CINXE.COM

<!DOCTYPE html> <html class="client-nojs vector-feature-language-in-header-enabled vector-feature-language-in-main-page-header-disabled vector-feature-sticky-header-disabled vector-feature-page-tools-pinned-disabled vector-feature-toc-pinned-clientpref-1 vector-feature-main-menu-pinned-disabled vector-feature-limited-width-clientpref-1 vector-feature-limited-width-content-enabled vector-feature-custom-font-size-clientpref-1 vector-feature-appearance-pinned-clientpref-1 vector-feature-night-mode-enabled skin-theme-clientpref-day vector-toc-available" lang="en" dir="ltr"> <head> <meta charset="UTF-8"> <title>File Control Block - Wikipedia</title> <script>(function(){var className="client-js vector-feature-language-in-header-enabled vector-feature-language-in-main-page-header-disabled vector-feature-sticky-header-disabled vector-feature-page-tools-pinned-disabled vector-feature-toc-pinned-clientpref-1 vector-feature-main-menu-pinned-disabled vector-feature-limited-width-clientpref-1 vector-feature-limited-width-content-enabled vector-feature-custom-font-size-clientpref-1 vector-feature-appearance-pinned-clientpref-1 vector-feature-night-mode-enabled skin-theme-clientpref-day vector-toc-available";var cookie=document.cookie.match(/(?:^|; )enwikimwclientpreferences=([^;]+)/);if(cookie){cookie[1].split('%2C').forEach(function(pref){className=className.replace(new RegExp('(^| )'+pref.replace(/-clientpref-\w+$|[^\w-]+/g,'')+'-clientpref-\\w+( |$)'),'$1'+pref+'$2');});}document.documentElement.className=className;}());RLCONF={"wgBreakFrames":false,"wgSeparatorTransformTable":["",""],"wgDigitTransformTable":["",""],"wgDefaultDateFormat":"dmy", "wgMonthNames":["","January","February","March","April","May","June","July","August","September","October","November","December"],"wgRequestId":"14de036c-71bf-4fd9-82cb-b016c35edb06","wgCanonicalNamespace":"","wgCanonicalSpecialPageName":false,"wgNamespaceNumber":0,"wgPageName":"File_Control_Block","wgTitle":"File Control Block","wgCurRevisionId":1116761064,"wgRevisionId":1116761064,"wgArticleId":1269014,"wgIsArticle":true,"wgIsRedirect":false,"wgAction":"view","wgUserName":null,"wgUserGroups":["*"],"wgCategories":["CS1 Spanish-language sources (es)","CS1 errors: periodical ignored","CS1 German-language sources (de)","Articles needing additional references from January 2014","All articles needing additional references","Wikipedia articles that are too technical from October 2022","All articles that are too technical","Articles with multiple maintenance issues","Use dmy dates from May 2019","Disk file systems","CP/M technology","DOS technology"],"wgPageViewLanguage":"en", "wgPageContentLanguage":"en","wgPageContentModel":"wikitext","wgRelevantPageName":"File_Control_Block","wgRelevantArticleId":1269014,"wgIsProbablyEditable":true,"wgRelevantPageIsProbablyEditable":true,"wgRestrictionEdit":[],"wgRestrictionMove":[],"wgNoticeProject":"wikipedia","wgCiteReferencePreviewsActive":false,"wgFlaggedRevsParams":{"tags":{"status":{"levels":1}}},"wgMediaViewerOnClick":true,"wgMediaViewerEnabledByDefault":true,"wgPopupsFlags":0,"wgVisualEditor":{"pageLanguageCode":"en","pageLanguageDir":"ltr","pageVariantFallbacks":"en"},"wgMFDisplayWikibaseDescriptions":{"search":true,"watchlist":true,"tagline":false,"nearby":true},"wgWMESchemaEditAttemptStepOversample":false,"wgWMEPageLength":20000,"wgRelatedArticlesCompat":[],"wgCentralAuthMobileDomain":false,"wgEditSubmitButtonLabelPublish":true,"wgULSPosition":"interlanguage","wgULSisCompactLinksEnabled":false,"wgVector2022LanguageInHeader":true,"wgULSisLanguageSelectorEmpty":false,"wgWikibaseItemId":"Q1412592", "wgCheckUserClientHintsHeadersJsApi":["brands","architecture","bitness","fullVersionList","mobile","model","platform","platformVersion"],"GEHomepageSuggestedEditsEnableTopics":true,"wgGETopicsMatchModeEnabled":false,"wgGEStructuredTaskRejectionReasonTextInputEnabled":false,"wgGELevelingUpEnabledForUser":false};RLSTATE={"ext.globalCssJs.user.styles":"ready","site.styles":"ready","user.styles":"ready","ext.globalCssJs.user":"ready","user":"ready","user.options":"loading","ext.cite.styles":"ready","skins.vector.search.codex.styles":"ready","skins.vector.styles":"ready","skins.vector.icons":"ready","jquery.makeCollapsible.styles":"ready","ext.wikimediamessages.styles":"ready","ext.visualEditor.desktopArticleTarget.noscript":"ready","ext.uls.interlanguage":"ready","wikibase.client.init":"ready","ext.wikimediaBadges":"ready"};RLPAGEMODULES=["ext.cite.ux-enhancements","site","mediawiki.page.ready","jquery.makeCollapsible","mediawiki.toc","skins.vector.js","ext.centralNotice.geoIP", "ext.centralNotice.startUp","ext.gadget.ReferenceTooltips","ext.gadget.switcher","ext.urlShortener.toolbar","ext.centralauth.centralautologin","mmv.bootstrap","ext.popups","ext.visualEditor.desktopArticleTarget.init","ext.visualEditor.targetLoader","ext.echo.centralauth","ext.eventLogging","ext.wikimediaEvents","ext.navigationTiming","ext.uls.interface","ext.cx.eventlogging.campaigns","ext.cx.uls.quick.actions","wikibase.client.vector-2022","ext.checkUser.clientHints","ext.quicksurveys.init","ext.growthExperiments.SuggestedEditSession","wikibase.sidebar.tracking"];</script> <script>(RLQ=window.RLQ||[]).push(function(){mw.loader.impl(function(){return["user.options@12s5i",function($,jQuery,require,module){mw.user.tokens.set({"patrolToken":"+\\","watchToken":"+\\","csrfToken":"+\\"}); }];});});</script> <link rel="stylesheet" href="/w/load.php?lang=en&modules=ext.cite.styles%7Cext.uls.interlanguage%7Cext.visualEditor.desktopArticleTarget.noscript%7Cext.wikimediaBadges%7Cext.wikimediamessages.styles%7Cjquery.makeCollapsible.styles%7Cskins.vector.icons%2Cstyles%7Cskins.vector.search.codex.styles%7Cwikibase.client.init&only=styles&skin=vector-2022"> <script async="" src="/w/load.php?lang=en&modules=startup&only=scripts&raw=1&skin=vector-2022"></script> <meta name="ResourceLoaderDynamicStyles" content=""> <link rel="stylesheet" href="/w/load.php?lang=en&modules=site.styles&only=styles&skin=vector-2022"> <meta name="generator" content="MediaWiki 1.44.0-wmf.4"> <meta name="referrer" content="origin"> <meta name="referrer" content="origin-when-cross-origin"> <meta name="robots" content="max-image-preview:standard"> <meta name="format-detection" content="telephone=no"> <meta name="viewport" content="width=1120"> <meta property="og:title" content="File Control Block - Wikipedia"> <meta property="og:type" content="website"> <link rel="preconnect" href="//upload.wikimedia.org"> <link rel="alternate" media="only screen and (max-width: 640px)" href="//en.m.wikipedia.org/wiki/File_Control_Block"> <link rel="alternate" type="application/x-wiki" title="Edit this page" href="/w/index.php?title=File_Control_Block&action=edit"> <link rel="apple-touch-icon" href="/static/apple-touch/wikipedia.png"> <link rel="icon" href="/static/favicon/wikipedia.ico"> <link rel="search" type="application/opensearchdescription+xml" href="/w/rest.php/v1/search" title="Wikipedia (en)"> <link rel="EditURI" type="application/rsd+xml" href="//en.wikipedia.org/w/api.php?action=rsd"> <link rel="canonical" href="https://en.wikipedia.org/wiki/File_Control_Block"> <link rel="license" href="https://creativecommons.org/licenses/by-sa/4.0/deed.en"> <link rel="alternate" type="application/atom+xml" title="Wikipedia Atom feed" href="/w/index.php?title=Special:RecentChanges&feed=atom"> <link rel="dns-prefetch" href="//meta.wikimedia.org" /> <link rel="dns-prefetch" href="//login.wikimedia.org"> </head> <body class="skin--responsive skin-vector skin-vector-search-vue mediawiki ltr sitedir-ltr mw-hide-empty-elt ns-0 ns-subject mw-editable page-File_Control_Block rootpage-File_Control_Block skin-vector-2022 action-view"><a class="mw-jump-link" href="#bodyContent">Jump to content</a> <div class="vector-header-container"> <header class="vector-header mw-header"> <div class="vector-header-start"> <nav class="vector-main-menu-landmark" aria-label="Site"> <div id="vector-main-menu-dropdown" class="vector-dropdown vector-main-menu-dropdown vector-button-flush-left vector-button-flush-right" > <input type="checkbox" id="vector-main-menu-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-main-menu-dropdown" class="vector-dropdown-checkbox " aria-label="Main menu" > <label id="vector-main-menu-dropdown-label" for="vector-main-menu-dropdown-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-menu mw-ui-icon-wikimedia-menu"></span> <span class="vector-dropdown-label-text">Main menu</span> </label> <div class="vector-dropdown-content"> <div id="vector-main-menu-unpinned-container" class="vector-unpinned-container"> <div id="vector-main-menu" class="vector-main-menu vector-pinnable-element"> <div class="vector-pinnable-header vector-main-menu-pinnable-header vector-pinnable-header-unpinned" data-feature-name="main-menu-pinned" data-pinnable-element-id="vector-main-menu" data-pinned-container-id="vector-main-menu-pinned-container" data-unpinned-container-id="vector-main-menu-unpinned-container" > <div class="vector-pinnable-header-label">Main menu</div> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-main-menu.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-main-menu.unpin">hide</button> </div> <div id="p-navigation" class="vector-menu mw-portlet mw-portlet-navigation" > <div class="vector-menu-heading"> Navigation </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="n-mainpage-description" class="mw-list-item"><a href="/wiki/Main_Page" title="Visit the main page [z]" accesskey="z"><span>Main page</span></a></li><li id="n-contents" class="mw-list-item"><a href="/wiki/Wikipedia:Contents" title="Guides to browsing Wikipedia"><span>Contents</span></a></li><li id="n-currentevents" class="mw-list-item"><a href="/wiki/Portal:Current_events" title="Articles related to current events"><span>Current events</span></a></li><li id="n-randompage" class="mw-list-item"><a href="/wiki/Special:Random" title="Visit a randomly selected article [x]" accesskey="x"><span>Random article</span></a></li><li id="n-aboutsite" class="mw-list-item"><a href="/wiki/Wikipedia:About" title="Learn about Wikipedia and how it works"><span>About Wikipedia</span></a></li><li id="n-contactpage" class="mw-list-item"><a href="//en.wikipedia.org/wiki/Wikipedia:Contact_us" title="How to contact Wikipedia"><span>Contact us</span></a></li> </ul> </div> </div> <div id="p-interaction" class="vector-menu mw-portlet mw-portlet-interaction" > <div class="vector-menu-heading"> Contribute </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="n-help" class="mw-list-item"><a href="/wiki/Help:Contents" title="Guidance on how to use and edit Wikipedia"><span>Help</span></a></li><li id="n-introduction" class="mw-list-item"><a href="/wiki/Help:Introduction" title="Learn how to edit Wikipedia"><span>Learn to edit</span></a></li><li id="n-portal" class="mw-list-item"><a href="/wiki/Wikipedia:Community_portal" title="The hub for editors"><span>Community portal</span></a></li><li id="n-recentchanges" class="mw-list-item"><a href="/wiki/Special:RecentChanges" title="A list of recent changes to Wikipedia [r]" accesskey="r"><span>Recent changes</span></a></li><li id="n-upload" class="mw-list-item"><a href="/wiki/Wikipedia:File_upload_wizard" title="Add images or other media for use on Wikipedia"><span>Upload file</span></a></li> </ul> </div> </div> </div> </div> </div> </div> </nav> <a href="/wiki/Main_Page" class="mw-logo"> <img class="mw-logo-icon" src="/static/images/icons/wikipedia.png" alt="" aria-hidden="true" height="50" width="50"> <span class="mw-logo-container skin-invert"> <img class="mw-logo-wordmark" alt="Wikipedia" src="/static/images/mobile/copyright/wikipedia-wordmark-en.svg" style="width: 7.5em; height: 1.125em;"> <img class="mw-logo-tagline" alt="The Free Encyclopedia" src="/static/images/mobile/copyright/wikipedia-tagline-en.svg" width="117" height="13" style="width: 7.3125em; height: 0.8125em;"> </span> </a> </div> <div class="vector-header-end"> <div id="p-search" role="search" class="vector-search-box-vue vector-search-box-collapses vector-search-box-show-thumbnail vector-search-box-auto-expand-width vector-search-box"> <a href="/wiki/Special:Search" class="cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only search-toggle" title="Search Wikipedia [f]" accesskey="f"><span class="vector-icon mw-ui-icon-search mw-ui-icon-wikimedia-search"></span> <span>Search</span> </a> <div class="vector-typeahead-search-container"> <div class="cdx-typeahead-search cdx-typeahead-search--show-thumbnail cdx-typeahead-search--auto-expand-width"> <form action="/w/index.php" id="searchform" class="cdx-search-input cdx-search-input--has-end-button"> <div id="simpleSearch" class="cdx-search-input__input-wrapper" data-search-loc="header-moved"> <div class="cdx-text-input cdx-text-input--has-start-icon"> <input class="cdx-text-input__input" type="search" name="search" placeholder="Search Wikipedia" aria-label="Search Wikipedia" autocapitalize="sentences" title="Search Wikipedia [f]" accesskey="f" id="searchInput" > <span class="cdx-text-input__icon cdx-text-input__start-icon"></span> </div> <input type="hidden" name="title" value="Special:Search"> </div> <button class="cdx-button cdx-search-input__end-button">Search</button> </form> </div> </div> </div> <nav class="vector-user-links vector-user-links-wide" aria-label="Personal tools"> <div class="vector-user-links-main"> <div id="p-vector-user-menu-preferences" class="vector-menu mw-portlet emptyPortlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> </ul> </div> </div> <div id="p-vector-user-menu-userpage" class="vector-menu mw-portlet emptyPortlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> </ul> </div> </div> <nav class="vector-appearance-landmark" aria-label="Appearance"> <div id="vector-appearance-dropdown" class="vector-dropdown " title="Change the appearance of the page's font size, width, and color" > <input type="checkbox" id="vector-appearance-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-appearance-dropdown" class="vector-dropdown-checkbox " aria-label="Appearance" > <label id="vector-appearance-dropdown-label" for="vector-appearance-dropdown-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-appearance mw-ui-icon-wikimedia-appearance"></span> <span class="vector-dropdown-label-text">Appearance</span> </label> <div class="vector-dropdown-content"> <div id="vector-appearance-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <div id="p-vector-user-menu-notifications" class="vector-menu mw-portlet emptyPortlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> </ul> </div> </div> <div id="p-vector-user-menu-overflow" class="vector-menu mw-portlet" > <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=File+Control+Block" 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=File+Control+Block" title="You're encouraged to log in; however, it's not mandatory. [o]" accesskey="o" class=""><span>Log in</span></a> </li> </ul> </div> </div> </div> <div id="vector-user-links-dropdown" class="vector-dropdown vector-user-menu vector-button-flush-right vector-user-menu-logged-out" title="Log in and more options" > <input type="checkbox" id="vector-user-links-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-user-links-dropdown" class="vector-dropdown-checkbox " aria-label="Personal tools" > <label id="vector-user-links-dropdown-label" for="vector-user-links-dropdown-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-ellipsis mw-ui-icon-wikimedia-ellipsis"></span> <span class="vector-dropdown-label-text">Personal tools</span> </label> <div class="vector-dropdown-content"> <div id="p-personal" class="vector-menu mw-portlet mw-portlet-personal user-links-collapsible-item" title="User menu" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="pt-sitesupport" class="user-links-collapsible-item mw-list-item"><a href="https://donate.wikimedia.org/wiki/Special:FundraiserRedirector?utm_source=donate&utm_medium=sidebar&utm_campaign=C13_en.wikipedia.org&uselang=en"><span>Donate</span></a></li><li id="pt-createaccount" class="user-links-collapsible-item mw-list-item"><a href="/w/index.php?title=Special:CreateAccount&returnto=File+Control+Block" title="You are encouraged to create an account and log in; however, it is not mandatory"><span class="vector-icon mw-ui-icon-userAdd mw-ui-icon-wikimedia-userAdd"></span> <span>Create account</span></a></li><li id="pt-login" class="user-links-collapsible-item mw-list-item"><a href="/w/index.php?title=Special:UserLogin&returnto=File+Control+Block" title="You're encouraged to log in; however, it's not mandatory. [o]" accesskey="o"><span class="vector-icon mw-ui-icon-logIn mw-ui-icon-wikimedia-logIn"></span> <span>Log in</span></a></li> </ul> </div> </div> <div id="p-user-menu-anon-editor" class="vector-menu mw-portlet mw-portlet-user-menu-anon-editor" > <div class="vector-menu-heading"> Pages for logged out editors <a href="/wiki/Help:Introduction" aria-label="Learn more about editing"><span>learn more</span></a> </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="pt-anoncontribs" class="mw-list-item"><a href="/wiki/Special:MyContributions" title="A list of edits made from this IP address [y]" accesskey="y"><span>Contributions</span></a></li><li id="pt-anontalk" class="mw-list-item"><a href="/wiki/Special:MyTalk" title="Discussion about edits from this IP address [n]" accesskey="n"><span>Talk</span></a></li> </ul> </div> </div> </div> </div> </nav> </div> </header> </div> <div class="mw-page-container"> <div class="mw-page-container-inner"> <div class="vector-sitenotice-container"> <div id="siteNotice"></div> </div> <div class="vector-column-start"> <div class="vector-main-menu-container"> <div id="mw-navigation"> <nav id="mw-panel" class="vector-main-menu-landmark" aria-label="Site"> <div id="vector-main-menu-pinned-container" class="vector-pinned-container"> </div> </nav> </div> </div> <div class="vector-sticky-pinned-container"> <nav id="mw-panel-toc" aria-label="Contents" data-event-name="ui.sidebar-toc" class="mw-table-of-contents-container vector-toc-landmark"> <div id="vector-toc-pinned-container" class="vector-pinned-container"> <div id="vector-toc" class="vector-toc vector-pinnable-element"> <div class="vector-pinnable-header vector-toc-pinnable-header vector-pinnable-header-pinned" data-feature-name="toc-pinned" data-pinnable-element-id="vector-toc" > <h2 class="vector-pinnable-header-label">Contents</h2> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" 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-Usage" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Usage"> <div class="vector-toc-text"> <span class="vector-toc-numb">1</span> <span>Usage</span> </div> </a> <ul id="toc-Usage-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Disk_Transfer_Area" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Disk_Transfer_Area"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Disk Transfer Area</span> </div> </a> <ul id="toc-Disk_Transfer_Area-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Program_Segment_Prefix_&_Program_Initialisation" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Program_Segment_Prefix_&_Program_Initialisation"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Program Segment Prefix & Program Initialisation</span> </div> </a> <ul id="toc-Program_Segment_Prefix_&_Program_Initialisation-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</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 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Further_reading"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>Further reading</span> </div> </a> <ul id="toc-Further_reading-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">File Control Block</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 6 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-6" 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">6 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/File_control_block" title="File control block – Catalan" lang="ca" hreflang="ca" data-title="File control block" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/File_Control_Block" title="File Control Block – German" lang="de" hreflang="de" data-title="File Control Block" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/File_control_block" title="File control block – Spanish" lang="es" hreflang="es" data-title="File control block" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%ED%8C%8C%EC%9D%BC_%EC%A0%9C%EC%96%B4_%EB%B8%94%EB%A1%9D" title="파일 제어 블록 – Korean" lang="ko" hreflang="ko" data-title="파일 제어 블록" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-kk mw-list-item"><a href="https://kk.wikipedia.org/wiki/%D0%A4%D0%B0%D0%B9%D0%BB%D0%B4%D1%8B_%D0%B1%D0%B0%D1%81%D2%9B%D0%B0%D1%80%D1%83_%D0%B1%D0%BB%D0%BE%D0%B3%D1%8B" title="Файлды басқару блогы – Kazakh" lang="kk" hreflang="kk" data-title="Файлды басқару блогы" data-language-autonym="Қазақша" data-language-local-name="Kazakh" class="interlanguage-link-target"><span>Қазақша</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%91%D0%BB%D0%BE%D0%BA_%D1%83%D0%BF%D1%80%D0%B0%D0%B2%D0%BB%D0%B5%D0%BD%D0%B8%D1%8F_%D1%84%D0%B0%D0%B9%D0%BB%D0%BE%D0%BC" title="Блок управления файлом – Russian" lang="ru" hreflang="ru" data-title="Блок управления файлом" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</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/Q1412592#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 class="vector-menu-content-list"> <li id="ca-nstab-main" class="selected vector-tab-noicon mw-list-item"><a href="/wiki/File_Control_Block" title="View the content page [c]" accesskey="c"><span>Article</span></a></li><li id="ca-talk" class="vector-tab-noicon mw-list-item"><a href="/wiki/Talk:File_Control_Block" rel="discussion" title="Discuss improvements to the content page [t]" accesskey="t"><span>Talk</span></a></li> </ul> </div> </div> <div id="vector-variants-dropdown" class="vector-dropdown emptyPortlet" > <input type="checkbox" id="vector-variants-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-variants-dropdown" class="vector-dropdown-checkbox " aria-label="Change language variant" > <label id="vector-variants-dropdown-label" for="vector-variants-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet" aria-hidden="true" ><span class="vector-dropdown-label-text">English</span> </label> <div class="vector-dropdown-content"> <div id="p-variants" class="vector-menu mw-portlet mw-portlet-variants emptyPortlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> </ul> </div> </div> </div> </div> </nav> </div> <div id="right-navigation" class="vector-collapsible"> <nav aria-label="Views"> <div id="p-views" class="vector-menu vector-menu-tabs mw-portlet mw-portlet-views" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="ca-view" class="selected vector-tab-noicon mw-list-item"><a href="/wiki/File_Control_Block"><span>Read</span></a></li><li id="ca-edit" class="vector-tab-noicon mw-list-item"><a href="/w/index.php?title=File_Control_Block&action=edit" title="Edit this page [e]" accesskey="e"><span>Edit</span></a></li><li id="ca-history" class="vector-tab-noicon mw-list-item"><a href="/w/index.php?title=File_Control_Block&action=history" title="Past revisions of this page [h]" accesskey="h"><span>View history</span></a></li> </ul> </div> </div> </nav> <nav class="vector-page-tools-landmark" aria-label="Page tools"> <div id="vector-page-tools-dropdown" class="vector-dropdown vector-page-tools-dropdown" > <input type="checkbox" id="vector-page-tools-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-tools-dropdown" class="vector-dropdown-checkbox " aria-label="Tools" > <label id="vector-page-tools-dropdown-label" for="vector-page-tools-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet" aria-hidden="true" ><span class="vector-dropdown-label-text">Tools</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-tools-unpinned-container" class="vector-unpinned-container"> <div id="vector-page-tools" class="vector-page-tools vector-pinnable-element"> <div class="vector-pinnable-header vector-page-tools-pinnable-header vector-pinnable-header-unpinned" data-feature-name="page-tools-pinned" data-pinnable-element-id="vector-page-tools" data-pinned-container-id="vector-page-tools-pinned-container" data-unpinned-container-id="vector-page-tools-unpinned-container" > <div class="vector-pinnable-header-label">Tools</div> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-page-tools.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-page-tools.unpin">hide</button> </div> <div id="p-cactions" class="vector-menu mw-portlet mw-portlet-cactions emptyPortlet vector-has-collapsible-items" title="More options" > <div class="vector-menu-heading"> Actions </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="ca-more-view" class="selected vector-more-collapsible-item mw-list-item"><a href="/wiki/File_Control_Block"><span>Read</span></a></li><li id="ca-more-edit" class="vector-more-collapsible-item mw-list-item"><a href="/w/index.php?title=File_Control_Block&action=edit" title="Edit this page [e]" accesskey="e"><span>Edit</span></a></li><li id="ca-more-history" class="vector-more-collapsible-item mw-list-item"><a href="/w/index.php?title=File_Control_Block&action=history"><span>View history</span></a></li> </ul> </div> </div> <div id="p-tb" class="vector-menu mw-portlet mw-portlet-tb" > <div class="vector-menu-heading"> General </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="t-whatlinkshere" class="mw-list-item"><a href="/wiki/Special:WhatLinksHere/File_Control_Block" title="List of all English Wikipedia pages containing links to this page [j]" accesskey="j"><span>What links here</span></a></li><li id="t-recentchangeslinked" class="mw-list-item"><a href="/wiki/Special:RecentChangesLinked/File_Control_Block" rel="nofollow" title="Recent changes in pages linked from this page [k]" accesskey="k"><span>Related changes</span></a></li><li id="t-upload" class="mw-list-item"><a href="/wiki/Wikipedia:File_Upload_Wizard" title="Upload files [u]" accesskey="u"><span>Upload file</span></a></li><li id="t-specialpages" class="mw-list-item"><a href="/wiki/Special:SpecialPages" title="A list of all special pages [q]" accesskey="q"><span>Special pages</span></a></li><li id="t-permalink" class="mw-list-item"><a href="/w/index.php?title=File_Control_Block&oldid=1116761064" title="Permanent link to this revision of this page"><span>Permanent link</span></a></li><li id="t-info" class="mw-list-item"><a href="/w/index.php?title=File_Control_Block&action=info" title="More information about this page"><span>Page information</span></a></li><li id="t-cite" class="mw-list-item"><a href="/w/index.php?title=Special:CiteThisPage&page=File_Control_Block&id=1116761064&wpFormIdentifier=titleform" title="Information on how to cite this page"><span>Cite this page</span></a></li><li id="t-urlshortener" class="mw-list-item"><a href="/w/index.php?title=Special:UrlShortener&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FFile_Control_Block"><span>Get shortened URL</span></a></li><li id="t-urlshortener-qrcode" class="mw-list-item"><a href="/w/index.php?title=Special:QrCode&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FFile_Control_Block"><span>Download QR code</span></a></li> </ul> </div> </div> <div id="p-coll-print_export" class="vector-menu mw-portlet mw-portlet-coll-print_export" > <div class="vector-menu-heading"> Print/export </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="coll-download-as-rl" class="mw-list-item"><a href="/w/index.php?title=Special:DownloadAsPdf&page=File_Control_Block&action=show-download-screen" title="Download this page as a PDF file"><span>Download as PDF</span></a></li><li id="t-print" class="mw-list-item"><a href="/w/index.php?title=File_Control_Block&printable=yes" title="Printable version of this page [p]" accesskey="p"><span>Printable version</span></a></li> </ul> </div> </div> <div id="p-wikibase-otherprojects" class="vector-menu mw-portlet mw-portlet-wikibase-otherprojects" > <div class="vector-menu-heading"> In other projects </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="t-wikibase" class="wb-otherproject-link wb-otherproject-wikibase-dataitem mw-list-item"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q1412592" title="Structured data on this page hosted by Wikidata [g]" accesskey="g"><span>Wikidata item</span></a></li> </ul> </div> </div> </div> </div> </div> </div> </nav> </div> </div> </div> <div class="vector-column-end"> <div class="vector-sticky-pinned-container"> <nav class="vector-page-tools-landmark" aria-label="Page tools"> <div id="vector-page-tools-pinned-container" class="vector-pinned-container"> </div> </nav> <nav class="vector-appearance-landmark" aria-label="Appearance"> <div id="vector-appearance-pinned-container" class="vector-pinned-container"> <div id="vector-appearance" class="vector-appearance vector-pinnable-element"> <div class="vector-pinnable-header vector-appearance-pinnable-header vector-pinnable-header-pinned" data-feature-name="appearance-pinned" data-pinnable-element-id="vector-appearance" data-pinned-container-id="vector-appearance-pinned-container" data-unpinned-container-id="vector-appearance-unpinned-container" > <div class="vector-pinnable-header-label">Appearance</div> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-appearance.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-appearance.unpin">hide</button> </div> </div> </div> </nav> </div> </div> <div id="bodyContent" 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"><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><style data-mw-deduplicate="TemplateStyles:r1248332772">.mw-parser-output .multiple-issues-text{width:95%;margin:0.2em 0}.mw-parser-output .multiple-issues-text>.mw-collapsible-content{margin-top:0.3em}.mw-parser-output .compact-ambox .ambox{border:none;border-collapse:collapse;background-color:transparent;margin:0 0 0 1.6em!important;padding:0!important;width:auto;display:block}body.mediawiki .mw-parser-output .compact-ambox .ambox.mbox-small-left{font-size:100%;width:auto;margin:0}.mw-parser-output .compact-ambox .ambox .mbox-text{padding:0!important;margin:0!important}.mw-parser-output .compact-ambox .ambox .mbox-text-span{display:list-item;line-height:1.5em;list-style-type:disc}body.skin-minerva .mw-parser-output .multiple-issues-text>.mw-collapsible-toggle,.mw-parser-output .compact-ambox .ambox .mbox-image,.mw-parser-output .compact-ambox .ambox .mbox-imageright,.mw-parser-output .compact-ambox .ambox .mbox-empty-cell,.mw-parser-output .compact-ambox .hide-when-compact{display:none}</style><table class="box-Multiple_issues plainlinks metadata ambox ambox-content ambox-multiple_issues compact-ambox" role="presentation"><tbody><tr><td class="mbox-image"><div class="mbox-image-div"><span typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/b/b4/Ambox_important.svg/40px-Ambox_important.svg.png" decoding="async" width="40" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/b/b4/Ambox_important.svg/60px-Ambox_important.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/b/b4/Ambox_important.svg/80px-Ambox_important.svg.png 2x" data-file-width="40" data-file-height="40" /></span></span></div></td><td class="mbox-text"><div class="mbox-text-span"><div class="multiple-issues-text mw-collapsible"><b>This article has multiple issues.</b> Please help <b><a href="/wiki/Special:EditPage/File_Control_Block" title="Special:EditPage/File Control Block">improve it</a></b> or discuss these issues on the <b><a href="/wiki/Talk:File_Control_Block" title="Talk:File Control Block">talk page</a></b>. <small><i>(<a href="/wiki/Help:Maintenance_template_removal" title="Help:Maintenance template removal">Learn how and when to remove these messages</a>)</i></small> <div class="mw-collapsible-content"> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1251242444"><table class="box-More_citations_needed 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 article <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/File_Control_Block" title="Special:EditPage/File Control Block">improve this article</a> by <a href="/wiki/Help:Referencing_for_beginners" title="Help:Referencing for beginners">adding citations to reliable sources</a>. Unsourced material may be challenged and removed.<br /><small><span class="plainlinks"><i>Find sources:</i> <a rel="nofollow" class="external text" href="https://www.google.com/search?as_eq=wikipedia&q=%22File+Control+Block%22">"File Control Block"</a> – <a rel="nofollow" class="external text" href="https://www.google.com/search?tbm=nws&q=%22File+Control+Block%22+-wikipedia&tbs=ar:1">news</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.google.com/search?&q=%22File+Control+Block%22&tbs=bkt:s&tbm=bks">newspapers</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.google.com/search?tbs=bks:1&q=%22File+Control+Block%22+-wikipedia">books</a> <b>·</b> <a rel="nofollow" class="external text" href="https://scholar.google.com/scholar?q=%22File+Control+Block%22">scholar</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.jstor.org/action/doBasicSearch?Query=%22File+Control+Block%22&acc=on&wc=on">JSTOR</a></span></small></span> <span class="date-container"><i>(<span class="date">January 2014</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> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1251242444"><table class="box-Technical plainlinks metadata ambox ambox-style ambox-technical" role="presentation"><tbody><tr><td class="mbox-image"><div class="mbox-image-div"><span typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/f/f2/Edit-clear.svg/40px-Edit-clear.svg.png" decoding="async" width="40" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/f/f2/Edit-clear.svg/60px-Edit-clear.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/f/f2/Edit-clear.svg/80px-Edit-clear.svg.png 2x" data-file-width="48" data-file-height="48" /></span></span></div></td><td class="mbox-text"><div class="mbox-text-span">This article <b>may be too technical for most readers to understand</b>.<span class="hide-when-compact"> Please <a class="external text" href="https://en.wikipedia.org/w/index.php?title=File_Control_Block&action=edit">help improve it</a> to <a href="/wiki/Wikipedia:Make_technical_articles_understandable" title="Wikipedia:Make technical articles understandable">make it understandable to non-experts</a>, without removing the technical details.</span> <span class="date-container"><i>(<span class="date">October 2022</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> </div> </div><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> <p> A <b>File Control Block</b> (<b>FCB</b>) is a file system structure in which the state of an open <a href="/wiki/Computer_file" title="Computer file">file</a> is maintained. A FCB is managed by the operating system, but it resides in the memory of the program that uses the file, not in operating system memory. This allows a process to have as many files open at one time as it wants, provided it can spare enough memory for an FCB per file. </p><p>The FCB originates from <a href="/wiki/CP/M" title="CP/M">CP/M</a> and is also present in most variants of <a href="/wiki/DOS" title="DOS">DOS</a>, though only as a backwards compatibility measure in <a href="/wiki/MS-DOS" title="MS-DOS">MS-DOS</a> versions 2.0 and later. A full FCB is 36 bytes long; in early versions of CP/M, it was 33 bytes. This fixed size, which could not be increased without breaking application compatibility, led to the FCB's eventual demise as the standard method of accessing files. </p><p>The meanings of several of the fields in the FCB differ between CP/M and DOS, and also depending on what operation is being performed. The following fields have consistent meanings:<sup id="cite_ref-stanislavs_1-0" class="reference"><a href="#cite_note-stanislavs-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> </p> <table class="wikitable"> <tbody><tr> <th>Offset</th> <th>Byte<br />size</th> <th>Contents </th></tr> <tr> <td>0x00 </td> <td align="right">1</td> <td>Drive number — 0 for default, 1 for A:, 2 for B:, ... </td></tr> <tr> <td>0x01 </td> <td align="right">8 </td> <td rowspan="2">File name and <a href="/wiki/Filename_extension" title="Filename extension">extension</a> — together these form a <a href="/wiki/8.3_filename" title="8.3 filename">8.3 file name</a>. </td></tr> <tr> <td>0x09 </td> <td align="right">3 </td></tr> <tr> <td>0x0C </td> <td align="right">20</td> <td>Implementation dependent — should be initialised to zero before the FCB is opened. </td></tr> <tr> <td>0x20 </td> <td align="right">1</td> <td>Record number in the current section of the file — used when performing <a href="/wiki/Sequential_access" title="Sequential access">sequential access</a>. </td></tr> <tr> <td>0x21 </td> <td align="right">3</td> <td>Record number to use when performing <a href="/wiki/Random_access" title="Random access">random access</a>. </td></tr></tbody></table> <p>The 20-byte-long field starting at offset 0x0C contained fields which (among others) provided further information about the file:<sup id="cite_ref-Programacion_Ensamblador_MSDOS_2-0" class="reference"><a href="#cite_note-Programacion_Ensamblador_MSDOS-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p> <table class="wikitable"> <tbody><tr> <th>Offset</th> <th>Byte<br />size</th> <th>Contents </th></tr> <tr> <td>0x0E </td> <td align="right">2</td> <td>File's record length in bytes. </td></tr> <tr> <td>0x10 </td> <td align="right">4</td> <td>Total file size in bytes. </td></tr> <tr> <td>0x14 </td> <td align="right">2</td> <td>Date of last modification to file contents. </td></tr> <tr> <td>0x16 </td> <td align="right">2</td> <td>Time of last modification. </td></tr></tbody></table> <p>Further values were used by newer versions of DOS until new information could no longer fit in these 20 bytes. Some preceding "negative offset" bytes were squeezed from reserved spaces in CP/M Zero Page and DOS <a href="/wiki/Program_Segment_Prefix" title="Program Segment Prefix">Program Segment Prefix</a> for storing file attributes.<sup id="cite_ref-stanislavs_1-1" class="reference"><a href="#cite_note-stanislavs-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Usage">Usage</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=File_Control_Block&action=edit&section=1" title="Edit section: Usage"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>In CP/M, <a href="/wiki/86-DOS" title="86-DOS">86-DOS</a> and <a href="/wiki/PC_DOS" class="mw-redirect" title="PC DOS">PC DOS</a> 1.x/MS-DOS 1.xx, the FCB was the only method of accessing files. Under DOS a few INT 21h subfunctions provided the interface to operate on files using the FCB.<sup id="cite_ref-stanislavs_1-2" class="reference"><a href="#cite_note-stanislavs-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Duncan_1988_MS-DOS_Encyclopedia_3-0" class="reference"><a href="#cite_note-Duncan_1988_MS-DOS_Encyclopedia-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Chappell_1994_DOS-Internals_4-0" class="reference"><a href="#cite_note-Chappell_1994_DOS-Internals-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> When, with MS-DOS 2, preparations were made to support multiple processes or users,<sup id="cite_ref-Duncan_1988_MS-DOS_Encyclopedia_3-1" class="reference"><a href="#cite_note-Duncan_1988_MS-DOS_Encyclopedia-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Chappell_1994_DOS-Internals_4-1" class="reference"><a href="#cite_note-Chappell_1994_DOS-Internals-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> use other filesystems<sup id="cite_ref-Duncan_1988_MS-DOS_Encyclopedia_3-2" class="reference"><a href="#cite_note-Duncan_1988_MS-DOS_Encyclopedia-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Chappell_1994_DOS-Internals_4-2" class="reference"><a href="#cite_note-Chappell_1994_DOS-Internals-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> than FAT or to share files<sup id="cite_ref-Chappell_1994_DOS-Internals_4-3" class="reference"><a href="#cite_note-Chappell_1994_DOS-Internals-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> over networks in the future, FCBs were felt to be too small to handle the extra data required for such features<sup id="cite_ref-Chappell_1994_DOS-Internals_4-4" class="reference"><a href="#cite_note-Chappell_1994_DOS-Internals-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> and therefore FCBs were seen as inadequate for various future expansion paths.<sup id="cite_ref-Duncan_1988_MS-DOS_Encyclopedia_3-3" class="reference"><a href="#cite_note-Duncan_1988_MS-DOS_Encyclopedia-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> Also, they didn't provide a field to specify sub-directories.<sup id="cite_ref-Duncan_1988_MS-DOS_Encyclopedia_3-4" class="reference"><a href="#cite_note-Duncan_1988_MS-DOS_Encyclopedia-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> Exposing file system related data to user-space was also seen as a security risk.<sup id="cite_ref-Chappell_1994_DOS-Internals_4-5" class="reference"><a href="#cite_note-Chappell_1994_DOS-Internals-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> FCBs were thus superseded by <a href="/wiki/File_handle" class="mw-redirect" title="File handle">file handles</a>, as used on <a href="/wiki/UNIX" class="mw-redirect" title="UNIX">UNIX</a> and its derivatives.<sup id="cite_ref-Duncan_1988_MS-DOS_Encyclopedia_3-5" class="reference"><a href="#cite_note-Duncan_1988_MS-DOS_Encyclopedia-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> File handles are simply consecutive integer numbers associated with specific open files. </p><p>If a program uses the newer file handle API to open a file, the operating system will manage its internal data structure associated with that file in its own memory area. This has the great advantage that these structures can grow in size in later operating system versions without breaking compatibility with application programs; its disadvantage is that, given the rather simplistic <a href="/wiki/Memory_management" title="Memory management">memory management</a> of DOS, space for as many of these structures as the most "file-hungry" program is likely to use has to be reserved at boot time and cannot be used for any other purpose while the computer is running. Such memory reservation is done using the <a href="/wiki/FILES_(CONFIG.SYS_directive)" class="mw-redirect" title="FILES (CONFIG.SYS directive)">FILES</a>= directive in the <a href="/wiki/CONFIG.SYS" title="CONFIG.SYS">CONFIG.SYS</a> file. This problem does not occur with FCBs in DOS 1 or in CP/M, since the operating system stores all that it needs to know about an open file inside the FCB and thus does not need to use any per-file memory in operating system memory space. When using FCBs in MS-DOS 3 or later, the FCB format depends on whether SHARE.EXE is loaded and whether the FCB refers to a local or remote file and often refers to a SFT entry. Because of this, the number of FCBs which can be kept open at once in DOS 3 or higher is limited as well, usually to 4; using the <a href="/wiki/FCBS_(CONFIG.SYS_directive)" class="mw-redirect" title="FCBS (CONFIG.SYS directive)">FCBS</a>= directive in the CONFIG.SYS file, it may be increased beyond that number if necessary. Under <a href="/wiki/DR-DOS" title="DR-DOS">DR-DOS</a>, both FILES and FCBS come from the same internal pool of available handles structures and are assigned dynamically as needed.<sup id="cite_ref-Paul_1997_NWDOSTIP_5-0" class="reference"><a href="#cite_note-Paul_1997_NWDOSTIP-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p><p>FCBs were supported in all versions of MS-DOS and <a href="/wiki/Microsoft_Windows" title="Microsoft Windows">Windows</a> until the introduction of the <a href="/wiki/FAT32" class="mw-redirect" title="FAT32">FAT32</a> filesystem. <a href="/wiki/Windows_95" title="Windows 95">Windows 95</a>, <a href="/wiki/Windows_98" title="Windows 98">Windows 98</a> and <a href="/wiki/Windows_Me" title="Windows Me">Windows Me</a> do not support the use of FCBs on FAT32 drives due to its 32-bit cluster numbers,<sup id="cite_ref-Chappell_1994_DOS-Internals_4-6" class="reference"><a href="#cite_note-Chappell_1994_DOS-Internals-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> except to read the volume label. This caused some old DOS applications, including <a href="/wiki/WordStar" title="WordStar">WordStar</a>, to fail under these versions of Windows. </p><p>The FCB interface does not work properly on <a href="/wiki/Windows_NT" title="Windows NT">Windows NT</a>, <a href="/wiki/Windows_2000" title="Windows 2000">2000</a>, etc. either – WordStar does not function properly on these operating systems. DOS emulators <a href="/wiki/DOSEMU" title="DOSEMU">DOSEMU</a> and <a href="/wiki/DOSBox" title="DOSBox">DOSBox</a> implement the FCB interface properly, thus they are a way to run older DOS programs that need FCBs on modern operating systems. </p> <div class="mw-heading mw-heading2"><h2 id="Disk_Transfer_Area">Disk Transfer Area</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=File_Control_Block&action=edit&section=2" title="Edit section: Disk Transfer Area"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>A companion data structure used together with the FCB was the <b>Disk Transfer Area</b> (DTA).<sup id="cite_ref-Programacion_Ensamblador_MSDOS_2-1" class="reference"><a href="#cite_note-Programacion_Ensamblador_MSDOS-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> This is the name given to the buffer where file contents (records) would be read into/written from. File access functions in DOS that used the FCB assumed a fixed location for the DTA, initially pointing to a part of the PSP (see next section); this location could be changed by calling a DOS function, with subsequent file accesses implicitly using the new location. </p><p>With the deprecation of the FCB method, the new file access functions which used file handles also provided a means to specify a memory buffer for file contents with every function call, such that maintaining concurrent, independent buffers (either for different files or for the same file) became much more practical. </p> <div class="mw-heading mw-heading2"><h2 id="Program_Segment_Prefix_&_Program_Initialisation"><span id="Program_Segment_Prefix_.26_Program_Initialisation"></span>Program Segment Prefix & Program Initialisation</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=File_Control_Block&action=edit&section=3" title="Edit section: Program Segment Prefix & Program Initialisation"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Every DOS executable started from the shell (<a href="/wiki/COMMAND.COM" title="COMMAND.COM">COMMAND.COM</a>) was provided with a pre-filled 256-byte long data structure called the <i><a href="/wiki/Program_Segment_Prefix" title="Program Segment Prefix">Program Segment Prefix</a></i> (PSP). Relevant fields within this structure include:<sup id="cite_ref-Programacion_Ensamblador_MSDOS_2-2" class="reference"><a href="#cite_note-Programacion_Ensamblador_MSDOS-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p> <table class="wikitable"> <tbody><tr> <th>Offset</th> <th>Byte<br />size</th> <th>Contents </th></tr> <tr> <td>0x02 </td> <td align="right">2</td> <td>Available memory for the program in 16-byte chunks. </td></tr> <tr> <td>0x2C </td> <td align="right">2</td> <td>Segment address containing the program's environment variables. </td></tr> <tr> <td>0x5C </td> <td align="right">16</td> <td>Prepared FCB for first command line argument (unopened). </td></tr> <tr> <td>0x6C </td> <td align="right">20</td> <td>Prepared FCB for second command line argument (unopened). </td></tr> <tr> <td>0x80 </td> <td align="right">1</td> <td>Length of command line. </td></tr> <tr> <td>0x81 </td> <td align="right">127</td> <td>Command line contents. </td></tr></tbody></table> <p>This data structure could be found at the beginning of the data segment whose address was provided by DOS at program start in the DS and ES segment registers. Besides providing the program's command line verbatim at address 0x81, DOS also tried to construct two FCB's corresponding to the first two words in the command line, the purpose being to save work for the programmer in the common case where these words were filenames to operate on. Since these FCB's remained unopened, no problem would ensue even if these command line words did not refer to files. </p><p>The initial address for the DTA was set to overlay the area in the PSP (at address 0x80) where the command line arguments were stored, such that a program needed to parse this area for command line arguments before invoking DOS functions that made use of the DTA (such as reading in a file record), unless the program took care to change the address of the DTA to some other memory region (or not use the DTA/FCB functions altogether, which soon became deprecated in favour of file handles). </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=File_Control_Block&action=edit&section=4" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Record-oriented_filesystem" title="Record-oriented filesystem">Record-oriented filesystem</a></li></ul> <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=File_Control_Block&action=edit&section=5" title="Edit section: References"><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"> <div class="mw-references-wrap"><ol class="references"> <li id="cite_note-stanislavs-1"><span class="mw-cite-backlink">^ <a href="#cite_ref-stanislavs_1-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-stanislavs_1-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-stanislavs_1-2"><sup><i><b>c</b></i></sup></a></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="http://stanislavs.org/helppc/fcb.html">"FCB - Standard DOS File Control Block"</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=FCB+-+Standard+DOS+File+Control+Block&rft_id=http%3A%2F%2Fstanislavs.org%2Fhelppc%2Ffcb.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AFile+Control+Block" class="Z3988"></span></span> </li> <li id="cite_note-Programacion_Ensamblador_MSDOS-2"><span class="mw-cite-backlink">^ <a href="#cite_ref-Programacion_Ensamblador_MSDOS_2-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Programacion_Ensamblador_MSDOS_2-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Programacion_Ensamblador_MSDOS_2-2"><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="CITEREFRodriguez-Rosello1992" class="citation book cs1 cs1-prop-foreign-lang-source">Rodriguez-Rosello, Miguel (1992). <i>8088-8086/8087 Programacion Ensamblador En Entorno MSDOS</i> (in Spanish). Ediciones Anaya Multimedia. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/84-7614-128-9" title="Special:BookSources/84-7614-128-9"><bdi>84-7614-128-9</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=8088-8086%2F8087+Programacion+Ensamblador+En+Entorno+MSDOS&rft.pub=Ediciones+Anaya+Multimedia&rft.date=1992&rft.isbn=84-7614-128-9&rft.aulast=Rodriguez-Rosello&rft.aufirst=Miguel&rfr_id=info%3Asid%2Fen.wikipedia.org%3AFile+Control+Block" class="Z3988"></span></span> </li> <li id="cite_note-Duncan_1988_MS-DOS_Encyclopedia-3"><span class="mw-cite-backlink">^ <a href="#cite_ref-Duncan_1988_MS-DOS_Encyclopedia_3-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Duncan_1988_MS-DOS_Encyclopedia_3-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Duncan_1988_MS-DOS_Encyclopedia_3-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-Duncan_1988_MS-DOS_Encyclopedia_3-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-Duncan_1988_MS-DOS_Encyclopedia_3-4"><sup><i><b>e</b></i></sup></a> <a href="#cite_ref-Duncan_1988_MS-DOS_Encyclopedia_3-5"><sup><i><b>f</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFZbikowskiAllenBallmerBorman1988" class="citation book cs1"><a href="/wiki/Mark_Zbikowski" title="Mark Zbikowski">Zbikowski, Mark</a>; <a href="/wiki/Paul_Allen" title="Paul Allen">Allen, Paul</a>; <a href="/wiki/Steve_Ballmer" title="Steve Ballmer">Ballmer, Steve</a>; Borman, Reuben; Borman, Rob; Butler, John; Carroll, Chuck; Chamberlain, Mark; Chell, David; Colee, Mike; Courtney, Mike; Dryfoos, Mike; Duncan, Rachel; Eckhardt, Kurt; Evans, Eric; Farmer, Rick; <a href="/wiki/Bill_Gates" title="Bill Gates">Gates, Bill</a>; Geary, Michael; Griffin, Bob; Hogarth, Doug; Johnson, James W.; Kermaani, Kaamel; King, Adrian; Koch, Reed; Landowski, James; Larson, Chris; Lennon, Thomas; Lipkie, Dan; <a href="/wiki/Marc_McDonald" title="Marc McDonald">McDonald, Marc</a>; McKinney, Bruce; Martin, Pascal; Mathers, Estelle; Matthews, Bob; Melin, David; Mergentime, Charles; Nevin, Randy; Newell, Dan; Newell, Tani; Norris, David; O'Leary, Mike; <a href="/wiki/Bob_O%27Rear" title="Bob O'Rear">O'Rear, Bob</a>; Olsson, Mike; Osterman, Larry; Ostling, Ridge; Pai, Sunil; <a href="/wiki/Tim_Paterson" title="Tim Paterson">Paterson, Tim</a>; Perez, Gary; Peters, Chris; <a href="/wiki/Charles_Petzold" title="Charles Petzold">Petzold, Charles</a>; Pollock, John; <a href="/wiki/Aaron_R._Reynolds" class="mw-redirect" title="Aaron R. Reynolds">Reynolds, Aaron</a>; Rubin, Darryl; Ryan, Ralph; Schulmeisters, Karl; Shah, Rajen; Shaw, Barry; Short, Anthony; Slivka, Ben; Smirl, Jon; Stillmaker, Betty; Stoddard, John; Tillman, Dennis; Whitten, Greg; Yount, Natalie; Zeck, Steve (1988). "Technical advisors". <i>The MS-DOS Encyclopedia: versions 1.0 through 3.2</i>. By Duncan, Ray; Bostwick, Steve; Burgoyne, Keith; Byers, Robert A.; Hogan, Thom; Kyle, Jim; <a href="/wiki/Gordon_Letwin" title="Gordon Letwin">Letwin, Gordon</a>; <a href="/wiki/Charles_Petzold" title="Charles Petzold">Petzold, Charles</a>; Rabinowitz, Chip; Tomlin, Jim; Wilton, Richard; Wolverton, Van; Wong, William; Woodcock, JoAnne (Completely reworked ed.). Redmond, Washington, USA: <a href="/wiki/Microsoft_Press" title="Microsoft Press">Microsoft Press</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/1-55615-049-0" title="Special:BookSources/1-55615-049-0"><bdi>1-55615-049-0</bdi></a>. <a href="/wiki/LCCN_(identifier)" class="mw-redirect" title="LCCN (identifier)">LCCN</a> <a rel="nofollow" class="external text" href="https://lccn.loc.gov/87-21452">87-21452</a>. <a href="/wiki/OCLC_(identifier)" class="mw-redirect" title="OCLC (identifier)">OCLC</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/oclc/16581341">16581341</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=Technical+advisors&rft.btitle=The+MS-DOS+Encyclopedia%3A+versions+1.0+through+3.2&rft.place=Redmond%2C+Washington%2C+USA&rft.edition=Completely+reworked&rft.pub=Microsoft+Press&rft.date=1988&rft_id=info%3Aoclcnum%2F16581341&rft_id=info%3Alccn%2F87-21452&rft.isbn=1-55615-049-0&rft.aulast=Zbikowski&rft.aufirst=Mark&rft.au=Allen%2C+Paul&rft.au=Ballmer%2C+Steve&rft.au=Borman%2C+Reuben&rft.au=Borman%2C+Rob&rft.au=Butler%2C+John&rft.au=Carroll%2C+Chuck&rft.au=Chamberlain%2C+Mark&rft.au=Chell%2C+David&rft.au=Colee%2C+Mike&rft.au=Courtney%2C+Mike&rft.au=Dryfoos%2C+Mike&rft.au=Duncan%2C+Rachel&rft.au=Eckhardt%2C+Kurt&rft.au=Evans%2C+Eric&rft.au=Farmer%2C+Rick&rft.au=Gates%2C+Bill&rft.au=Geary%2C+Michael&rft.au=Griffin%2C+Bob&rft.au=Hogarth%2C+Doug&rft.au=Johnson%2C+James+W.&rft.au=Kermaani%2C+Kaamel&rft.au=King%2C+Adrian&rft.au=Koch%2C+Reed&rft.au=Landowski%2C+James&rft.au=Larson%2C+Chris&rft.au=Lennon%2C+Thomas&rft.au=Lipkie%2C+Dan&rft.au=McDonald%2C+Marc&rft.au=McKinney%2C+Bruce&rft.au=Martin%2C+Pascal&rft.au=Mathers%2C+Estelle&rft.au=Matthews%2C+Bob&rft.au=Melin%2C+David&rft.au=Mergentime%2C+Charles&rft.au=Nevin%2C+Randy&rft.au=Newell%2C+Dan&rft.au=Newell%2C+Tani&rft.au=Norris%2C+David&rft.au=O%27Leary%2C+Mike&rft.au=O%27Rear%2C+Bob&rft.au=Olsson%2C+Mike&rft.au=Osterman%2C+Larry&rft.au=Ostling%2C+Ridge&rft.au=Pai%2C+Sunil&rft.au=Paterson%2C+Tim&rft.au=Perez%2C+Gary&rft.au=Peters%2C+Chris&rft.au=Petzold%2C+Charles&rft.au=Pollock%2C+John&rft.au=Reynolds%2C+Aaron&rft.au=Rubin%2C+Darryl&rft.au=Ryan%2C+Ralph&rft.au=Schulmeisters%2C+Karl&rft.au=Shah%2C+Rajen&rft.au=Shaw%2C+Barry&rft.au=Short%2C+Anthony&rft.au=Slivka%2C+Ben&rft.au=Smirl%2C+Jon&rft.au=Stillmaker%2C+Betty&rft.au=Stoddard%2C+John&rft.au=Tillman%2C+Dennis&rft.au=Whitten%2C+Greg&rft.au=Yount%2C+Natalie&rft.au=Zeck%2C+Steve&rfr_id=info%3Asid%2Fen.wikipedia.org%3AFile+Control+Block" class="Z3988"></span> (xix+1570 pages; 26 cm) (NB. This edition was published in 1988 after extensive rework of the withdrawn 1986 first edition by a different team of authors. <a rel="nofollow" class="external autonumber" href="https://www.pcjs.org/pubs/pc/reference/microsoft/mspl13/msdos/encyclopedia/">[1]</a>)</span> </li> <li id="cite_note-Chappell_1994_DOS-Internals-4"><span class="mw-cite-backlink">^ <a href="#cite_ref-Chappell_1994_DOS-Internals_4-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Chappell_1994_DOS-Internals_4-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Chappell_1994_DOS-Internals_4-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-Chappell_1994_DOS-Internals_4-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-Chappell_1994_DOS-Internals_4-4"><sup><i><b>e</b></i></sup></a> <a href="#cite_ref-Chappell_1994_DOS-Internals_4-5"><sup><i><b>f</b></i></sup></a> <a href="#cite_ref-Chappell_1994_DOS-Internals_4-6"><sup><i><b>g</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFChappell1994" class="citation book cs1">Chappell, Geoff (January 1994). Schulman, Andrew; Pedersen, Amorette (eds.). <i>DOS Internals</i>. The Andrew Schulman Programming Series (1st printing, 1st ed.). <a href="/wiki/Addison_Wesley_Publishing_Company" class="mw-redirect" title="Addison Wesley Publishing Company">Addison Wesley Publishing Company</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-201-60835-9" title="Special:BookSources/978-0-201-60835-9"><bdi>978-0-201-60835-9</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=DOS+Internals&rft.series=The+Andrew+Schulman+Programming+Series&rft.edition=1st+printing%2C+1st&rft.pub=Addison+Wesley+Publishing+Company&rft.date=1994-01&rft.isbn=978-0-201-60835-9&rft.aulast=Chappell&rft.aufirst=Geoff&rfr_id=info%3Asid%2Fen.wikipedia.org%3AFile+Control+Block" class="Z3988"></span> (xxvi+738+iv pages, 3.5"-floppy <a rel="nofollow" class="external autonumber" href="https://web.archive.org/web/20190421200111/https://gopher.tildeverse.org/gopher.viste.fr/9/programming/PC/DOS/DOS%2520Internals/DOS_Internals.zip">[2]</a><a rel="nofollow" class="external autonumber" href="https://web.archive.org/web/20200222111608/https://www.pcjs.org/pubs/pc/programming/DOS_Internals/">[3]</a>) Errata: <a rel="nofollow" class="external autonumber" href="https://web.archive.org/web/20200222111742/http://www.geoffchappell.com/notes/dos/internals/">[4]</a><a rel="nofollow" class="external autonumber" href="https://web.archive.org/web/20200222111853/https://gopher.tildeverse.org/gopher.viste.fr/1/programming/PC/DOS/DOS%2520Internals/crtdrvr">[5]</a><a rel="nofollow" class="external autonumber" href="https://web.archive.org/web/20200222111945/https://gopher.tildeverse.org/gopher.viste.fr/1/programming/PC/DOS/DOS%2520Internals/xmswatch">[6]</a></span> </li> <li id="cite_note-Paul_1997_NWDOSTIP-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-Paul_1997_NWDOSTIP_5-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFPaul1997" class="citation book cs1 cs1-prop-foreign-lang-source">Paul, Matthias R. (1997-07-30). <a rel="nofollow" class="external text" href="http://www.antonis.de/dos/dos-tuts/mpdostip/html/nwdostip.htm"><i>NWDOS-TIPs — Tips & Tricks rund um Novell DOS 7, mit Blick auf undokumentierte Details, Bugs und Workarounds</i></a>. Release 157 (in German) (3 ed.). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20170823014801/http://www.antonis.de/dos/dos-tuts/mpdostip/html/nwdostip.htm">Archived</a> from the original on 2017-08-23<span class="reference-accessdate">. Retrieved <span class="nowrap">2012-01-11</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=NWDOS-TIPs+%26mdash%3B+Tips+%26+Tricks+rund+um+Novell+DOS+7%2C+mit+Blick+auf+undokumentierte+Details%2C+Bugs+und+Workarounds&rft.series=Release+157&rft.edition=3&rft.date=1997-07-30&rft.aulast=Paul&rft.aufirst=Matthias+R.&rft_id=http%3A%2F%2Fwww.antonis.de%2Fdos%2Fdos-tuts%2Fmpdostip%2Fhtml%2Fnwdostip.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3AFile+Control+Block" class="Z3988"></span> <span class="cs1-visible-error citation-comment"><code class="cs1-code">{{<a href="/wiki/Template:Cite_book" title="Template:Cite book">cite book</a>}}</code>: </span><span class="cs1-visible-error citation-comment"><code class="cs1-code">|work=</code> ignored (<a href="/wiki/Help:CS1_errors#periodical_ignored" title="Help:CS1 errors">help</a>)</span> (NB. NWDOSTIP.TXT is a comprehensive work on <a href="/wiki/Novell_DOS_7" class="mw-redirect" title="Novell DOS 7">Novell DOS 7</a> and <a href="/wiki/OpenDOS_7.01" class="mw-redirect" title="OpenDOS 7.01">OpenDOS 7.01</a>, including the description of many undocumented features and internals. It is part of the author's yet larger MPDOSTIP.ZIP collection maintained up to 2001 and distributed on many sites at the time. The provided link points to a HTML-converted older version of the NWDOSTIP.TXT file.)</span> </li> </ol></div></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=File_Control_Block&action=edit&section=6" 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 id="CITEREFBrown2000" class="citation web cs1"><a href="/wiki/Ralf_D._Brown" class="mw-redirect" title="Ralf D. Brown">Brown, Ralf D.</a>, ed. (2000-07-17). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20160619060655/http://www.ctyme.com/intr/rb-2574.htm">"210F: DOS 1+ - OPEN FILE USING FCB"</a>. <i><a href="/wiki/Ralf_Brown%27s_Interrupt_List" title="Ralf Brown's Interrupt List">Ralf Brown's Interrupt List</a> 61</i>. ctyme.com. Archived from <a rel="nofollow" class="external text" href="http://www.ctyme.com/intr/rb-2574.htm">the original</a> on 2016-06-19.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Ralf+Brown%27s+Interrupt+List+61&rft.atitle=210F%3A+DOS+1%2B+-+OPEN+FILE+USING+FCB&rft.date=2000-07-17&rft_id=http%3A%2F%2Fwww.ctyme.com%2Fintr%2Frb-2574.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3AFile+Control+Block" class="Z3988"></span> <a rel="nofollow" class="external autonumber" href="http://www.delorie.com/djgpp/doc/rbinter/id/85/25.html">[7]</a></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFElliott2002" class="citation web cs1">Elliott, John C. (2002-12-29). <a rel="nofollow" class="external text" href="http://seasip.info/Cpm/fcb.html">"CP/M File Control Block"</a>. <i>Seasip.info</i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20170823020604/http://seasip.info/Cpm/fcb.html">Archived</a> from the original on 2017-08-23<span class="reference-accessdate">. Retrieved <span class="nowrap">2017-08-23</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Seasip.info&rft.atitle=CP%2FM+File+Control+Block&rft.date=2002-12-29&rft.aulast=Elliott&rft.aufirst=John+C.&rft_id=http%3A%2F%2Fseasip.info%2FCpm%2Ffcb.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AFile+Control+Block" 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/20170823015253/http://obsolescence.wixsite.com/obsolescence/cpm-internals?_escaped_fragment_=cpm-internals%2Fc247i#!cpm-internals/c247i">"CP/M Internals"</a>. 2017-08-23. Archived from <a rel="nofollow" class="external text" href="http://obsolescence.wix.com/obsolescence#!cpm-internals/c247i">the original</a> on 2017-08-23<span class="reference-accessdate">. Retrieved <span class="nowrap">2017-08-23</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=CP%2FM+Internals&rft.date=2017-08-23&rft_id=http%3A%2F%2Fobsolescence.wix.com%2Fobsolescence%23%21cpm-internals%2Fc247i&rfr_id=info%3Asid%2Fen.wikipedia.org%3AFile+Control+Block" class="Z3988"></span> - In-depth description of CP/M FCB</li></ul> <div class="navbox-styles"><style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist ul{margin:0;padding:0}.mw-parser-output .hlist dd,.mw-parser-output .hlist dt,.mw-parser-output .hlist li{margin:0;display:inline}.mw-parser-output .hlist.inline,.mw-parser-output .hlist.inline dl,.mw-parser-output .hlist.inline ol,.mw-parser-output .hlist.inline ul,.mw-parser-output .hlist dl dl,.mw-parser-output .hlist dl ol,.mw-parser-output .hlist dl ul,.mw-parser-output .hlist ol dl,.mw-parser-output .hlist ol ol,.mw-parser-output .hlist ol ul,.mw-parser-output .hlist ul dl,.mw-parser-output .hlist ul ol,.mw-parser-output .hlist ul ul{display:inline}.mw-parser-output .hlist .mw-empty-li{display:none}.mw-parser-output .hlist dt::after{content:": "}.mw-parser-output .hlist dd::after,.mw-parser-output .hlist li::after{content:" · ";font-weight:bold}.mw-parser-output .hlist dd:last-child::after,.mw-parser-output .hlist dt:last-child::after,.mw-parser-output .hlist li:last-child::after{content:none}.mw-parser-output .hlist dd dd:first-child::before,.mw-parser-output .hlist dd dt:first-child::before,.mw-parser-output .hlist dd li:first-child::before,.mw-parser-output .hlist dt dd:first-child::before,.mw-parser-output .hlist dt dt:first-child::before,.mw-parser-output .hlist dt li:first-child::before,.mw-parser-output .hlist li dd:first-child::before,.mw-parser-output .hlist li dt:first-child::before,.mw-parser-output .hlist li li:first-child::before{content:" (";font-weight:normal}.mw-parser-output .hlist dd dd:last-child::after,.mw-parser-output .hlist dd dt:last-child::after,.mw-parser-output .hlist dd li:last-child::after,.mw-parser-output .hlist dt dd:last-child::after,.mw-parser-output .hlist dt dt:last-child::after,.mw-parser-output .hlist dt li:last-child::after,.mw-parser-output .hlist li dd:last-child::after,.mw-parser-output .hlist li dt:last-child::after,.mw-parser-output .hlist li li:last-child::after{content:")";font-weight:normal}.mw-parser-output .hlist ol{counter-reset:listitem}.mw-parser-output .hlist ol>li{counter-increment:listitem}.mw-parser-output .hlist ol>li::before{content:" "counter(listitem)"\a0 "}.mw-parser-output .hlist dd ol>li:first-child::before,.mw-parser-output .hlist dt ol>li:first-child::before,.mw-parser-output .hlist li ol>li:first-child::before{content:" ("counter(listitem)"\a0 "}</style><style data-mw-deduplicate="TemplateStyles:r1236075235">.mw-parser-output .navbox{box-sizing:border-box;border:1px solid #a2a9b1;width:100%;clear:both;font-size:88%;text-align:center;padding:1px;margin:1em auto 0}.mw-parser-output .navbox .navbox{margin-top:0}.mw-parser-output .navbox+.navbox,.mw-parser-output .navbox+.navbox-styles+.navbox{margin-top:-1px}.mw-parser-output .navbox-inner,.mw-parser-output .navbox-subgroup{width:100%}.mw-parser-output .navbox-group,.mw-parser-output .navbox-title,.mw-parser-output .navbox-abovebelow{padding:0.25em 1em;line-height:1.5em;text-align:center}.mw-parser-output .navbox-group{white-space:nowrap;text-align:right}.mw-parser-output .navbox,.mw-parser-output .navbox-subgroup{background-color:#fdfdfd}.mw-parser-output .navbox-list{line-height:1.5em;border-color:#fdfdfd}.mw-parser-output .navbox-list-with-group{text-align:left;border-left-width:2px;border-left-style:solid}.mw-parser-output tr+tr>.navbox-abovebelow,.mw-parser-output tr+tr>.navbox-group,.mw-parser-output tr+tr>.navbox-image,.mw-parser-output tr+tr>.navbox-list{border-top:2px solid #fdfdfd}.mw-parser-output .navbox-title{background-color:#ccf}.mw-parser-output .navbox-abovebelow,.mw-parser-output .navbox-group,.mw-parser-output .navbox-subgroup .navbox-title{background-color:#ddf}.mw-parser-output .navbox-subgroup .navbox-group,.mw-parser-output .navbox-subgroup .navbox-abovebelow{background-color:#e6e6ff}.mw-parser-output .navbox-even{background-color:#f7f7f7}.mw-parser-output .navbox-odd{background-color:transparent}.mw-parser-output .navbox .hlist td dl,.mw-parser-output .navbox .hlist td ol,.mw-parser-output .navbox .hlist td ul,.mw-parser-output .navbox td.hlist dl,.mw-parser-output .navbox td.hlist ol,.mw-parser-output .navbox td.hlist ul{padding:0.125em 0}.mw-parser-output .navbox .navbar{display:block;font-size:100%}.mw-parser-output .navbox-title .navbar{float:left;text-align:left;margin-right:0.5em}body.skin--responsive .mw-parser-output .navbox-image img{max-width:none!important}@media print{body.ns-0 .mw-parser-output .navbox{display:none!important}}</style></div><div role="navigation" class="navbox" aria-labelledby="Digital_Research" style="padding:3px"><table class="nowraplinks mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="3"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><style data-mw-deduplicate="TemplateStyles:r1239400231">.mw-parser-output .navbar{display:inline;font-size:88%;font-weight:normal}.mw-parser-output .navbar-collapse{float:left;text-align:left}.mw-parser-output .navbar-boxtext{word-spacing:0}.mw-parser-output .navbar ul{display:inline-block;white-space:nowrap;line-height:inherit}.mw-parser-output .navbar-brackets::before{margin-right:-0.125em;content:"[ "}.mw-parser-output .navbar-brackets::after{margin-left:-0.125em;content:" ]"}.mw-parser-output .navbar li{word-spacing:-0.125em}.mw-parser-output .navbar a>span,.mw-parser-output .navbar a>abbr{text-decoration:inherit}.mw-parser-output .navbar-mini abbr{font-variant:small-caps;border-bottom:none;text-decoration:none;cursor:inherit}.mw-parser-output .navbar-ct-full{font-size:114%;margin:0 7em}.mw-parser-output .navbar-ct-mini{font-size:114%;margin:0 4em}html.skin-theme-clientpref-night .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}@media(prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}}@media print{.mw-parser-output .navbar{display:none!important}}</style><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Digital_Research" title="Template:Digital Research"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Digital_Research" title="Template talk:Digital Research"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Digital_Research" title="Special:EditPage/Template:Digital Research"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Digital_Research" style="font-size:114%;margin:0 4em"><a href="/wiki/Digital_Research" title="Digital Research">Digital Research</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">People</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><a href="/wiki/Gary_Kildall" title="Gary Kildall">Gary Kildall</a></li> <li><a href="/wiki/Dorothy_McEwen_Kildall" title="Dorothy McEwen Kildall">Dorothy McEwen Kildall</a></li> <li><a href="/wiki/Gordon_Eubanks" title="Gordon Eubanks">Gordon Eubanks</a></li> <li><a href="/wiki/Tom_Rolander" title="Tom Rolander">Tom Rolander</a></li> <li><a href="/wiki/Kathryn_Strutynski" title="Kathryn Strutynski">Kathryn Strutynski</a></li> <li><a href="/wiki/Edward_R._McCracken" title="Edward R. McCracken">Edward R. McCracken</a></li></ul> </div></td><td class="noviewer navbox-image" rowspan="3" style="width:1px;padding:0 0 0 2px"><div><span class="mw-default-size" typeof="mw:File/Frameless"><a href="/wiki/File:Digital_Research_Logo.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/1/16/Digital_Research_Logo.svg/110px-Digital_Research_Logo.svg.png" decoding="async" width="110" height="38" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/16/Digital_Research_Logo.svg/165px-Digital_Research_Logo.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/16/Digital_Research_Logo.svg/220px-Digital_Research_Logo.svg.png 2x" data-file-width="2869" data-file-height="1000" /></a></span></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Products</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%"><a href="/wiki/Programming_language" title="Programming language">Programming<br />languages</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/PL/M" title="PL/M">PL/M</a></li> <li><a href="/wiki/CBASIC" title="CBASIC">CBASIC</a></li> <li><a href="/wiki/Dr._Logo" class="mw-redirect" title="Dr. Logo">Dr. Logo</a></li> <li><a href="/wiki/Dr._Scheme" class="mw-redirect" title="Dr. Scheme">Dr. Scheme</a></li> <li><a href="/wiki/Atari_Pascal" title="Atari Pascal">Atari Pascal</a></li> <li><a href="/wiki/Pascal/MT%2B" title="Pascal/MT+">Pascal/MT+</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Software" title="Software">Software</a>,<br />technology</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/BatteryMAX" title="BatteryMAX">BatteryMAX</a></li> <li><a href="/wiki/CMD_file_(CP/M)" title="CMD file (CP/M)">CMD file</a></li> <li><a href="/wiki/COM_file" title="COM file">COM file</a></li> <li><a href="/wiki/DOS_Protected_Mode_Services" title="DOS Protected Mode Services">DOS Protected Mode Services</a></li> <li><a href="/wiki/Dynamic_debugging_technique" title="Dynamic debugging technique">Dynamic Debugging Tool</a></li> <li><a class="mw-selflink selflink">File Control Block</a></li> <li><a href="/wiki/Graphics_Environment_Manager" class="mw-redirect" title="Graphics Environment Manager">GEM</a> <ul><li><a href="/wiki/GEM_character_set" title="GEM character set">GEM character set</a></li></ul></li> <li><a href="/wiki/Peripheral_Interchange_Program" title="Peripheral Interchange Program">Peripheral Interchange Program</a></li> <li><a href="/wiki/Resource_construction_set" title="Resource construction set">Resource construction set</a></li> <li><a href="/wiki/ViewMAX" title="ViewMAX">ViewMAX</a></li> <li><a href="/wiki/XLT86" class="mw-redirect" title="XLT86">XLT86</a></li> <li><a href="/wiki/Zero_page_(CP/M)" title="Zero page (CP/M)">Zero page</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Operating_system" title="Operating system">Operating systems</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/CP/M" title="CP/M">CP/M</a></li> <li><a href="/wiki/CP/M-86" title="CP/M-86">CP/M-86</a></li> <li><a href="/wiki/DOS_Plus" title="DOS Plus">DOS Plus</a></li> <li><a href="/wiki/DR-DOS" title="DR-DOS">DR-DOS</a></li> <li><a href="/wiki/FlexOS" title="FlexOS">FlexOS</a></li> <li><a href="/wiki/IMDOS" title="IMDOS">IMDOS</a></li> <li><a href="/wiki/MP/M" title="MP/M">MP/M</a></li> <li><a href="/wiki/Multiuser_DOS" title="Multiuser DOS">Multiuser DOS</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Related</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><a href="/wiki/CPMulator" title="CPMulator">CPMulator</a></li> <li><a href="/wiki/Star_Trek_project" title="Star Trek project">Star Trek project</a></li> <li><a href="/wiki/List_of_computers_running_CP/M" title="List of computers running CP/M">List of computers running CP/M</a></li></ul> </div></td></tr><tr><td class="navbox-abovebelow" colspan="3"><div><span class="noviewer" typeof="mw:File"><span title="Category"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/16px-Symbol_category_class.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/23px-Symbol_category_class.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/31px-Symbol_category_class.svg.png 2x" data-file-width="180" data-file-height="185" /></span></span> <a href="/wiki/Category:Digital_Research" title="Category:Digital Research">Category</a></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=File_Control_Block&oldid=1116761064">https://en.wikipedia.org/w/index.php?title=File_Control_Block&oldid=1116761064</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:Disk_file_systems" title="Category:Disk file systems">Disk file systems</a></li><li><a href="/wiki/Category:CP/M_technology" title="Category:CP/M technology">CP/M technology</a></li><li><a href="/wiki/Category:DOS_technology" title="Category:DOS technology">DOS technology</a></li></ul></div><div id="mw-hidden-catlinks" class="mw-hidden-catlinks mw-hidden-cats-hidden">Hidden categories: <ul><li><a href="/wiki/Category:CS1_Spanish-language_sources_(es)" title="Category:CS1 Spanish-language sources (es)">CS1 Spanish-language sources (es)</a></li><li><a href="/wiki/Category:CS1_errors:_periodical_ignored" title="Category:CS1 errors: periodical ignored">CS1 errors: periodical ignored</a></li><li><a href="/wiki/Category:CS1_German-language_sources_(de)" title="Category:CS1 German-language sources (de)">CS1 German-language sources (de)</a></li><li><a href="/wiki/Category:Articles_needing_additional_references_from_January_2014" title="Category:Articles needing additional references from January 2014">Articles needing additional references from January 2014</a></li><li><a href="/wiki/Category:All_articles_needing_additional_references" title="Category:All articles needing additional references">All articles needing additional references</a></li><li><a href="/wiki/Category:Wikipedia_articles_that_are_too_technical_from_October_2022" title="Category:Wikipedia articles that are too technical from October 2022">Wikipedia articles that are too technical from October 2022</a></li><li><a href="/wiki/Category:All_articles_that_are_too_technical" title="Category:All articles that are too technical">All articles that are too technical</a></li><li><a href="/wiki/Category:Articles_with_multiple_maintenance_issues" title="Category:Articles with multiple maintenance issues">Articles with multiple maintenance issues</a></li><li><a href="/wiki/Category:Use_dmy_dates_from_May_2019" title="Category:Use dmy dates from May 2019">Use dmy dates from May 2019</a></li></ul></div></div> </div> </main> </div> <div class="mw-footer-container"> <footer id="footer" class="mw-footer" > <ul id="footer-info"> <li id="footer-info-lastmod"> This page was last edited on 18 October 2022, at 05:49<span class="anonymous-show"> (UTC)</span>.</li> <li id="footer-info-copyright">Text is available under the <a href="/wiki/Wikipedia:Text_of_the_Creative_Commons_Attribution-ShareAlike_4.0_International_License" title="Wikipedia:Text of the Creative Commons Attribution-ShareAlike 4.0 International License">Creative Commons Attribution-ShareAlike 4.0 License</a>; additional terms may apply. By using this site, you agree to the <a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Terms_of_Use" class="extiw" title="foundation:Special:MyLanguage/Policy:Terms of Use">Terms of Use</a> and <a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Privacy_policy" class="extiw" title="foundation:Special:MyLanguage/Policy:Privacy policy">Privacy Policy</a>. Wikipedia® is a registered trademark of the <a rel="nofollow" class="external text" href="https://wikimediafoundation.org/">Wikimedia Foundation, Inc.</a>, a non-profit organization.</li> </ul> <ul id="footer-places"> <li id="footer-places-privacy"><a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Privacy_policy">Privacy policy</a></li> <li id="footer-places-about"><a href="/wiki/Wikipedia:About">About Wikipedia</a></li> <li id="footer-places-disclaimers"><a href="/wiki/Wikipedia:General_disclaimer">Disclaimers</a></li> <li id="footer-places-contact"><a href="//en.wikipedia.org/wiki/Wikipedia:Contact_us">Contact Wikipedia</a></li> <li id="footer-places-wm-codeofconduct"><a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Universal_Code_of_Conduct">Code of Conduct</a></li> <li id="footer-places-developers"><a href="https://developer.wikimedia.org">Developers</a></li> <li id="footer-places-statslink"><a href="https://stats.wikimedia.org/#/en.wikipedia.org">Statistics</a></li> <li id="footer-places-cookiestatement"><a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Cookie_statement">Cookie statement</a></li> <li id="footer-places-mobileview"><a href="//en.m.wikipedia.org/w/index.php?title=File_Control_Block&mobileaction=toggle_view_mobile" class="noprint stopMobileRedirectToggle">Mobile view</a></li> </ul> <ul id="footer-icons" class="noprint"> <li id="footer-copyrightico"><a href="https://wikimediafoundation.org/" class="cdx-button cdx-button--fake-button cdx-button--size-large cdx-button--fake-button--enabled"><img src="/static/images/footer/wikimedia-button.svg" width="84" height="29" alt="Wikimedia Foundation" loading="lazy"></a></li> <li id="footer-poweredbyico"><a href="https://www.mediawiki.org/" class="cdx-button cdx-button--fake-button cdx-button--size-large cdx-button--fake-button--enabled"><img src="/w/resources/assets/poweredby_mediawiki.svg" alt="Powered by MediaWiki" width="88" height="31" loading="lazy"></a></li> </ul> </footer> </div> </div> </div> <div class="vector-settings" id="p-dock-bottom"> <ul></ul> </div><script>(RLQ=window.RLQ||[]).push(function(){mw.config.set({"wgHostname":"mw-web.codfw.main-5cd4cd96d5-8ccf9","wgBackendResponseTime":193,"wgPageParseReport":{"limitreport":{"cputime":"0.382","walltime":"0.477","ppvisitednodes":{"value":1356,"limit":1000000},"postexpandincludesize":{"value":64254,"limit":2097152},"templateargumentsize":{"value":8643,"limit":2097152},"expansiondepth":{"value":14,"limit":100},"expensivefunctioncount":{"value":4,"limit":500},"unstrip-depth":{"value":1,"limit":20},"unstrip-size":{"value":48806,"limit":5000000},"entityaccesscount":{"value":0,"limit":400},"timingprofile":["100.00% 421.831 1 -total"," 36.66% 154.658 1 Template:Reflist"," 27.45% 115.774 1 Template:Multiple_issues"," 25.69% 108.360 1 Template:Digital_Research"," 24.56% 103.582 2 Template:Navbox"," 21.50% 90.701 4 Template:Cite_web"," 14.77% 62.294 1 Template:Refimprove"," 14.59% 61.543 2 Template:Ambox"," 12.26% 51.700 4 Template:Cite_book"," 4.49% 18.960 1 Template:Use_dmy_dates"]},"scribunto":{"limitreport-timeusage":{"value":"0.257","limit":"10.000"},"limitreport-memusage":{"value":5198397,"limit":52428800}},"cachereport":{"origin":"mw-web.eqiad.main-559c9fd9f4-xjmlf","timestamp":"20241126133127","ttl":2592000,"transientcontent":false}}});});</script> <script type="application/ld+json">{"@context":"https:\/\/schema.org","@type":"Article","name":"File Control Block","url":"https:\/\/en.wikipedia.org\/wiki\/File_Control_Block","sameAs":"http:\/\/www.wikidata.org\/entity\/Q1412592","mainEntity":"http:\/\/www.wikidata.org\/entity\/Q1412592","author":{"@type":"Organization","name":"Contributors to Wikimedia projects"},"publisher":{"@type":"Organization","name":"Wikimedia Foundation, Inc.","logo":{"@type":"ImageObject","url":"https:\/\/www.wikimedia.org\/static\/images\/wmf-hor-googpub.png"}},"datePublished":"2004-12-12T12:30:14Z","dateModified":"2022-10-18T05:49:52Z","headline":"data structure used for file access in CP\/M, MS-DOS and compatible operating systems"}</script> </body> </html>