-Elitegroup_761GX-M754_-_AMIBIOS_%28American_Megatrends%29_in_a_Winbond_W39V040APZ-5491.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/9a/Elitegroup_761GX-M754_-_AMIBIOS_%28American_Megatrends%29_in_a_Winbond_W39V040APZ-5491.jpg/440px-Elitegroup_761GX-M754_-_AMIBIOS_%28American_Megatrends%29_in_a_Winbond_W39V040APZ-5491.jpg 2x" data-file-width="3256" data-file-height="2442" /></a><figcaption><a href="/wiki/American_Megatrends" title="American Megatrends">American Megatrends</a> BIOS 686. This BIOS chip is housed in a <a href="/wiki/Plastic_leaded_chip_carrier" class="mw-redirect" title="Plastic leaded chip carrier">PLCC</a> package in a socket.</figcaption></figure> <p>The original IBM PC BIOS (and cassette BASIC) was stored on mask-programmed <a href="/wiki/Read-only_memory" title="Read-only memory">read-only memory</a> (ROM) chips in sockets on the motherboard. ROMs could be replaced,<sup id="cite_ref-60" class="reference"><a href="#cite_note-60"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup> but not altered, by users. To allow for updates, many compatible computers used re-programmable BIOS memory devices such as <a href="/wiki/EPROM" title="EPROM">EPROM</a>, <a href="/wiki/EEPROM" title="EEPROM">EEPROM</a> and later <a href="/wiki/Flash_memory" title="Flash memory">flash memory</a> (usually <a href="/wiki/NOR_flash" class="mw-redirect" title="NOR flash">NOR flash</a>) devices. According to Robert Braver, the president of the BIOS manufacturer Micro Firmware, <b>Flash BIOS</b> chips became common around 1995 because the electrically erasable PROM (EEPROM) chips are cheaper and easier to program than standard <a href="/wiki/Ultraviolet" title="Ultraviolet">ultraviolet</a> erasable PROM (<a href="/wiki/EPROM" title="EPROM">EPROM</a>) chips. Flash chips are programmed (and re-programmed) in-circuit, while EPROM chips need to be removed from the motherboard for re-programming.<sup id="cite_ref-smart-computing-97_61-0" class="reference"><a href="#cite_note-smart-computing-97-61"><span class="cite-bracket">[</span>59<span class="cite-bracket">]</span></a></sup> BIOS versions are upgraded to take advantage of newer versions of hardware and to correct bugs in previous revisions of BIOSes.<sup id="cite_ref-smart-computing-96_62-0" class="reference"><a href="#cite_note-smart-computing-96-62"><span class="cite-bracket">[</span>60<span class="cite-bracket">]</span></a></sup> </p><p>Beginning with the IBM AT, PCs supported a hardware clock settable through BIOS. It had a century bit which allowed for manually changing the century when the year 2000 happened. Most BIOS revisions created in 1995 and nearly all BIOS revisions in 1997 supported <a href="/wiki/Year_2000_problem" title="Year 2000 problem">the year 2000</a> by setting the century bit automatically when the clock rolled past midnight, 31 December 1999.<sup id="cite_ref-smart-somputing-99_63-0" class="reference"><a href="#cite_note-smart-somputing-99-63"><span class="cite-bracket">[</span>61<span class="cite-bracket">]</span></a></sup> </p><p>The first flash chips were attached to the <a href="/wiki/Industry_Standard_Architecture" title="Industry Standard Architecture">ISA bus</a>. Starting in 1998, the BIOS flash moved to the <a href="/wiki/Low_Pin_Count" title="Low Pin Count">LPC</a> bus, following a new standard implementation known as "firmware hub" (FWH). In 2005, the BIOS flash memory moved to the <a href="/wiki/Serial_Peripheral_Interface" title="Serial Peripheral Interface">SPI</a> bus.<sup id="cite_ref-64" class="reference"><a href="#cite_note-64"><span class="cite-bracket">[</span>62<span class="cite-bracket">]</span></a></sup> </p><p>The size of the BIOS, and the capacity of the ROM, EEPROM, or other media it may be stored on, has increased over time as new features have been added to the code; BIOS versions now exist with sizes up to 32 megabytes. For contrast, the original IBM PC BIOS was contained in an 8 KB mask ROM. Some modern motherboards are including even bigger NAND <a href="/wiki/Flash_memory" title="Flash memory">flash memory</a> ICs on board which are capable of storing whole compact operating systems, such as some <a href="/wiki/Linux_distribution" title="Linux distribution">Linux distributions</a>. For example, some ASUS notebooks included <a href="/wiki/Splashtop_OS" title="Splashtop OS">Splashtop OS</a> embedded into their NAND flash memory ICs.<sup id="cite_ref-geek-splashtop_65-0" class="reference"><a href="#cite_note-geek-splashtop-65"><span class="cite-bracket">[</span>63<span class="cite-bracket">]</span></a></sup> However, the idea of including an operating system along with BIOS in the ROM of a PC is not new; in the 1980s, Microsoft offered a ROM option for MS-DOS, and it was included in the ROMs of some PC clones such as the <a href="/wiki/Tandy_1000#Tandy_1000_HX_.26_TX" title="Tandy 1000">Tandy 1000 HX</a>. </p><p>Another type of firmware chip was found on the IBM PC AT and early compatibles. In the AT, the <a href="/wiki/Keyboard_controller_(computing)" title="Keyboard controller (computing)">keyboard interface</a> was controlled by a <a href="/wiki/Microcontroller" title="Microcontroller">microcontroller</a> with its own programmable memory. On the IBM AT, that was a 40-pin socketed device, while some manufacturers used an EPROM version of this chip which resembled an EPROM. This controller was also assigned the <a href="/wiki/A20_gate" class="mw-redirect" title="A20 gate">A20 gate</a> function to manage memory above the one-megabyte range; occasionally an upgrade of this "keyboard BIOS" was necessary to take advantage of software that could use upper memory.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (March 2013)">citation needed</span></a></i>]</sup> </p><p>The BIOS may contain components such as the <a href="/wiki/Memory_Reference_Code" title="Memory Reference Code">Memory Reference Code</a> (MRC), which is responsible for the memory initialization (e.g. <a href="/wiki/Serial_presence_detect" title="Serial presence detect">SPD</a> and <a href="/wiki/Memory_timings" title="Memory timings">memory timings</a> initialization).<sup id="cite_ref-Life_and_Times_66-0" class="reference"><a href="#cite_note-Life_and_Times-66"><span class="cite-bracket">[</span>64<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: 8">: 8 </span></sup><sup id="cite_ref-Hilber_67-0" class="reference"><a href="#cite_note-Hilber-67"><span class="cite-bracket">[</span>65<span class="cite-bracket">]</span></a></sup> </p><p>Modern BIOS<sup id="cite_ref-68" class="reference"><a href="#cite_note-68"><span class="cite-bracket">[</span>66<span class="cite-bracket">]</span></a></sup> includes <a href="/wiki/Intel_Management_Engine" title="Intel Management Engine">Intel Management Engine</a> or <a href="/wiki/AMD_Platform_Security_Processor" title="AMD Platform Security Processor">AMD Platform Security Processor</a> firmware. </p> <div class="mw-heading mw-heading2"><h2 id="Vendors_and_products"><span class="anchor" id="COMPARISON"></span>Vendors and products</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=21" title="Edit section: Vendors and products"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <table class="wikitable floatright" style="margin-left: 2em;"> <caption>Comparison of different BIOS implementations </caption> <tbody><tr> <th>Company </th> <td><a href="/wiki/Award_Software" title="Award Software">AwardBIOS</a> </td> <td><a href="/wiki/American_Megatrends" title="American Megatrends">AMIBIOS</a> </td> <td><a href="/wiki/Insyde_Software" title="Insyde Software">Insyde</a> </td> <td><a href="/wiki/SeaBIOS" title="SeaBIOS">SeaBIOS</a> </td></tr> <tr> <th>License </th> <td style="background: #E7E7FF; color:black; vertical-align: middle; text-align: center;" class="table-proprietary"><a href="/wiki/Proprietary_software" title="Proprietary software">Proprietary</a> </td> <td style="background: #E7E7FF; color:black; vertical-align: middle; text-align: center;" class="table-proprietary"><a href="/wiki/Proprietary_software" title="Proprietary software">Proprietary</a> </td> <td style="background: #E7E7FF; color:black; vertical-align: middle; text-align: center;" class="table-proprietary"><a href="/wiki/Proprietary_software" title="Proprietary software">Proprietary</a> </td> <td style="background: #9EFF9E; color:black; vertical-align: middle; text-align: center;" class="active table-active"><a href="/wiki/GNU_Lesser_General_Public_License" title="GNU Lesser General Public License">LGPL</a> v3 </td></tr> <tr> <th>Maintained / developed </th> <td style="background: #FFDFFF; color:black; vertical-align: middle; text-align: center;" class="dropped table-dropped">Terminated </td> <td style="background: #FFDFFF; color:black; vertical-align: middle; text-align: center;" class="dropped table-dropped">Terminated </td> <td style="background: #FFDFFF; color:black; vertical-align: middle; text-align: center;" class="dropped table-dropped">Terminated </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td></tr> <tr> <th><a href="/wiki/32-bit_computing" title="32-bit computing">32-bit</a> PCI BIOS calls </th> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td></tr> <tr> <th><abbr title="Advanced Host Controller Interface">AHCI</abbr> </th> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td></tr> <tr> <th><abbr title="Advanced Power Management">APM</abbr> </th> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes <small>(1.2)</small> </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes <small>(1.2)</small> </td></tr> <tr> <th><abbr title="BIOS Boot Specification">BBS</abbr> </th> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td></tr> <tr> <th>Boot menu </th> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td></tr> <tr> <th>Compression </th> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes <small>(<a href="/wiki/LHA_(file_format)" title="LHA (file format)">LHA</a><sup id="cite_ref-prozessor-patches_69-0" class="reference"><a href="#cite_note-prozessor-patches-69"><span class="cite-bracket">[</span>67<span class="cite-bracket">]</span></a></sup>)</small> </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes <small>(LHA)</small> </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes <small>(RLE)</small> </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes <small>(LZMA)</small> </td></tr> <tr> <th>CMOS </th> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td></tr> <tr> <th><abbr title="Enhanced Disk Drive">EDD</abbr> </th> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td></tr> <tr> <th><abbr title="Extended System Configuration Data">ESCD</abbr> </th> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background: var(--background-color-interactive, #EEE); color: var(--color-base, black); vertical-align: middle; white-space: nowrap; text-align: center;" class="table-Unknown">? </td> <td style="background:#FFC7C7;color:black;vertical-align:middle;text-align:center;" class="table-no">No </td></tr> <tr> <th>Flash from ROM </th> <td style="background: var(--background-color-interactive, #EEE); color: var(--color-base, black); vertical-align: middle; white-space: nowrap; text-align: center;" class="table-Unknown">? </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background: var(--background-color-interactive, #EEE); color: var(--color-base, black); vertical-align: middle; white-space: nowrap; text-align: center;" class="table-Unknown">? </td> <td style="background:#FFC7C7;color:black;vertical-align:middle;text-align:center;" class="table-no">No </td></tr> <tr> <th>Language </th> <td>Assembly </td> <td>Assembly </td> <td>Assembly </td> <td><a href="/wiki/C_(programming_language)" title="C (programming language)">C</a> </td></tr> <tr> <th><abbr title="Logical Block Addressing">LBA</abbr> </th> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes <small>(48)</small> </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes <small>(48)</small> </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes <small>(48)</small> </td></tr> <tr> <th>MultiProcessor Specification </th> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td></tr> <tr> <th>Option ROM </th> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td></tr> <tr> <th>Password </th> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#FFC7C7;color:black;vertical-align:middle;text-align:center;" class="table-no">No </td></tr> <tr> <th><abbr title="Post Memory Manager">PMM</abbr> </th> <td style="background: var(--background-color-interactive, #EEE); color: var(--color-base, black); vertical-align: middle; white-space: nowrap; text-align: center;" class="table-Unknown">? </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background: var(--background-color-interactive, #EEE); color: var(--color-base, black); vertical-align: middle; white-space: nowrap; text-align: center;" class="table-Unknown">? </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td></tr> <tr> <th>Setup screen </th> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#FFC7C7;color:black;vertical-align:middle;text-align:center;" class="table-no">No </td></tr> <tr> <th><abbr title="System Management BIOS">SMBIOS</abbr> </th> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td></tr> <tr> <th>Splash screen </th> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes <small>(EPA)<sup id="cite_ref-70" class="reference"><a href="#cite_note-70"><span class="cite-bracket">[</span>68<span class="cite-bracket">]</span></a></sup></small> </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes <small>(<a href="/wiki/PCX" title="PCX">PCX</a>)</small> </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes <small>(BMP, JPG)</small> </td></tr> <tr> <th><abbr title="Trusted Platform Module">TPM</abbr> </th> <td style="background: var(--background-color-interactive, #EEE); color: var(--color-base, black); vertical-align: middle; white-space: nowrap; text-align: center;" class="table-Unknown">Unknown </td> <td style="background: var(--background-color-interactive, #EEE); color: var(--color-base, black); vertical-align: middle; white-space: nowrap; text-align: center;" class="table-Unknown">Unknown </td> <td style="background: var(--background-color-interactive, #EEE); color: var(--color-base, black); vertical-align: middle; white-space: nowrap; text-align: center;" class="table-Unknown">Unknown </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Some </td></tr> <tr> <th><a href="/wiki/USB" title="USB">USB</a> booting </th> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td></tr> <tr> <th>USB hub </th> <td style="background: var(--background-color-interactive, #EEE); color: var(--color-base, black); vertical-align: middle; white-space: nowrap; text-align: center;" class="table-Unknown">? </td> <td style="background: var(--background-color-interactive, #EEE); color: var(--color-base, black); vertical-align: middle; white-space: nowrap; text-align: center;" class="table-Unknown">? </td> <td style="background: var(--background-color-interactive, #EEE); color: var(--color-base, black); vertical-align: middle; white-space: nowrap; text-align: center;" class="table-Unknown">? </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td></tr> <tr> <th>USB keyboard </th> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td></tr> <tr> <th>USB mouse </th> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td></tr></tbody></table> <p>IBM published the entire listings of the BIOS for its original PC, PC XT, PC AT, and other contemporary PC models, in an appendix of the <i>IBM PC Technical Reference Manual</i> for each machine type. The effect of the publication of the BIOS listings is that anyone can see exactly what a definitive BIOS does and how it does it. </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Compaq_Portable_386_BIOS.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/f/fc/Compaq_Portable_386_BIOS.jpg/220px-Compaq_Portable_386_BIOS.jpg" decoding="async" width="220" height="124" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/fc/Compaq_Portable_386_BIOS.jpg/330px-Compaq_Portable_386_BIOS.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/fc/Compaq_Portable_386_BIOS.jpg/440px-Compaq_Portable_386_BIOS.jpg 2x" data-file-width="4032" data-file-height="2268" /></a><figcaption><a href="/wiki/Compaq_Portable" title="Compaq Portable">Compaq Portable</a> 386 BIOS</figcaption></figure> <p>In May 1984, <a href="/wiki/Phoenix_Technologies" title="Phoenix Technologies">Phoenix Software Associates</a> released its first ROM-BIOS. This BIOS enabled OEMs to build essentially fully compatible clones without having to reverse-engineer the IBM PC BIOS themselves, as Compaq had done for the <a href="/wiki/Compaq_Portable" title="Compaq Portable">Portable</a>; it also helped fuel the growth in the PC-compatibles industry and sales of non-IBM versions of DOS.<sup id="cite_ref-71" class="reference"><a href="#cite_note-71"><span class="cite-bracket">[</span>69<span class="cite-bracket">]</span></a></sup> The first <a href="/wiki/American_Megatrends" title="American Megatrends">American Megatrends</a> (AMI) BIOS was released in 1986. </p><p>New standards grafted onto the BIOS are usually without complete public documentation or any BIOS listings. As a result, it is not as easy to learn the intimate details about the many non-IBM additions to BIOS as about the core BIOS services. </p><p>Many PC motherboard suppliers licensed the BIOS "core" and toolkit from a commercial third party, known as an "independent BIOS vendor" or IBV. The motherboard manufacturer then customized this BIOS to suit its own hardware. For this reason, updated BIOSes are normally obtained directly from the motherboard manufacturer. Major IBVs included <a href="/wiki/American_Megatrends" title="American Megatrends">American Megatrends</a> (AMI), <a href="/wiki/Insyde_Software" title="Insyde Software">Insyde Software</a>, <a href="/wiki/Phoenix_Technologies" title="Phoenix Technologies">Phoenix Technologies</a>, and Byosoft. Microid Research and <a href="/wiki/Award_Software" title="Award Software">Award Software</a> were acquired by <a href="/wiki/Phoenix_Technologies" title="Phoenix Technologies">Phoenix Technologies</a> in 1998; Phoenix later phased out the Award brand name (although Award Software is still credited in newer AwardBIOS versions and in UEFI firmwares).<sup class="noprint Inline-Template" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Manual_of_Style/Dates_and_numbers#Chronological_items" title="Wikipedia:Manual of Style/Dates and numbers"><span title="The time period mentioned near this tag is ambiguous. (June 2024)">when?</span></a></i>]</sup> <a href="/wiki/General_Software" title="General Software">General Software</a>, which was also acquired by Phoenix in 2007, sold BIOS for embedded systems based on Intel processors. </p><p><a href="/wiki/SeaBIOS" title="SeaBIOS">SeaBIOS</a> is an open-source BIOS implementation. </p> <div class="mw-heading mw-heading2"><h2 id="Open-source_BIOS_replacements">Open-source BIOS replacements</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=22" title="Edit section: Open-source BIOS replacements"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The open-source community increased their effort to develop a replacement for proprietary BIOSes and their future incarnations with an open-sourced counterparts. <a href="/wiki/Open_Firmware" title="Open Firmware">Open Firmware</a> was an early attempt to make an open specification for boot firmware. It was initially endorsed by IEEE in its <i>IEEE 1275-1994</i> standard but was withdrawn in 2005.<sup id="cite_ref-72" class="reference"><a href="#cite_note-72"><span class="cite-bracket">[</span>70<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-73" class="reference"><a href="#cite_note-73"><span class="cite-bracket">[</span>71<span class="cite-bracket">]</span></a></sup> Later examples include the <a href="/wiki/OpenBIOS" title="OpenBIOS">OpenBIOS</a>, <a href="/wiki/Coreboot" title="Coreboot">coreboot</a> and <a href="/wiki/Libreboot" title="Libreboot">libreboot</a> projects. <a href="/wiki/Advanced_Micro_Devices" class="mw-redirect" title="Advanced Micro Devices">AMD</a> provided product specifications for some chipsets using coreboot, and <a href="/wiki/Google" title="Google">Google</a> is sponsoring the project. <a href="/wiki/Motherboard" title="Motherboard">Motherboard</a> manufacturer <a href="/wiki/Tyan" title="Tyan">Tyan</a> offers <a href="/wiki/Coreboot" title="Coreboot">coreboot</a> next to the standard BIOS with their <a href="/wiki/Opteron" title="Opteron">Opteron</a> line of motherboards. </p> <div class="mw-heading mw-heading2"><h2 id="Security"><span class="anchor" id="MEBROMI"></span><span class="anchor" id="DualBIOS"></span>Security</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=23" title="Edit section: Security"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1251242444">.mw-parser-output .ambox{border:1px solid #a2a9b1;border-left:10px solid #36c;background-color:#fbfbfb;box-sizing:border-box}.mw-parser-output .ambox+link+.ambox,.mw-parser-output .ambox+link+style+.ambox,.mw-parser-output .ambox+link+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+style+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+link+.ambox{margin-top:-1px}html body.mediawiki .mw-parser-output .ambox.mbox-small-left{margin:4px 1em 4px 0;overflow:hidden;width:238px;border-collapse:collapse;font-size:88%;line-height:1.25em}.mw-parser-output .ambox-speedy{border-left:10px solid #b32424;background-color:#fee7e6}.mw-parser-output .ambox-delete{border-left:10px solid #b32424}.mw-parser-output .ambox-content{border-left:10px solid #f28500}.mw-parser-output .ambox-style{border-left:10px solid #fc3}.mw-parser-output .ambox-move{border-left:10px solid #9932cc}.mw-parser-output .ambox-protection{border-left:10px solid #a2a9b1}.mw-parser-output .ambox .mbox-text{border:none;padding:0.25em 0.5em;width:100%}.mw-parser-output .ambox .mbox-image{border:none;padding:2px 0 2px 0.5em;text-align:center}.mw-parser-output .ambox .mbox-imageright{border:none;padding:2px 0.5em 2px 0;text-align:center}.mw-parser-output .ambox .mbox-empty-cell{border:none;padding:0;width:1px}.mw-parser-output .ambox .mbox-image-div{width:52px}@media(min-width:720px){.mw-parser-output .ambox{margin:0 10%}}@media print{body.ns-0 .mw-parser-output .ambox{display:none!important}}</style><table class="box-More_citations_needed_section plainlinks metadata ambox ambox-content ambox-Refimprove" role="presentation"><tbody><tr><td class="mbox-image"><div class="mbox-image-div"><span typeof="mw:File"><a href="/wiki/File:Question_book-new.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/50px-Question_book-new.svg.png" decoding="async" width="50" height="39" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/75px-Question_book-new.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/100px-Question_book-new.svg.png 2x" data-file-width="512" data-file-height="399" /></a></span></div></td><td class="mbox-text"><div class="mbox-text-span">This section <b>needs additional citations for <a href="/wiki/Wikipedia:Verifiability" title="Wikipedia:Verifiability">verification</a></b>.<span class="hide-when-compact"> Please help <a href="/wiki/Special:EditPage/BIOS" title="Special:EditPage/BIOS">improve this article</a> by <a href="/wiki/Help:Referencing_for_beginners" title="Help:Referencing for beginners">adding citations to reliable sources</a> in this section. Unsourced material may be challenged and removed.</span> <span class="date-container"><i>(<span class="date">March 2019</span>)</i></span><span class="hide-when-compact"><i> (<small><a href="/wiki/Help:Maintenance_template_removal" title="Help:Maintenance template removal">Learn how and when to remove this message</a></small>)</i></span></div></td></tr></tbody></table> <figure typeof="mw:File/Thumb"><a href="/wiki/File:Qfj32gel%C3%B6tet.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/5/5c/Qfj32gel%C3%B6tet.jpg/332px-Qfj32gel%C3%B6tet.jpg" decoding="async" width="332" height="148" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/5c/Qfj32gel%C3%B6tet.jpg/498px-Qfj32gel%C3%B6tet.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/5c/Qfj32gel%C3%B6tet.jpg/664px-Qfj32gel%C3%B6tet.jpg 2x" data-file-width="2337" data-file-height="1045" /></a><figcaption><a href="/wiki/Gigabyte_Technology" title="Gigabyte Technology">Gigabyte</a> DualBIOS <a href="/wiki/Plastic-leaded_chip_carrier" class="mw-redirect" title="Plastic-leaded chip carrier">PLCC</a>32</figcaption></figure> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Bios_chip-2011-04-11.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/f/f7/Bios_chip-2011-04-11.jpg/220px-Bios_chip-2011-04-11.jpg" decoding="async" width="220" height="171" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/f7/Bios_chip-2011-04-11.jpg/330px-Bios_chip-2011-04-11.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/f7/Bios_chip-2011-04-11.jpg/440px-Bios_chip-2011-04-11.jpg 2x" data-file-width="2640" data-file-height="2048" /></a><figcaption>A detached BIOS chip</figcaption></figure> <p><a href="/wiki/EEPROM" title="EEPROM">EEPROM</a> and <a href="/wiki/Flash_memory" title="Flash memory">flash memory</a> chips are advantageous because they can be easily updated by the user; it is customary for hardware manufacturers to issue BIOS updates to upgrade their products, improve compatibility and remove <a href="/wiki/Software_bug" title="Software bug">bugs</a>. However, this advantage had the risk that an improperly executed or aborted BIOS update could render the computer or device unusable. To avoid these situations, more recent BIOSes use a "boot block"; a portion of the BIOS which runs first and must be updated separately. This code verifies if the rest of the BIOS is intact (using <a href="/wiki/Hash_function" title="Hash function">hash</a> <a href="/wiki/Checksum" title="Checksum">checksums</a> or other methods) before transferring control to it. If the boot block detects any corruption in the main BIOS, it will typically warn the user that a recovery process must be initiated by booting from <a href="/wiki/Removable_media" title="Removable media">removable media</a> (floppy, CD or USB flash drive) so the user can try flashing the BIOS again. Some <a href="/wiki/Motherboard" title="Motherboard">motherboards</a> have a <i>backup</i> BIOS (sometimes referred to as DualBIOS boards) to recover from BIOS corruptions. </p><p>There are at least five known viruses that attack the BIOS. Two of which were for demonstration purposes. The first one found in the wild was <i>Mebromi</i>, targeting Chinese users. </p><p>The first BIOS virus was BIOS Meningitis, which instead of erasing BIOS chips it infected them. BIOS Meningitis was relatively harmless, compared to a virus like <a href="/wiki/CIH_(computer_virus)" title="CIH (computer virus)">CIH</a>. </p><p>The second BIOS virus was <a href="/wiki/CIH_(computer_virus)" title="CIH (computer virus)">CIH</a>, also known as the "Chernobyl Virus", which was able to erase flash ROM BIOS content on compatible chipsets. CIH appeared in mid-1998 and became active in April 1999. Often, infected computers could no longer boot, and people had to remove the flash ROM IC from the motherboard and reprogram it. CIH targeted the then-widespread Intel i430TX motherboard chipset and took advantage of the fact that the <a href="/wiki/Windows_9x" title="Windows 9x">Windows 9x</a> operating systems, also widespread at the time, allowed direct hardware access to all programs. </p><p>Modern systems are not vulnerable to CIH because of a variety of chipsets being used which are incompatible with the Intel i430TX chipset, and also other flash ROM IC types. There is also extra protection from accidental BIOS rewrites in the form of boot blocks which are protected from accidental overwrite or dual and quad BIOS equipped systems which may, in the event of a crash, use a backup BIOS. Also, all modern operating systems such as <a href="/wiki/FreeBSD" title="FreeBSD">FreeBSD</a>, <a href="/wiki/Linux" title="Linux">Linux</a>, <a href="/wiki/MacOS" title="MacOS">macOS</a>, <a href="/wiki/Windows_NT" title="Windows NT">Windows NT</a>-based Windows OS like <a href="/wiki/Windows_2000" title="Windows 2000">Windows 2000</a>, <a href="/wiki/Windows_XP" title="Windows XP">Windows XP</a> and newer, do not allow <a href="/wiki/Protection_ring" title="Protection ring">user-mode</a> programs to have direct hardware access using a <a href="/wiki/Hardware_Abstraction_Layer" class="mw-redirect" title="Hardware Abstraction Layer">hardware abstraction layer</a>.<sup id="cite_ref-74" class="reference"><a href="#cite_note-74"><span class="cite-bracket">[</span>72<span class="cite-bracket">]</span></a></sup> </p><p>As a result, as of 2008, CIH has become essentially harmless, at worst causing annoyance by infecting executable files and triggering antivirus software. Other BIOS viruses remain possible, however;<sup id="cite_ref-Yam_75-0" class="reference"><a href="#cite_note-Yam-75"><span class="cite-bracket">[</span>73<span class="cite-bracket">]</span></a></sup> since most Windows home users without Windows Vista/7's UAC run all applications with administrative privileges, a modern CIH-like virus could in principle still gain access to hardware without first using an exploit.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (March 2019)">citation needed</span></a></i>]</sup> The operating system <a href="/wiki/OpenBSD" title="OpenBSD">OpenBSD</a> prevents all users from having this access and the grsecurity patch for the Linux kernel also prevents this direct hardware access by default, the difference being an attacker requiring a much more difficult kernel level exploit or reboot of the machine.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (March 2019)">citation needed</span></a></i>]</sup> </p><p>The third BIOS virus was a technique presented by John Heasman, principal security consultant for UK-based Next-Generation Security Software. In 2006, at the Black Hat Security Conference, he showed how to elevate privileges and read physical memory, using malicious procedures that replaced normal <a href="/wiki/Advanced_Configuration_and_Power_Interface" class="mw-redirect" title="Advanced Configuration and Power Interface">ACPI</a> functions stored in flash memory.<sup id="cite_ref-76" class="reference"><a href="#cite_note-76"><span class="cite-bracket">[</span>74<span class="cite-bracket">]</span></a></sup> </p><p>The fourth BIOS virus was a technique called "Persistent BIOS infection." It appeared in 2009 at the CanSecWest Security Conference in Vancouver, and at the SyScan Security Conference in Singapore. Researchers <a href="/w/index.php?title=Anibal_Sacco&action=edit&redlink=1" class="new" title="Anibal Sacco (page does not exist)">Anibal Sacco</a><sup id="cite_ref-AutoTU-1_77-0" class="reference"><a href="#cite_note-AutoTU-1-77"><span class="cite-bracket">[</span>75<span class="cite-bracket">]</span></a></sup> and Alfredo Ortega, from Core Security Technologies, demonstrated how to insert malicious code into the decompression routines in the BIOS, allowing for nearly full control of the PC at start-up, even before the operating system is booted. The proof-of-concept does not exploit a flaw in the BIOS implementation, but only involves the normal BIOS flashing procedures. Thus, it requires physical access to the machine, or for the user to be root. Despite these requirements, Ortega underlined the profound implications of his and Sacco's discovery: "We can patch a driver to drop a fully working <a href="/wiki/Rootkit" title="Rootkit">rootkit</a>. We even have a little code that can remove or disable antivirus."<sup id="cite_ref-Fisher_78-0" class="reference"><a href="#cite_note-Fisher-78"><span class="cite-bracket">[</span>76<span class="cite-bracket">]</span></a></sup> </p><p>Mebromi is a <a href="/wiki/Trojan_horse_(computing)" title="Trojan horse (computing)">trojan</a> which targets computers with <a href="/wiki/AwardBIOS" class="mw-redirect" title="AwardBIOS">AwardBIOS</a>, <a href="/wiki/Microsoft_Windows" title="Microsoft Windows">Microsoft Windows</a>, and <a href="/wiki/Antivirus_software" title="Antivirus software">antivirus software</a> from two Chinese companies: Rising Antivirus and Jiangmin KV Antivirus.<sup id="cite_ref-Giuliani_79-0" class="reference"><a href="#cite_note-Giuliani-79"><span class="cite-bracket">[</span>77<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-BMW_80-0" class="reference"><a href="#cite_note-BMW-80"><span class="cite-bracket">[</span>78<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Yuan_81-0" class="reference"><a href="#cite_note-Yuan-81"><span class="cite-bracket">[</span>79<span class="cite-bracket">]</span></a></sup> Mebromi installs a rootkit which infects the <a href="/wiki/Master_boot_record" title="Master boot record">Master boot record</a>. </p><p>In a December 2013 interview with <i><a href="/wiki/60_Minutes" title="60 Minutes">60 Minutes</a></i>, Deborah Plunkett, Information Assurance Director for the US <a href="/wiki/National_Security_Agency" title="National Security Agency">National Security Agency</a> claimed the NSA had uncovered and thwarted a possible BIOS attack by a foreign nation state, targeting the US financial system.<sup id="cite_ref-cbs-news-60-minutes_82-0" class="reference"><a href="#cite_note-cbs-news-60-minutes-82"><span class="cite-bracket">[</span>80<span class="cite-bracket">]</span></a></sup> The program cited anonymous sources alleging it was a Chinese plot.<sup id="cite_ref-cbs-news-60-minutes_82-1" class="reference"><a href="#cite_note-cbs-news-60-minutes-82"><span class="cite-bracket">[</span>80<span class="cite-bracket">]</span></a></sup> However follow-up articles in <i><a href="/wiki/The_Guardian" title="The Guardian">The Guardian</a>,</i><sup id="cite_ref-Ackerman_83-0" class="reference"><a href="#cite_note-Ackerman-83"><span class="cite-bracket">[</span>81<span class="cite-bracket">]</span></a></sup> <i><a href="/wiki/The_Atlantic" title="The Atlantic">The Atlantic</a>,</i><sup id="cite_ref-84" class="reference"><a href="#cite_note-84"><span class="cite-bracket">[</span>82<span class="cite-bracket">]</span></a></sup> <i><a href="/wiki/Wired_(magazine)" title="Wired (magazine)">Wired</a></i><sup id="cite_ref-85" class="reference"><a href="#cite_note-85"><span class="cite-bracket">[</span>83<span class="cite-bracket">]</span></a></sup> and <i><a href="/wiki/The_Register" title="The Register">The Register</a></i><sup id="cite_ref-86" class="reference"><a href="#cite_note-86"><span class="cite-bracket">[</span>84<span class="cite-bracket">]</span></a></sup> refuted the NSA's claims. </p><p>Newer Intel platforms have <a href="/wiki/Intel_Boot_Guard" class="mw-redirect" title="Intel Boot Guard">Intel Boot Guard</a> (IBG) technology enabled, this technology will check the BIOS digital signature at startup, and the IBG public key is fused into the <a href="/wiki/Platform_Controller_Hub" title="Platform Controller Hub">PCH</a>. End users can't disable this function. </p> <div class="mw-heading mw-heading2"><h2 id="Alternatives_and_successors">Alternatives and successors</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=24" title="Edit section: Alternatives and successors"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">For comparable software on other computer systems, see <a href="/wiki/Booting" title="Booting">booting</a>.</div> <p><a href="/wiki/UEFI" title="UEFI">Unified Extensible Firmware Interface</a> (UEFI) supplements the BIOS in many new machines. Initially written for the <a href="/wiki/Intel_Itanium_architecture" class="mw-redirect" title="Intel Itanium architecture">Intel Itanium architecture</a>, UEFI is now available for <a href="/wiki/X86" title="X86">x86</a> and <a href="/wiki/ARM_architecture_family" title="ARM architecture family">Arm</a> platforms; the specification development is driven by the <a href="/wiki/Unified_EFI_Forum" class="mw-redirect" title="Unified EFI Forum">Unified EFI Forum</a>, an industry <a href="/wiki/Special_interest_group" title="Special interest group">special interest group</a>. EFI booting has been supported in only <a href="/wiki/Microsoft_Windows" title="Microsoft Windows">Microsoft Windows</a> versions supporting <a href="/wiki/GUID_Partition_Table" title="GUID Partition Table">GPT</a>,<sup id="cite_ref-windows-gpt_87-0" class="reference"><a href="#cite_note-windows-gpt-87"><span class="cite-bracket">[</span>85<span class="cite-bracket">]</span></a></sup> the <a href="/wiki/Linux_kernel" title="Linux kernel">Linux kernel</a> 2.6.1 and later, and <a href="/wiki/MacOS" title="MacOS">macOS</a> on <a href="/wiki/Apple%E2%80%93Intel_architecture" title="Apple–Intel architecture">Intel-based Macs</a>.<sup id="cite_ref-intel-uefi_88-0" class="reference"><a href="#cite_note-intel-uefi-88"><span class="cite-bracket">[</span>86<span class="cite-bracket">]</span></a></sup> As of 2014<sup class="plainlinks noexcerpt noprint asof-tag update" style="display:none;"><a class="external text" href="https://en.wikipedia.org/w/index.php?title=BIOS&action=edit">[update]</a></sup>, new PC hardware predominantly ships with UEFI firmware. The architecture of the rootkit safeguard can also prevent the system from running the user's own software changes, which makes UEFI controversial as a legacy BIOS replacement in the <a href="/wiki/Open_hardware" class="mw-redirect" title="Open hardware">open hardware</a> community. Also, <a href="/wiki/Windows_11" title="Windows 11">Windows 11</a> requires UEFI to boot,<sup id="cite_ref-89" class="reference"><a href="#cite_note-89"><span class="cite-bracket">[</span>87<span class="cite-bracket">]</span></a></sup> with the exception of IoT Enterprise editions of Windows 11.<sup id="cite_ref-11_IoT_req_11-1" class="reference"><a href="#cite_note-11_IoT_req-11"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> UEFI is required for devices shipping with Windows 8<sup id="cite_ref-90" class="reference"><a href="#cite_note-90"><span class="cite-bracket">[</span>88<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-91" class="reference"><a href="#cite_note-91"><span class="cite-bracket">[</span>89<span class="cite-bracket">]</span></a></sup> and above. </p><p>Other alternatives to the functionality of the "Legacy BIOS" in the x86 world include <a href="/wiki/Coreboot" title="Coreboot">coreboot</a> and <a href="/wiki/Libreboot" title="Libreboot">libreboot</a>. </p><p>Some servers and workstations use a platform-independent <a href="/wiki/Open_Firmware" title="Open Firmware">Open Firmware</a> (IEEE-1275) based on the <a href="/wiki/Forth_(programming_language)" title="Forth (programming language)">Forth</a> programming language; it is included with Sun's <a href="/wiki/SPARC" title="SPARC">SPARC</a> computers, IBM's <a href="/wiki/RS/6000" class="mw-redirect" title="RS/6000">RS/6000</a> line, and other <a href="/wiki/PowerPC" title="PowerPC">PowerPC</a> systems such as the <a href="/wiki/Common_Hardware_Reference_Platform" title="Common Hardware Reference Platform">CHRP</a> motherboards, along with the x86-based <a href="/wiki/OLPC_XO-1" class="mw-redirect" title="OLPC XO-1">OLPC XO-1</a>. </p><p>As of at least 2015, <a href="/wiki/Apple_Inc." title="Apple Inc.">Apple</a> has removed legacy BIOS support from the UEFI monitor in <a href="/wiki/Apple-Intel_architecture" class="mw-redirect" title="Apple-Intel architecture">Intel-based Macs</a>. As such, the BIOS utility no longer supports the legacy option, and prints "Legacy mode not supported on this system". </p><p>In 2017, Intel announced that it would remove legacy BIOS support by 2020. Since 2019, new Intel platform OEM PCs no longer support the legacy option.<sup id="cite_ref-92" class="reference"><a href="#cite_note-92"><span class="cite-bracket">[</span>90<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=25" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Double_boot" title="Double boot">Double boot</a></li> <li><a href="/wiki/Extended_System_Configuration_Data" title="Extended System Configuration Data">Extended System Configuration Data</a> (ESCD)</li> <li><a href="/wiki/Input/Output_Control_System" title="Input/Output Control System">Input/Output Control System</a></li> <li><a href="/wiki/ACPI" title="ACPI">ACPI</a> (Advanced Configuration and Power Interface)</li> <li><a href="/wiki/Ralf_Brown%27s_Interrupt_List" title="Ralf Brown's Interrupt List">Ralf Brown's Interrupt List</a> (RBIL) – interrupts, calls, interfaces, data structures, memory and port addresses, and processor opcodes for the x86 architecture</li> <li><a href="/wiki/System_Management_BIOS" title="System Management BIOS">System Management BIOS</a> (SMBIOS)</li> <li><a href="/wiki/UEFI" title="UEFI">UEFI</a> (Unified Extensible Firmware Interface)</li> <li><a href="/wiki/Das_U-Boot" title="Das U-Boot">Das U-Boot</a>, often used on embedded systems</li></ul> <div class="mw-heading mw-heading2"><h2 id="Notes">Notes</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=26" title="Edit section: Notes"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist reflist-lower-alpha"> <div class="mw-references-wrap"><ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text">Although the term BIOS predates 1981, the standard for <a href="/wiki/IBM_PC%E2%80%93compatible" title="IBM PC–compatible">IBM PC–compatible</a> computers started with the release of the original <a href="/wiki/IBM_Personal_Computer" title="IBM Personal Computer">IBM Personal Computer</a>.</span> </li> <li id="cite_note-30"><span class="mw-cite-backlink"><b><a href="#cite_ref-30">^</a></b></span> <span class="reference-text">The signature at offset <code>+0x1FE</code> in boot sectors is <code>0x55 0xAA</code>, that is <code>0x55</code> at offset <code>+0x1FE</code> and <code>0xAA</code> at offset <code>+0x1FF</code>. Since <a href="/wiki/Little-endian" class="mw-redirect" title="Little-endian">little-endian</a> representation must be assumed in the context of <a href="/wiki/IBM_PC%E2%80%93compatible" title="IBM PC–compatible">IBM PC–compatible</a> compatible, this can be written as 16-bit word <code>0xAA55</code> in programs for <a href="/wiki/Intel_x86" class="mw-redirect" title="Intel x86">x86</a> processors (note the swapped order), whereas it would have to be written as <code>0x55AA</code> in programs for other CPU architectures using a <a href="/wiki/Big-endian" class="mw-redirect" title="Big-endian">big-endian</a> representation. Since this has been mixed up numerous times in books and even in original Microsoft reference documents, this article uses the offset-based byte-wise on-disk representation to avoid any possible misinterpretation.</span> </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=27" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239543626"><div class="reflist reflist-columns references-column-width" style="column-width: 30em;"> <ol class="references"> <li id="cite_note-pcguidedefinition-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-pcguidedefinition_2-0">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20141221071646/http://www.pcguide.com/ref/mbsys/bios/index.htm">"Ref — System BIOS"</a>. <i>PCGuide</i>. Archived from <a rel="nofollow" class="external text" href="http://www.pcguide.com/ref/mbsys/bios/index.htm">the original</a> on 2014-12-21<span class="reference-accessdate">. Retrieved <span class="nowrap">2014-12-06</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=PCGuide&rft.atitle=Ref+%E2%80%94+System+BIOS&rft_id=http%3A%2F%2Fwww.pcguide.com%2Fref%2Fmbsys%2Fbios%2Findex.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></span> </li> <li id="cite_note-Kildall_1975_BDOS-3"><span class="mw-cite-backlink">^ <a href="#cite_ref-Kildall_1975_BDOS_3-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Kildall_1975_BDOS_3-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Kildall_1975_BDOS_3-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFKildall1975" class="citation cs2"><a href="/wiki/Gary_Kildall" title="Gary Kildall">Kildall, Gary Arlen</a> (June 1975), <i>CP/M 1.1 or 1.2 BIOS and BDOS for Lawrence Livermore Laboratories</i></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=CP%2FM+1.1+or+1.2+BIOS+and+BDOS+for+Lawrence+Livermore+Laboratories&rft.date=1975-06&rft.aulast=Kildall&rft.aufirst=Gary+Arlen&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></span> </li> <li id="cite_note-Kildall_1980_CPM-4"><span class="mw-cite-backlink">^ <a href="#cite_ref-Kildall_1980_CPM_4-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Kildall_1980_CPM_4-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Kildall_1980_CPM_4-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFKildall1980" class="citation web cs1"><a href="/wiki/Gary_Kildall" title="Gary Kildall">Kildall, Gary Arlen</a> (January 1980). <a rel="nofollow" class="external text" href="http://www.retrotechnology.com/dri/CPM_history_kildall.txt">"The History of CP/M - The Evolution of an Industry: One Person's Viewpoint"</a> (Vol. 5, No. 1, Number 41 ed.). <a href="/wiki/Dr._Dobb%27s_Journal" title="Dr. Dobb's Journal">Dr. Dobb's Journal</a> of Computer Calisthenics & Orthodontia. pp. 6–7. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20161124221907/http://www.retrotechnology.com/dri/CPM_history_kildall.txt">Archived</a> from the original on 2016-11-24<span class="reference-accessdate">. Retrieved <span class="nowrap">2013-06-03</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=The+History+of+CP%2FM+-+The+Evolution+of+an+Industry%3A+One+Person%27s+Viewpoint&rft.pages=6-7&rft.edition=Vol.+5%2C+No.+1%2C+Number+41&rft.pub=Dr.+Dobb%27s+Journal+of+Computer+Calisthenics+%26+Orthodontia&rft.date=1980-01&rft.aulast=Kildall&rft.aufirst=Gary+Arlen&rft_id=http%3A%2F%2Fwww.retrotechnology.com%2Fdri%2FCPM_history_kildall.txt&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></span> </li> <li id="cite_note-Booting_·_Linux_Inside-5"><span class="mw-cite-backlink">^ <a href="#cite_ref-Booting_·_Linux_Inside_5-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Booting_·_Linux_Inside_5-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://0xax.gitbooks.io/linux-insides/content/Booting/">"Booting · Linux Inside"</a>. <i>0xax.gitbooks.io</i><span class="reference-accessdate">. Retrieved <span class="nowrap">2020-11-10</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=0xax.gitbooks.io&rft.atitle=Booting+%C2%B7+Linux+Inside&rft_id=https%3A%2F%2F0xax.gitbooks.io%2Flinux-insides%2Fcontent%2FBooting%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></span> </li> <li id="cite_note-Bradley-6"><span class="mw-cite-backlink">^ <a href="#cite_ref-Bradley_6-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Bradley_6-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBradley" class="citation magazine cs1">Bradley, Tony. <a rel="nofollow" class="external text" href="http://www.pcworld.com/article/248426/r_i_p_bios_a_uefi_primer.html">"R.I.P. BIOS: A UEFI Primer"</a>. <i>PCWorld</i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20140127090326/http://www.pcworld.com/article/248426/r_i_p_bios_a_uefi_primer.html">Archived</a> from the original on 2014-01-27<span class="reference-accessdate">. Retrieved <span class="nowrap">2014-01-27</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=PCWorld&rft.atitle=R.I.P.+BIOS%3A+A+UEFI+Primer&rft.aulast=Bradley&rft.aufirst=Tony&rft_id=http%3A%2F%2Fwww.pcworld.com%2Farticle%2F248426%2Fr_i_p_bios_a_uefi_primer.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></span> </li> <li id="cite_note-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-7">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.intel.com/content/www/us/en/developer/articles/tool/unified-extensible-firmware-interface.html">"Unified Extensible Firmware Interface"</a>. <i>Intel</i>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Intel&rft.atitle=Unified+Extensible+Firmware+Interface&rft_id=https%3A%2F%2Fwww.intel.com%2Fcontent%2Fwww%2Fus%2Fen%2Fdeveloper%2Farticles%2Ftool%2Funified-extensible-firmware-interface.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></span> </li> <li id="cite_note-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-8">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="Legacy_bootloader_or_UEFI_application.3F" class="citation web cs1"><a rel="nofollow" class="external text" href="https://wiki.osdev.org/UEFI">"UEFI"</a>. <i>OSDev.org</i>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=OSDev.org&rft.atitle=UEFI&rft_id=https%3A%2F%2Fwiki.osdev.org%2FUEFI&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></span> </li> <li id="cite_note-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-9">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.intel.com/content/dam/doc/reference-guide/efi-compatibility-support-module-specification-v097.pdf">"Intel® Platform Innovation Framework for EFI Compatibility Support Module Specification (revision 0.97)"</a> <span class="cs1-format">(PDF)</span>. Intel. 2007-09-04<span class="reference-accessdate">. Retrieved <span class="nowrap">2013-10-06</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Intel%C2%AE+Platform+Innovation+Framework+for+EFI+Compatibility+Support+Module+Specification+%28revision+0.97%29&rft.pub=Intel&rft.date=2007-09-04&rft_id=http%3A%2F%2Fwww.intel.com%2Fcontent%2Fdam%2Fdoc%2Freference-guide%2Fefi-compatibility-support-module-specification-v097.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></span> </li> <li id="cite_note-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-10">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.intel.com/content/www/us/en/content-details/630266/removal-of-legacy-boot-support-for-intel-platforms-technical-advisory.html">"Removal of Legacy Boot Support for Intel Platforms Technical Advisory"</a><span class="reference-accessdate">. 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Intel. 1990. Section 10.2.3 First Instruction, p. 10-4<span class="reference-accessdate">. Retrieved <span class="nowrap">2013-11-03</span></span>. <q>Execution begins with the instruction addressed by the initial contents of the CS and IP registers. To allow the initialization software to be placed in a ROM at the top of the address space, the high 12 bits of addresses issued for the code segment are set, until the first instruction which loads the CS register, such as a far jump or call. As a result, instruction fetching begins from address 0FFFFFFF0H.</q></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=80386+Programmer%27s+Reference+Manual&rft.pages=Section+10.2.3+First+Instruction%2C+p.+10-4&rft.pub=Intel&rft.date=1990&rft_id=http%3A%2F%2Fbitsavers.org%2Fcomponents%2Fintel%2F80386%2F230985-003_386DX_Microprocessor_Programmers_Reference_Manual_1990.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></span> </li> <li id="cite_note-26"><span class="mw-cite-backlink"><b><a href="#cite_ref-26">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20120808162037/http://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-manual-325462.pdf">"Intel® 64 and IA-32 Architectures Software Developer's Manual"</a> <span class="cs1-format">(PDF)</span>. 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The EPROM containing the software-initialization code must be located at this address.</q></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Intel%C2%AE+64+and+IA-32+Architectures+Software+Developer%27s+Manual&rft.pages=Section+9.1.4+First+Instruction+Executed%2C+p.+2611&rft.pub=Intel&rft.date=2012-05&rft_id=http%3A%2F%2Fdownload.intel.com%2Fproducts%2Fprocessor%2Fmanual%2F325462.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></span> </li> <li id="cite_note-technical-ref-5-27-27"><span class="mw-cite-backlink"><b><a href="#cite_ref-technical-ref-5-27_27-0">^</a></b></span> <span class="reference-text">page 5-27 <i>IBM Personal Computer Hardware Reference Library Technical Reference</i>, 1984, publication number 6361459</span> </li> <li id="cite_note-28"><span class="mw-cite-backlink"><b><a href="#cite_ref-28">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.reenigne.org/crtc/PC-XT.pdf">"IBM 5162 PC XT286 TechRef 68X2537 Technical Reference manual"</a> <span class="cs1-format">(PDF)</span>. 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Springer. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-90-481-9431-5" title="Special:BookSources/978-90-481-9431-5"><bdi>978-90-481-9431-5</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Inside+NAND+Flash+Memories&rft.pub=Springer&rft.date=2010-07-27&rft.isbn=978-90-481-9431-5&rft.aulast=Micheloni&rft.aufirst=Rino&rft.au=Crippa%2C+Luca&rft.au=Marelli%2C+Alessia&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3Dvaq11vKwo_kC%26dq%3Dbios%2Bnor%2Bflash%26pg%3DPA2&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></span> </li> <li id="cite_note-59"><span class="mw-cite-backlink"><b><a href="#cite_ref-59">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMueller2004" class="citation book cs1">Mueller, Scott (2004). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=E1p2FDL7P5QC&dq=bios+cmos&pg=PA393"><i>Upgrading and Repairing PCS</i></a>. Que. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-7897-2974-3" title="Special:BookSources/978-0-7897-2974-3"><bdi>978-0-7897-2974-3</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Upgrading+and+Repairing+PCS&rft.pub=Que&rft.date=2004&rft.isbn=978-0-7897-2974-3&rft.aulast=Mueller&rft.aufirst=Scott&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DE1p2FDL7P5QC%26dq%3Dbios%2Bcmos%26pg%3DPA393&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></span> </li> <li id="cite_note-60"><span class="mw-cite-backlink"><b><a href="#cite_ref-60">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFClarkeTetz2007" class="citation book cs1">Clarke, Glen E.; Tetz, Edward (2007-01-30). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=V48MZCwICH8C&dq=bios+eeprom&pg=PA180"><i>CompTIA A+ Certification All-In-One Desk Reference for Dummies</i></a>. John Wiley & Sons. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-471-74811-3" title="Special:BookSources/978-0-471-74811-3"><bdi>978-0-471-74811-3</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=CompTIA+A%2B+Certification+All-In-One+Desk+Reference+for+Dummies&rft.pub=John+Wiley+%26+Sons&rft.date=2007-01-30&rft.isbn=978-0-471-74811-3&rft.aulast=Clarke&rft.aufirst=Glen+E.&rft.au=Tetz%2C+Edward&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DV48MZCwICH8C%26dq%3Dbios%2Beeprom%26pg%3DPA180&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></span> </li> <li id="cite_note-smart-computing-97-61"><span class="mw-cite-backlink"><b><a href="#cite_ref-smart-computing-97_61-0">^</a></b></span> <span class="reference-text">"<a rel="nofollow" class="external text" href="http://www.smartcomputing.com/editorial/article.asp?article=articles%2F1997%2Fjun97%2F060997%2F060997.asp">Decoding RAM & ROM</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20120406173605/http://www.smartcomputing.com/editorial/article.asp?article=articles%2F1997%2Fjun97%2F060997%2F060997.asp">Archived</a> 2012-04-06 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a>." <i><a href="/wiki/Smart_Computing" class="mw-redirect" title="Smart Computing">Smart Computing</a></i>. June 1997. Volume 8, Issue 6.</span> </li> <li id="cite_note-smart-computing-96-62"><span class="mw-cite-backlink"><b><a href="#cite_ref-smart-computing-96_62-0">^</a></b></span> <span class="reference-text">"<a rel="nofollow" class="external text" href="http://www.smartcomputing.com/editorial/article.asp?article=articles%2F1996%2Fmar96%2F96n0324%2F96n0324.asp">Upgrading Your Flash BIOS For Plug And Play</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20120406173635/http://www.smartcomputing.com/editorial/article.asp?article=articles%2F1996%2Fmar96%2F96n0324%2F96n0324.asp">Archived</a> 2012-04-06 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a>." <i><a href="/wiki/Smart_Computing" class="mw-redirect" title="Smart Computing">Smart Computing</a></i>. March 1996. Volume 7, Issue 3.</span> </li> <li id="cite_note-smart-somputing-99-63"><span class="mw-cite-backlink"><b><a href="#cite_ref-smart-somputing-99_63-0">^</a></b></span> <span class="reference-text">"<a rel="nofollow" class="external text" href="http://www.smartcomputing.com/editorial/article.asp?article=articles/archive/g0704/41u6/41u6.asp&guid=">Time To Check BIOS</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20110716092732/http://www.smartcomputing.com/editorial/article.asp?article=articles%2Farchive%2Fg0704%2F41u6%2F41u6.asp&guid=">Archived</a> 2011-07-16 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a>." <i><a href="/wiki/Smart_Computing" class="mw-redirect" title="Smart Computing">Smart Computing</a></i>. April 1999. Volume 7, Issue 4.</span> </li> <li id="cite_note-64"><span class="mw-cite-backlink"><b><a href="#cite_ref-64">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20210818182418/https://images.slideplayer.com/26/8671671/slides/slide_5.jpg">"Archived copy"</a>. Archived from <a rel="nofollow" class="external text" href="https://images.slideplayer.com/26/8671671/slides/slide_5.jpg">the original</a> on 2021-08-18<span class="reference-accessdate">. Retrieved <span class="nowrap">2021-04-01</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Archived+copy&rft_id=https%3A%2F%2Fimages.slideplayer.com%2F26%2F8671671%2Fslides%2Fslide_5.jpg&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span><span class="cs1-maint citation-comment"><code class="cs1-code">{{<a href="/wiki/Template:Cite_web" title="Template:Cite web">cite web</a>}}</code>: CS1 maint: archived copy as title (<a href="/wiki/Category:CS1_maint:_archived_copy_as_title" title="Category:CS1 maint: archived copy as title">link</a>)</span></span> </li> <li id="cite_note-geek-splashtop-65"><span class="mw-cite-backlink"><b><a href="#cite_ref-geek-splashtop_65-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20080907134251/http://www.geek.com/splashtops-instant-on-linux-desktop/">"SplashTop's Instant-On Linux Desktop | Geek.com"</a>. 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Retrieved <span class="nowrap">2013-02-02</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=2007-11-27&rft.atitle=The+life+and+times+of+the+modern+motherboard&rft.au=Posted+by+Alex+Watson%2C+possibly+repost+from+original+content+on+custompc.com+%5Bunclear%5D&rft_id=http%3A%2F%2Fwww.bit-tech.net%2Fcustompc%2Ffeatures%2F601716%2Fthe-life-and-times-of-the-modern-motherboard%2Fpage1.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></span> </li> <li id="cite_note-Hilber-67"><span class="mw-cite-backlink"><b><a href="#cite_ref-Hilber_67-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFDavid_Hilber_Jr.2009" class="citation web cs1">David Hilber Jr. (August 2009). <a rel="nofollow" class="external text" href="http://download.intel.com/embedded/processor/whitepaper/322506.pdf">"Considerations for Designing an Embedded Intel Architecture System with System Memory Down"</a> <span class="cs1-format">(PDF)</span>. <a href="/wiki/Intel" title="Intel">Intel</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20121018185412/http://download.intel.com/embedded/processor/whitepaper/322506.pdf">Archived</a> <span class="cs1-format">(PDF)</span> from the original on 2012-10-18<span class="reference-accessdate">. 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Retrieved <span class="nowrap">2015-12-06</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Award+BIOS+logo&rft.date=2015-06-15&rft_id=http%3A%2F%2Ffileformats.archiveteam.org%2Fwiki%2FAward_BIOS_logo&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></span> </li> <li id="cite_note-71"><span class="mw-cite-backlink"><b><a href="#cite_ref-71">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://books.google.com/books?id=zzAEAAAAMBAJ&pg=PA8">Phoenix Eagerly Waiting to Clone Next-Generation IBM BIOS</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20140122080016/http://books.google.com/books?id=zzAEAAAAMBAJ&pg=PA8">Archived</a> 2014-01-22 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a>, <i>InfoWorld</i>, 9 March 1987.</span> </li> <li id="cite_note-72"><span class="mw-cite-backlink"><b><a href="#cite_ref-72">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation book cs1"><a rel="nofollow" class="external text" href="https://ieeexplore.ieee.org/document/763383"><i>IEEE Standard for Boot (Initialization Configuration) Firmware: Core Requirements and Practices</i></a>. 1994-10-28. pp. 1–262. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1109%2FIEEESTD.1994.89427">10.1109/IEEESTD.1994.89427</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-7381-1194-0" title="Special:BookSources/978-0-7381-1194-0"><bdi>978-0-7381-1194-0</bdi></a>. 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Archived from <a rel="nofollow" class="external text" href="http://threatpost.com/en_us/blogs/researchers-unveil-persistent-bios-attack-methods-031909">the original</a> on 2010-01-30<span class="reference-accessdate">. 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Retrieved <span class="nowrap">2011-09-19</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=blog&rft.atitle=Mebromi%3A+the+first+BIOS+rootkit+in+the+wild&rft.date=2011-09-13&rft.aulast=Giuliani&rft.aufirst=Marco&rft_id=http%3A%2F%2Fblog.webroot.com%2F2011%2F09%2F13%2Fmebromi-the-first-bios-rootkit-in-the-wild%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></span> </li> <li id="cite_note-BMW-80"><span class="mw-cite-backlink"><b><a href="#cite_ref-BMW_80-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20110925051031/http://bbs.360.cn/4005462/251096134.html">"360发布"BMW病毒"技术分析报告"</a>. <i><a href="/wiki/Blog" title="Blog">blog</a></i>. 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Retrieved <span class="nowrap">2011-09-19</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=blog&rft.atitle=360%E5%8F%91%E5%B8%83%22BMW%E7%97%85%E6%AF%92%22%E6%8A%80%E6%9C%AF%E5%88%86%E6%9E%90%E6%8A%A5%E5%91%8A&rft_id=http%3A%2F%2Fbbs.360.cn%2F4005462%2F251096134.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></span> </li> <li id="cite_note-Yuan-81"><span class="mw-cite-backlink"><b><a href="#cite_ref-Yuan_81-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFYuan" class="citation web cs1">Yuan, Liang. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20110923145036/http://www.symantec.com/security_response/writeup.jsp?docid=2011-090609-4557-99">"Trojan.Mebromi"</a>. <i><a href="/w/index.php?title=Threat_Response&action=edit&redlink=1" class="new" title="Threat Response (page does not exist)">Threat Response</a></i>. Archived from <a rel="nofollow" class="external text" href="http://www.symantec.com/security_response/writeup.jsp?docid=2011-090609-4557-99">the original</a> on 2011-09-23<span class="reference-accessdate">. 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Retrieved <span class="nowrap">2019-03-26</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=The+Register&rft.atitle=NSA+alleges+%27BIOS+plot+to+destroy+PCs%27&rft.date=2013-12-16&rft.aulast=Sharwood&rft.aufirst=Simon&rft_id=https%3A%2F%2Fwww.theregister.co.uk%2F2013%2F12%2F16%2Fnsa_alleges_bios_plot_to_destroy_pcs%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></span> </li> <li id="cite_note-windows-gpt-87"><span class="mw-cite-backlink"><b><a href="#cite_ref-windows-gpt_87-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.microsoft.com/whdc/device/storage/gpt_faq.mspx">"Windows and GPT FAQ"</a>. <i>microsoft.com</i>. Microsoft. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20110219111649/http://www.microsoft.com/whdc/device/storage/GPT_FAQ.mspx">Archived</a> from the original on 2011-02-19<span class="reference-accessdate">. Retrieved <span class="nowrap">2014-12-06</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=microsoft.com&rft.atitle=Windows+and+GPT+FAQ&rft_id=http%3A%2F%2Fwww.microsoft.com%2Fwhdc%2Fdevice%2Fstorage%2Fgpt_faq.mspx&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></span> </li> <li id="cite_note-intel-uefi-88"><span class="mw-cite-backlink"><b><a href="#cite_ref-intel-uefi_88-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.intel.com/technology/efi/">"Extensible Firmware Interface (EFI) and Unified EFI (UEFI)"</a>. <i>Intel</i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20100105051711/http://www.intel.com/technology/efi/">Archived</a> from the original on 2010-01-05<span class="reference-accessdate">. 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Retrieved <span class="nowrap">2021-10-14</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Windows+11+Specs+and+System+Requirements+%26%23124%3B+Microsoft&rft.pub=Microsoft&rft_id=https%3A%2F%2Fwww.microsoft.com%2Fen-us%2Fwindows%2Fwindows-11-specifications&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></span> </li> <li id="cite_note-90"><span class="mw-cite-backlink"><b><a href="#cite_ref-90">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.networkworld.com/article/738394/microsoft-subnet-next-gen-boot-spec-could-forever-lock-linux-off-windows-8-pcs.html">"Next-gen boot spec could forever lock Linux off Windows 8 PCS"</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Next-gen+boot+spec+could+forever+lock+Linux+off+Windows+8+PCS&rft_id=https%3A%2F%2Fwww.networkworld.com%2Farticle%2F738394%2Fmicrosoft-subnet-next-gen-boot-spec-could-forever-lock-linux-off-windows-8-pcs.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></span> </li> <li id="cite_note-91"><span class="mw-cite-backlink"><b><a href="#cite_ref-91">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://arstechnica.com/information-technology/2011/09/windows-8-secure-boot-will-complicate-linux-installs/">"Windows 8 secure boot could complicate Linux installs"</a>. 2011-09-21.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Windows+8+secure+boot+could+complicate+Linux+installs&rft.date=2011-09-21&rft_id=https%3A%2F%2Farstechnica.com%2Finformation-technology%2F2011%2F09%2Fwindows-8-secure-boot-will-complicate-linux-installs%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></span> </li> <li id="cite_note-92"><span class="mw-cite-backlink"><b><a href="#cite_ref-92">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFTung2017" class="citation web cs1">Tung, Liam (2017-11-20). <a rel="nofollow" class="external text" href="https://www.zdnet.com/article/intel-were-ending-all-legacy-bios-support-by-2020/">"Intel: We're ending all legacy BIOS support by 2020"</a>. <i><a href="/wiki/ZDNET" title="ZDNET">ZDNET</a></i>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=ZDNET&rft.atitle=Intel%3A+We%27re+ending+all+legacy+BIOS+support+by+2020&rft.date=2017-11-20&rft.aulast=Tung&rft.aufirst=Liam&rft_id=https%3A%2F%2Fwww.zdnet.com%2Farticle%2Fintel-were-ending-all-legacy-bios-support-by-2020%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></span> </li> </ol></div> <div class="mw-heading mw-heading2"><h2 id="Further_reading">Further reading</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=28" title="Edit section: Further reading"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation book cs1"><i>IBM Personal Computer Technical Reference</i> (Revised ed.). <a href="/wiki/IBM_Corporation" class="mw-redirect" title="IBM Corporation">IBM Corporation</a>. March 1983.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=IBM+Personal+Computer+Technical+Reference&rft.edition=Revised&rft.pub=IBM+Corporation&rft.date=1983-03&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation book cs1 cs1-prop-long-vol"><i>IBM Personal Computer AT Technical Reference</i>. IBM Personal Computer Hardware Reference Library. Vol. 0, 1, 2 (Revised ed.). <a href="/wiki/IBM_Corporation" class="mw-redirect" title="IBM Corporation">IBM Corporation</a>. March 1986 [1984-03]. 1502494, 6139362, 6183310, 6183312, 6183355, 6280070, 6280099.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=IBM+Personal+Computer+AT+Technical+Reference&rft.series=IBM+Personal+Computer+Hardware+Reference+Library&rft.edition=Revised&rft.pub=IBM+Corporation&rft.date=1986-03&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFPhoenix_Technologies,_Ltd.1989" class="citation book cs1"><a href="/wiki/Phoenix_Technologies" title="Phoenix Technologies">Phoenix Technologies, Ltd.</a> (1989) [1987]. <a rel="nofollow" class="external text" href="https://archive.org/details/System_BIOS_for_IBM_PC_XT_AT_Computers_and_Compatibles"><i>System BIOS for IBM PC/XT/AT Computers and Compatibles — The Complete Guide to ROM-Based System Software</i></a>. Phoenix Technical Reference Series (1st ed.). <a href="/wiki/Addison_Wesley_Publishing_Company,_Inc." class="mw-redirect" title="Addison Wesley Publishing Company, Inc.">Addison Wesley Publishing Company, Inc.</a> <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-201-51806-6" title="Special:BookSources/0-201-51806-6"><bdi>0-201-51806-6</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=System+BIOS+for+IBM+PC%2FXT%2FAT+Computers+and+Compatibles+%E2%80%94+The+Complete+Guide+to+ROM-Based+System+Software&rft.series=Phoenix+Technical+Reference+Series&rft.edition=1st&rft.pub=Addison+Wesley+Publishing+Company%2C+Inc.&rft.date=1989&rft.isbn=0-201-51806-6&rft.au=Phoenix+Technologies%2C+Ltd.&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2FSystem_BIOS_for_IBM_PC_XT_AT_Computers_and_Compatibles&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFPhoenix_Technologies,_Ltd.1989" class="citation book cs1"><a href="/wiki/Phoenix_Technologies" title="Phoenix Technologies">Phoenix Technologies, Ltd.</a> (1989) [1987]. <i>CBIOS for IBM PS/2 Computers and Compatibles — The Complete Guide to ROM-Based System Software for DOS</i>. Phoenix Technical Reference Series (1st ed.). <a href="/wiki/Addison_Wesley_Publishing_Company,_Inc." class="mw-redirect" title="Addison Wesley Publishing Company, Inc.">Addison Wesley Publishing Company, Inc.</a> <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-201-51804-X" title="Special:BookSources/0-201-51804-X"><bdi>0-201-51804-X</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=CBIOS+for+IBM+PS%2F2+Computers+and+Compatibles+%E2%80%94+The+Complete+Guide+to+ROM-Based+System+Software+for+DOS&rft.series=Phoenix+Technical+Reference+Series&rft.edition=1st&rft.pub=Addison+Wesley+Publishing+Company%2C+Inc.&rft.date=1989&rft.isbn=0-201-51804-X&rft.au=Phoenix+Technologies%2C+Ltd.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFPhoenix_Technologies,_Ltd.1989" class="citation book cs1"><a href="/wiki/Phoenix_Technologies" title="Phoenix Technologies">Phoenix Technologies, Ltd.</a> (1989) [1987]. <i>ABIOS for IBM PS/2 Computers and Compatibles — The Complete Guide to ROM-Based System Software for OS/2</i>. Phoenix Technical Reference Series (1st ed.). <a href="/wiki/Addison_Wesley_Publishing_Company,_Inc." class="mw-redirect" title="Addison Wesley Publishing Company, Inc.">Addison Wesley Publishing Company, Inc.</a> <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-201-51805-8" title="Special:BookSources/0-201-51805-8"><bdi>0-201-51805-8</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=ABIOS+for+IBM+PS%2F2+Computers+and+Compatibles+%E2%80%94+The+Complete+Guide+to+ROM-Based+System+Software+for+OS%2F2&rft.series=Phoenix+Technical+Reference+Series&rft.edition=1st&rft.pub=Addison+Wesley+Publishing+Company%2C+Inc.&rft.date=1989&rft.isbn=0-201-51805-8&rft.au=Phoenix+Technologies%2C+Ltd.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFPhoenix_Technologies,_Ltd.1991" class="citation book cs1"><a href="/wiki/Phoenix_Technologies" title="Phoenix Technologies">Phoenix Technologies, Ltd.</a> (June 1991). <span class="id-lock-registration" title="Free registration required"><a rel="nofollow" class="external text" href="https://archive.org/details/isbn_9780201577600"><i>System BIOS for IBM PCs, Compatibles, and EISA Computers — The Complete Guide to ROM-Based System Software</i></a></span>. Phoenix Technical Reference Series (2nd ed.). Amsterdam: <a href="/wiki/Addison_Wesley_Publishing_Company,_Inc." class="mw-redirect" title="Addison Wesley Publishing Company, Inc.">Addison Wesley Publishing Company, Inc.</a> <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-201-57760-7" title="Special:BookSources/0-201-57760-7"><bdi>0-201-57760-7</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=System+BIOS+for+IBM+PCs%2C+Compatibles%2C+and+EISA+Computers+%E2%80%94+The+Complete+Guide+to+ROM-Based+System+Software&rft.place=Amsterdam&rft.series=Phoenix+Technical+Reference+Series&rft.edition=2nd&rft.pub=Addison+Wesley+Publishing+Company%2C+Inc.&rft.date=1991-06&rft.isbn=0-201-57760-7&rft.au=Phoenix+Technologies%2C+Ltd.&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fisbn_9780201577600&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></li> <li><a rel="nofollow" class="external text" href="http://bioshacking.blogspot.com/2012/02/bios-disassembly-ninjutsu-uncovered-1st.html">BIOS Disassembly Ninjutsu Uncovered, 1st edition</a>, a freely available book in PDF format <a rel="nofollow" class="external autonumber" href="https://web.archive.org/web/20220402165916/http://www.lejabeach.com/sisubb/BIOS_Disassembly_Ninjutsu_Uncovered.pdf">[1]</a></li> <li><a rel="nofollow" class="external text" href="http://osxbook.com/book/bonus/chapter4/firmware/">More Power To Firmware</a>, free bonus chapter to the <i>Mac OS X Internals: A Systems Approach</i> book</li></ul> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=BIOS&action=edit&section=29" title="Edit section: External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1235681985">.mw-parser-output .side-box{margin:4px 0;box-sizing:border-box;border:1px solid #aaa;font-size:88%;line-height:1.25em;background-color:var(--background-color-interactive-subtle,#f8f9fa);display:flow-root}.mw-parser-output .side-box-abovebelow,.mw-parser-output .side-box-text{padding:0.25em 0.9em}.mw-parser-output .side-box-image{padding:2px 0 2px 0.9em;text-align:center}.mw-parser-output .side-box-imageright{padding:2px 0.9em 2px 0;text-align:center}@media(min-width:500px){.mw-parser-output .side-box-flex{display:flex;align-items:center}.mw-parser-output .side-box-text{flex:1;min-width:0}}@media(min-width:720px){.mw-parser-output .side-box{width:238px}.mw-parser-output .side-box-right{clear:right;float:right;margin-left:1em}.mw-parser-output .side-box-left{margin-right:1em}}</style><style data-mw-deduplicate="TemplateStyles:r1237033735">@media print{body.ns-0 .mw-parser-output .sistersitebox{display:none!important}}@media screen{html.skin-theme-clientpref-night .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-en-v2.svg"]{background-color:white}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-en-v2.svg"]{background-color:white}}</style><div class="side-box side-box-right plainlinks sistersitebox"><style data-mw-deduplicate="TemplateStyles:r1126788409">.mw-parser-output .plainlist ol,.mw-parser-output .plainlist ul{line-height:inherit;list-style:none;margin:0;padding:0}.mw-parser-output .plainlist ol li,.mw-parser-output .plainlist ul li{margin-bottom:0}</style> <div class="side-box-flex"> <div class="side-box-image"><span class="noviewer" typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/30px-Commons-logo.svg.png" decoding="async" width="30" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/45px-Commons-logo.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/59px-Commons-logo.svg.png 2x" data-file-width="1024" data-file-height="1376" /></span></span></div> <div class="side-box-text plainlist">Wikimedia Commons has media related to <span style="font-weight: bold; font-style: italic;"><a href="https://commons.wikimedia.org/wiki/Category:Basic_Input_Output_System" class="extiw" title="commons:Category:Basic Input Output System">the BIOS</a></span>.</div></div> </div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1235681985"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1237033735"><div class="side-box side-box-right plainlinks sistersitebox"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1126788409"> <div class="side-box-flex"> <div class="side-box-image"><span class="noviewer" typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/40px-Wiktionary-logo-en-v2.svg.png" decoding="async" width="40" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/60px-Wiktionary-logo-en-v2.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/80px-Wiktionary-logo-en-v2.svg.png 2x" data-file-width="512" data-file-height="512" /></span></span></div> <div class="side-box-text plainlist">Look up <i><b><a href="https://en.wiktionary.org/wiki/BIOS" class="extiw" title="wiktionary:BIOS">BIOS</a></b></i> in Wiktionary, the free dictionary.</div></div> </div> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20110715081320/http://www.phoenix.com/resources/specs-bbs101.pdf">"BIOS Boot Specification 1.01"</a> <span class="cs1-format">(PDF)</span>. <i>Phoenix.com</i>. 1996-01-11. Archived from <a rel="nofollow" class="external text" href="http://www.phoenix.com/resources/specs-bbs101.pdf">the original</a> <span class="cs1-format">(PDF)</span> on 2011-07-15.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Phoenix.com&rft.atitle=BIOS+Boot+Specification+1.01&rft.date=1996-01-11&rft_id=http%3A%2F%2Fwww.phoenix.com%2Fresources%2Fspecs-bbs101.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://computer.howstuffworks.com/bios.htm">"How BIOS Works"</a>. <i>How Stuff Works</i>. 2000-09-06.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=How+Stuff+Works&rft.atitle=How+BIOS+Works&rft.date=2000-09-06&rft_id=http%3A%2F%2Fcomputer.howstuffworks.com%2Fbios.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20071128165740/http://download.intel.com/design/flcomp/support/applnots/29216101.pdf">"Implementing a Plug and Play BIOS Using Intel's Boot Block Flash Memory"</a> <span class="cs1-format">(PDF)</span>. <i>Intel</i>. February 1995. Archived from <a rel="nofollow" class="external text" href="http://download.intel.com/design/flcomp/support/applnots/29216101.pdf">the original</a> <span class="cs1-format">(PDF)</span> on 2007-11-28<span class="reference-accessdate">. Retrieved <span class="nowrap">2007-11-28</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Intel&rft.atitle=Implementing+a+Plug+and+Play+BIOS+Using+Intel%27s+Boot+Block+Flash+Memory&rft.date=1995-02&rft_id=http%3A%2F%2Fdownload.intel.com%2Fdesign%2Fflcomp%2Fsupport%2Fapplnots%2F29216101.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20140127174941/http://www.techarp.com/freebog.aspx">"List of BIOS options"</a>. <i>techarp.com</i>. Archived from <a rel="nofollow" class="external text" href="http://www.techarp.com/freebog.aspx">the original</a> on 2014-01-27.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=techarp.com&rft.atitle=List+of+BIOS+options&rft_id=http%3A%2F%2Fwww.techarp.com%2Ffreebog.aspx&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation news cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20110430213042/http://www.phrack.com/archives/66/p66_0x07_Persistent%20BIOS%20infection_by_aLS%20and%20Alfredo.txt">"Persistent BIOS Infection"</a>. <i><a href="/wiki/Phrack" title="Phrack">Phrack</a></i>. No. 66. 2009-06-01. Archived from <a rel="nofollow" class="external text" href="http://www.phrack.com/archives/66/p66_0x07_Persistent%20BIOS%20infection_by_aLS%20and%20Alfredo.txt">the original</a> on 2011-04-30<span class="reference-accessdate">. Retrieved <span class="nowrap">2011-04-30</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Phrack&rft.atitle=Persistent+BIOS+Infection&rft.issue=66&rft.date=2009-06-01&rft_id=http%3A%2F%2Fwww.phrack.com%2Farchives%2F66%2Fp66_0x07_Persistent%2520BIOS%2520infection_by_aLS%2520and%2520Alfredo.txt&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABIOS" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20070329124418/http://download.intel.com/design/flcomp/applnots/29219202.PDF">"Preventing BIOS Failures Using Intel Boot Block Flash Memory"</a> <span class="cs1-format">(PDF)</span>. <i><a href="/wiki/Intel" title="Intel">Intel</a></i>. December 1998. Archived from <a rel="nofollow" class="external text" href="http://download.intel.com/design/flcomp/applnots/29219202.PDF">the original</a> <span class="cs1-format">(PDF)</span> on 2007-03-29<span class="reference-accessdate">. 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class="nv-edit"><a href="/wiki/Special:EditPage/Template:Firmware_and_booting" title="Special:EditPage/Template:Firmware and booting"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Firmware_and_booting" style="font-size:114%;margin:0 4em"><a href="/wiki/Firmware" title="Firmware">Firmware</a> and <a href="/wiki/Booting" title="Booting">booting</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Processes</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><span class="nowrap"><a href="/wiki/Booting_process_of_Windows" title="Booting process of Windows">Windows</a></span> <ul><li><span class="nowrap"><a href="/wiki/Architecture_of_Windows_9x#Boot_sequence" title="Architecture of Windows 9x">9x</a></span></li> <li><span class="nowrap"><a href="/wiki/Booting_process_of_Windows_NT" class="mw-redirect" title="Booting process of Windows NT">NT</a></span></li></ul></li> <li><span class="nowrap"><a href="/wiki/Booting_process_of_Linux" title="Booting process of Linux">Linux</a></span> <ul><li><span class="nowrap"><a href="/wiki/Booting_process_of_Android_devices" title="Booting process of Android devices">Android</a></span></li></ul></li></ul> </div></td><td class="noviewer navbox-image" rowspan="10" style="width:1px;padding:0 0 0 2px"><div><span typeof="mw:File"><a href="/wiki/File:WD_Blue_WD5000LPVX_-_controller_-_Winbond_25X20CLVIG-0182.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/f/f8/WD_Blue_WD5000LPVX_-_controller_-_Winbond_25X20CLVIG-0182.jpg/100px-WD_Blue_WD5000LPVX_-_controller_-_Winbond_25X20CLVIG-0182.jpg" decoding="async" width="100" height="100" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/f8/WD_Blue_WD5000LPVX_-_controller_-_Winbond_25X20CLVIG-0182.jpg/150px-WD_Blue_WD5000LPVX_-_controller_-_Winbond_25X20CLVIG-0182.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/f8/WD_Blue_WD5000LPVX_-_controller_-_Winbond_25X20CLVIG-0182.jpg/200px-WD_Blue_WD5000LPVX_-_controller_-_Winbond_25X20CLVIG-0182.jpg 2x" data-file-width="1535" data-file-height="1535" /></a></span></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Booting <a href="/wiki/Firmware#Computers" title="Firmware">firmware</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Types</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><span class="nowrap"><a href="/wiki/Proprietary_firmware" title="Proprietary firmware">Proprietary firmware</a></span></li> <li><span class="nowrap"><a href="/wiki/Open-source_firmware" title="Open-source firmware">Open-source firmware</a></span></li> <li><span class="nowrap"><a href="/wiki/Custom_firmware" title="Custom firmware">Custom firmware</a></span></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Interfaces</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><span class="nowrap"><a href="/wiki/UEFI" title="UEFI">UEFI</a></span></li> <li><span class="nowrap"><a class="mw-selflink selflink">BIOS</a></span> <ul><li><span class="nowrap"><a href="/wiki/Video_BIOS" title="Video BIOS">Video BIOS</a></span></li></ul></li> <li><span class="nowrap"><a href="/wiki/Open_Firmware" title="Open Firmware">Open Firmware</a></span></li> <li><span class="nowrap"><a href="/wiki/ACPI" title="ACPI">ACPI</a></span></li> <li><span class="nowrap"><a href="/wiki/MultiProcessor_Specification" title="MultiProcessor Specification">MultiProcessor Specification</a></span></li> <li><span class="nowrap"><a href="/wiki/Advanced_Power_Management" title="Advanced Power Management">APM</a></span></li> <li><span class="nowrap"><a href="/wiki/Legacy_Plug_and_Play" title="Legacy Plug and Play">Legacy Plug and Play</a></span></li> <li><span class="nowrap"><a href="/wiki/ARC_(specification)" title="ARC (specification)">AlphaBIOS</a></span></li> <li><span class="nowrap"><a href="/wiki/SRM_firmware" title="SRM firmware">SRM</a></span></li> <li><span class="nowrap"><a href="/wiki/Simple_Firmware_Interface" title="Simple Firmware Interface">SFI</a></span></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Implementations</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><span class="nowrap"><a href="/wiki/SeaBIOS" title="SeaBIOS">SeaBIOS</a></span></li> <li><span class="nowrap"><a href="/wiki/Award_Software" title="Award Software">Award BIOS</a></span></li> <li><span class="nowrap"><a href="/wiki/American_Megatrends" title="American Megatrends">American Megatrends</a></span> <ul><li><span class="nowrap"><a href="/wiki/AMIBIOS" class="mw-redirect" title="AMIBIOS">AMIBIOS</a></span></li> <li><span class="nowrap"><a href="/wiki/AMI_Aptio" class="mw-redirect" title="AMI Aptio">AMI Aptio</a></span></li></ul></li> <li><span class="nowrap"><a href="/wiki/Insyde_Software" title="Insyde Software">InsydeH2O</a></span></li> <li><span class="nowrap"><a href="/wiki/Phoenix_Technologies" title="Phoenix Technologies">Phoenix SecureCore UEFI</a></span></li> <li><span class="nowrap"><a href="/wiki/TianoCore_EDK_II" title="TianoCore EDK II">TianoCore EDK II</a></span></li> <li><span class="nowrap"><a href="/wiki/OpenBIOS" title="OpenBIOS">OpenBIOS</a></span></li> <li><span class="nowrap"><a href="/wiki/Coreboot" title="Coreboot">Coreboot</a></span></li> <li><span class="nowrap"><a href="/wiki/Libreboot" title="Libreboot">Libreboot</a></span></li> <li><span class="nowrap"><a href="/wiki/LinuxBoot" title="LinuxBoot">LinuxBoot</a></span></li> <li><span class="nowrap"><a href="/wiki/Kickstart_(Amiga)" title="Kickstart (Amiga)">Kickstart</a></span></li> <li><span class="nowrap"><a href="/wiki/Run-Time_Abstraction_Services" title="Run-Time Abstraction Services">Run-Time Abstraction Services</a></span></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Hybrid firmware bootloader</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><span class="nowrap"><a href="/wiki/Common_Firmware_Environment" title="Common Firmware Environment">Common Firmware Environment</a> </span></li> <li><span class="nowrap"><a href="/wiki/Das_U-Boot" title="Das U-Boot">Das U-Boot</a></span></li> <li><span class="nowrap"><a href="/wiki/ARCS_(computing)" title="ARCS (computing)">ARCS</a></span></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Bootloaders" class="mw-redirect" title="Bootloaders">Bootloaders</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><span class="nowrap"><a href="/wiki/Bootloader_unlocking" title="Bootloader unlocking">Bootloader unlocking</a></span></li> <li><span class="nowrap"><a href="/wiki/Comparison_of_bootloaders" title="Comparison of bootloaders">Comparison of bootloaders</a></span></li></ul> </div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th id="Implementations" scope="row" class="navbox-group" style="width:1%">Implementations</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><span class="nowrap"><a href="/wiki/Acronis_OS_Selector" class="mw-redirect" title="Acronis OS Selector">Acronis OS Selector</a></span></li> <li><span class="nowrap"><a href="/wiki/Barebox" title="Barebox">Barebox</a></span></li> <li><span class="nowrap"><a href="/wiki/BootManager" class="mw-redirect" title="BootManager">BootManager</a></span></li> <li><span class="nowrap"><a href="/wiki/BootX_(Apple)" title="BootX (Apple)">BootX (Apple)</a></span></li> <li><span class="nowrap"><a href="/wiki/BootX_(Linux)" title="BootX (Linux)">BootX (Linux)</a></span></li> <li><span class="nowrap"><a href="/wiki/GNU_GRUB" title="GNU GRUB">GNU GRUB</a></span></li> <li><span class="nowrap"><a href="/wiki/IBoot" title="IBoot">iBoot</a></span></li> <li><span class="nowrap"><a href="/wiki/Systemd-boot" title="Systemd-boot">systemd-boot</a></span></li> <li><span class="nowrap"><a href="/wiki/Loadlin" title="Loadlin">loadlin</a></span></li> <li><span class="nowrap"><a href="/wiki/NTLDR" title="NTLDR">NTLDR</a></span></li> <li><span class="nowrap"><a href="/wiki/OpeniBoot" title="OpeniBoot">OpeniBoot</a></span></li> <li><span class="nowrap"><a href="/wiki/RedBoot" title="RedBoot">RedBoot</a></span></li> <li><span class="nowrap"><a href="/wiki/REFInd" title="REFInd">rEFInd</a></span></li> <li><span class="nowrap"><a href="/wiki/REFIt" title="REFIt">rEFIt</a></span></li> <li><span class="nowrap"><a href="/wiki/SYSLINUX" title="SYSLINUX">SYSLINUX</a></span></li> <li><span class="nowrap"><a href="/wiki/Windows_Boot_Manager" title="Windows Boot Manager">Windows Boot Manager</a></span></li> <li><span class="nowrap"><a href="/wiki/XOSL" title="XOSL">xOSL</a></span></li> <li><span class="nowrap"><a href="/wiki/Yaboot" title="Yaboot">Yaboot</a></span></li> <li><span class="nowrap"><a href="/wiki/Plop_Boot_Manager" title="Plop Boot Manager">Plop Boot Manager</a></span></li> <li><span class="nowrap"><a href="/wiki/MILO_(bootloader)" title="MILO (bootloader)">MILO</a></span></li></ul> </div></td></tr></tbody></table><div> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Partition layouts</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><span class="nowrap"><a href="/wiki/GUID_Partition_Table" title="GUID Partition Table">GUID Partition Table</a></span></li> <li><span class="nowrap"><a href="/wiki/Master_boot_record" title="Master boot record">Master boot record</a></span></li> <li><span class="nowrap"><a href="/wiki/Apple_Partition_Map" title="Apple Partition Map">Apple Partition Map</a></span></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/System_partition_and_boot_partition" title="System partition and boot partition">Partitions</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><span class="nowrap"><a href="/wiki/EFI_system_partition" title="EFI system partition">EFI system partition</a></span></li> <li><span class="nowrap"><a href="/wiki/BIOS_boot_partition" title="BIOS boot partition">BIOS boot partition</a></span></li> <li><span class="nowrap"><a href="/wiki//boot/" title="/boot/">/boot/</a></span></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Utilities</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Software</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><span class="nowrap"><a href="/wiki/Flashrom_(utility)" title="Flashrom (utility)">flashrom</a></span></li> <li><span class="nowrap"><a href="/wiki/Fwupd" title="Fwupd">fwupd</a></span></li> <li><span class="nowrap"><a href="/wiki/UEFITool" title="UEFITool">UEFITool</a></span></li> <li><span class="nowrap"><a href="/wiki/Odin_(firmware_flashing_software)" title="Odin (firmware flashing software)">Odin</a></span> <ul><li><span class="nowrap"><a href="/wiki/Odin_(firmware_flashing_software)#Heimdall" title="Odin (firmware flashing software)">Heimdall</a></span></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Hardware</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><span class="nowrap"><a href="/wiki/Bus_Pirate" title="Bus Pirate">Bus Pirate</a></span></li> <li><span class="nowrap"><a href="/wiki/Raspberry_Pi" title="Raspberry Pi">Raspberry Pi</a></span></li> <li><span class="nowrap"><a href="/wiki/FTDI" title="FTDI">ft2232</a></span></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Network_booting" title="Network booting">Network boot</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><span class="nowrap"><a href="/wiki/Preboot_Execution_Environment" title="Preboot Execution Environment">Preboot Execution Environment</a></span> <ul><li><span class="nowrap"><a href="/wiki/GPXE" title="GPXE">gPXE</a></span></li> <li><span class="nowrap"><a href="/wiki/IPXE" title="IPXE">iPXE</a></span></li></ul></li> <li><span class="nowrap"><a href="/wiki/NetBoot" title="NetBoot">NetBoot</a></span></li> <li><span class="nowrap"><a href="/wiki/Remote_Initial_Program_Load" title="Remote Initial Program Load">Remote Initial Program Load</a></span></li> <li><span class="nowrap"><a href="/wiki/Wake-on-LAN" title="Wake-on-LAN">Wake-on-LAN</a></span></li> <li><span class="nowrap"><a href="/wiki/Wake-on-ring" title="Wake-on-ring">Wake-on-ring</a></span></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">ROM variants</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><span class="nowrap"><a href="/wiki/Read-only_memory" title="Read-only memory">ROM</a></span></li> <li><span class="nowrap"><a href="/wiki/Programmable_ROM" title="Programmable ROM">PROM</a></span></li> <li><span class="nowrap"><a href="/wiki/EPROM" title="EPROM">EPROM</a></span></li> <li><span class="nowrap"><a href="/wiki/EEPROM" title="EEPROM">EEPROM</a></span></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Related</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><span class="nowrap"><a href="/wiki/Boot_ROM" title="Boot ROM">Boot ROM</a></span></li> <li><span class="nowrap"><a href="/wiki/ROM_hacking" title="ROM hacking">ROM hacking</a></span></li> <li><span class="nowrap"><a href="/wiki/ROM_image" title="ROM image">ROM image</a></span></li> <li><span class="nowrap"><a href="/wiki/Execute_in_place" title="Execute in place">Execute in place</a></span></li> <li><span class="nowrap"><a href="/wiki/Devicetree" title="Devicetree">Devicetree</a></span></li> <li><span class="nowrap"><a href="/wiki/Fastboot" title="Fastboot">Fastboot</a></span></li> <li><span class="nowrap"><a href="/wiki/Instant-on" title="Instant-on">Instant-on</a></span></li> <li><span class="nowrap"><a href="/wiki/Power-on_self-test" title="Power-on self-test">Power-on self-test</a></span></li> <li><span class="nowrap"><a href="/wiki/Qualcomm_EDL_mode" title="Qualcomm EDL mode">EDL mode</a></span></li></ul> </div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"><style data-mw-deduplicate="TemplateStyles:r1038841319">.mw-parser-output .tooltip-dotted{border-bottom:1px dotted;cursor:help}</style><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1038841319"></div><div role="navigation" class="navbox authority-control" aria-label="Navbox" style="padding:3px"><table class="nowraplinks hlist navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Help:Authority_control" title="Help:Authority control">Authority control databases</a>: National <span class="mw-valign-text-top noprint" typeof="mw:File/Frameless"><a href="https://www.wikidata.org/wiki/Q226264#identifiers" title="Edit this at Wikidata"><img alt="Edit this at Wikidata" src="//upload.wikimedia.org/wikipedia/en/thumb/8/8a/OOjs_UI_icon_edit-ltr-progressive.svg/10px-OOjs_UI_icon_edit-ltr-progressive.svg.png" decoding="async" width="10" height="10" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/8/8a/OOjs_UI_icon_edit-ltr-progressive.svg/15px-OOjs_UI_icon_edit-ltr-progressive.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/8/8a/OOjs_UI_icon_edit-ltr-progressive.svg/20px-OOjs_UI_icon_edit-ltr-progressive.svg.png 2x" data-file-width="20" data-file-height="20" /></a></span></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"><ul><li><span class="uid"><a rel="nofollow" class="external text" href="https://d-nb.info/gnd/4202226-5">Germany</a></span></li><li><span class="uid"><span class="rt-commentedText tooltip tooltip-dotted" title="Basic input-output systems"><a rel="nofollow" class="external text" href="https://id.loc.gov/authorities/sh2017005165">United States</a></span></span></li><li><span class="uid"><span class="rt-commentedText tooltip tooltip-dotted" title="BIOS (rozhraní)"><a rel="nofollow" class="external text" href="https://aleph.nkp.cz/F/?func=find-c&local_base=aut&ccl_term=ica=ph117378&CON_LNG=ENG">Czech Republic</a></span></span></li><li><span class="uid"><a rel="nofollow" class="external text" href="http://olduli.nli.org.il/F/?func=find-b&local_base=NLX10&find_code=UID&request=987012575146205171">Israel</a></span></li></ul></div></td></tr></tbody></table></div>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?type=1x1" alt="" width="1" height="1" style="border: none; position: absolute;"></noscript> <div class="printfooter" data-nosnippet="">Retrieved from "<a dir="ltr" href="https://en.wikipedia.org/w/index.php?title=BIOS&oldid=1259081847">https://en.wikipedia.org/w/index.php?title=BIOS&oldid=1259081847</a>"</div></div> <div id="catlinks" class="catlinks" data-mw="interface"><div id="mw-normal-catlinks" class="mw-normal-catlinks"><a href="/wiki/Help:Category" title="Help:Category">Categories</a>: <ul><li><a href="/wiki/Category:BIOS" 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