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noexcerpt noprint searchaux" style="display:none">Flow control method</div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">"Xon" redirects here; not to be confused with <a href="/wiki/Xon_(character)" class="mw-redirect" title="Xon (character)">Xon (character)</a> or <a href="/wiki/XON_(company)" class="mw-redirect" title="XON (company)">XON (company)</a>.</div> <style data-mw-deduplicate="TemplateStyles:r1251242444">.mw-parser-output .ambox{border:1px solid #a2a9b1;border-left:10px solid #36c;background-color:#fbfbfb;box-sizing:border-box}.mw-parser-output .ambox+link+.ambox,.mw-parser-output .ambox+link+style+.ambox,.mw-parser-output .ambox+link+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+style+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+link+.ambox{margin-top:-1px}html body.mediawiki .mw-parser-output .ambox.mbox-small-left{margin:4px 1em 4px 0;overflow:hidden;width:238px;border-collapse:collapse;font-size:88%;line-height:1.25em}.mw-parser-output .ambox-speedy{border-left:10px solid #b32424;background-color:#fee7e6}.mw-parser-output .ambox-delete{border-left:10px solid #b32424}.mw-parser-output .ambox-content{border-left:10px solid #f28500}.mw-parser-output .ambox-style{border-left:10px solid #fc3}.mw-parser-output .ambox-move{border-left:10px solid #9932cc}.mw-parser-output .ambox-protection{border-left:10px solid #a2a9b1}.mw-parser-output .ambox .mbox-text{border:none;padding:0.25em 0.5em;width:100%}.mw-parser-output .ambox .mbox-image{border:none;padding:2px 0 2px 0.5em;text-align:center}.mw-parser-output .ambox .mbox-imageright{border:none;padding:2px 0.5em 2px 0;text-align:center}.mw-parser-output .ambox .mbox-empty-cell{border:none;padding:0;width:1px}.mw-parser-output .ambox .mbox-image-div{width:52px}@media(min-width:720px){.mw-parser-output .ambox{margin:0 10%}}@media print{body.ns-0 .mw-parser-output .ambox{display:none!important}}</style><table class="box-More_citations_needed 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/Software_flow_control" title="Special:EditPage/Software flow control">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=%22Software+flow+control%22">"Software flow control"</a> – <a rel="nofollow" class="external text" href="https://www.google.com/search?tbm=nws&q=%22Software+flow+control%22+-wikipedia&tbs=ar:1">news</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.google.com/search?&q=%22Software+flow+control%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=%22Software+flow+control%22+-wikipedia">books</a> <b>·</b> <a rel="nofollow" class="external text" href="https://scholar.google.com/scholar?q=%22Software+flow+control%22">scholar</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.jstor.org/action/doBasicSearch?Query=%22Software+flow+control%22&acc=on&wc=on">JSTOR</a></span></small></span> <span class="date-container"><i>(<span class="date">March 2009</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> <p><b>Software flow control</b> is a method of <a href="/wiki/Flow_control_(data)" title="Flow control (data)">flow control</a> used in computer <a href="/wiki/Data_link" title="Data link">data links</a>, especially <a href="/wiki/RS-232" title="RS-232">RS-232 serial</a>. It uses special codes, transmitted <a href="/wiki/In-band_signaling" title="In-band signaling">in-band</a>, over the primary communications channel. These codes are generally called <b>XOFF</b> and <b>XON</b> (from "transmit off" and "transmit on", respectively). Thus, "software flow control" is sometimes called "XON/XOFF flow control". This is in contrast to flow control via dedicated <a href="/wiki/Out-of-band_data" title="Out-of-band data">out-of-band</a> signals — "<a href="/wiki/Flow_control_(data)#Hardware_flow_control" title="Flow control (data)">hardware flow control</a>" — such as <a href="/wiki/RS-232_RTS/CTS" class="mw-redirect" title="RS-232 RTS/CTS">RS-232 RTS/CTS</a>. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Representation">Representation</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Software_flow_control&action=edit&section=1" title="Edit section: Representation"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>For systems using the <a href="/wiki/ASCII" title="ASCII">ASCII</a> character code, XOFF is generally represented using a <a href="/wiki/Character_(computing)" title="Character (computing)">character</a> or <a href="/wiki/Byte" title="Byte">byte</a> with decimal value 19; XON with value 17. </p><p>The ASCII standard does not reserve any <a href="/wiki/Control_character" title="Control character">control characters</a> for use as XON/XOFF specifically. However, it does provide four generic "device control" characters (DC1 through DC4). The <a href="/wiki/Teletype_Model_33" title="Teletype Model 33">Teletype Model 33</a> ASR adopted two of these, DC3 and DC1, for use as XOFF and XON, respectively. This usage was copied by others, and is now a <a href="/wiki/De_facto_standard" title="De facto standard">de facto standard</a>. The keyboard equivalents of <style data-mw-deduplicate="TemplateStyles:r1249182868">.mw-parser-output .keyboard-key{border:1px solid #aaa;border-radius:0.2em;box-shadow:0.1em 0.1em 0.2em rgba(0,0,0,0.1);background-color:var(--background-color-neutral-subtle,#f8f9fa);background-image:linear-gradient(to bottom,var(--background-color-neutral,#eaecf0),var(--background-color-neutral-subtle,#f8f9fa),var(--background-color-neutral,#eaecf0));color:var(--color-base,#202122);padding:0.1em 0.3em;font-family:inherit;font-size:0.85em}</style><kbd class="keyboard-key nowrap">Ctrl</kbd>+<kbd class="keyboard-key nowrap">S</kbd> for XOFF, and <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1249182868" /><kbd class="keyboard-key nowrap">Ctrl</kbd>+<kbd class="keyboard-key nowrap">Q</kbd> for XON, also derive from this usage. </p> <table class="wikitable"> <caption>XOFF/XON representations in ASCII </caption> <tbody><tr> <th>Code </th> <th>Meaning </th> <th><a href="/wiki/ASCII" title="ASCII">ASCII</a> </th> <th><a href="/wiki/Decimal" title="Decimal">Dec</a> </th> <th><a href="/wiki/Hexadecimal" title="Hexadecimal">Hex</a> </th> <th>Keyboard </th></tr> <tr> <td>XOFF </td> <td>Pause transmission </td> <td>DC3 </td> <td>19 </td> <td>13 </td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1249182868" /><kbd class="keyboard-key nowrap">Ctrl</kbd>+<kbd class="keyboard-key nowrap">S</kbd> </td></tr> <tr> <td>XON </td> <td>Resume transmission </td> <td>DC1 </td> <td>17 </td> <td>11 </td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1249182868" /><kbd class="keyboard-key nowrap">Ctrl</kbd>+<kbd class="keyboard-key nowrap">Q</kbd> </td></tr></tbody></table> <div class="mw-heading mw-heading2"><h2 id="Mechanism">Mechanism</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Software_flow_control&action=edit&section=2" title="Edit section: Mechanism"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>When one end of a data link is unable to accept any more data (or approaching that point), it sends XOFF to the other end. The other end receives the XOFF code, and suspends <a href="/wiki/Transmission_(telecommunications)" class="mw-redirect" title="Transmission (telecommunications)">transmission</a>. Once the first end is ready to accept data again, it sends XON, and the other end resumes transmission. </p><p>For example, one may imagine a <a href="/wiki/Computer" title="Computer">computer</a> sending data to a slow <a href="/wiki/Printer_(computing)" title="Printer (computing)">printer</a>. Since the computer is faster at sending data than the printer can print it, the printer falls behind and approaches a situation where it would be overwhelmed by the data. The printer reacts to this situation by sending XOFF to the computer, which temporarily stops sending data. When the printer is again ready to receive more data, it sends XON to the computer, which starts sending data again. </p><p>XOFF/XON can be employed in both directions, for example, two <a href="/wiki/Teleprinter" title="Teleprinter">teleprinters</a> connected to each other. </p> <div class="mw-heading mw-heading2"><h2 id="Comparison_with_hardware_flow_control">Comparison with hardware flow control</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Software_flow_control&action=edit&section=3" title="Edit section: Comparison with hardware flow control"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The principal advantage of software flow control is the reduction in the number of <a href="/wiki/Electrical_conductor" title="Electrical conductor">electrical conductors</a> between sender and receiver. Given a <a href="/wiki/Ground_(electricity)" title="Ground (electricity)">common ground</a>, only two signals are needed, one to send and the other to receive. Hardware flow control requires additional wires between the two devices. It also requires specific hardware implementation, which had more significant costs in earlier days of computing (i.e., 1960s and 70s). </p><p>However, software flow control is not without its problems. The most important drawback is that software flow control is less reliable. Sending XOFF requires at least one character time to transmit, and may be queued behind already-transmitted data still in buffers. Hardware signals may be asserted almost instantaneously, and out-of-order. </p><p><br /> </p> <table class="wikitable floatright"> <caption>Summary of flow control tradeoffs </caption> <tbody><tr> <th><style data-mw-deduplicate="TemplateStyles:r1038841319">.mw-parser-output .tooltip-dotted{border-bottom:1px dotted;cursor:help}</style><span class="rt-commentedText tooltip tooltip-dotted" title="Flow control method">Type</span> </th> <th><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1038841319" /><span class="rt-commentedText tooltip tooltip-dotted" title="Prevents loss of data due to buffer overruns">Data integrity</span> </th> <th><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1038841319" /><span class="rt-commentedText tooltip tooltip-dotted" title="Does not require additional wiring and electronics">Low cost</span> </th> <th><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1038841319" /><span class="rt-commentedText tooltip tooltip-dotted" title="All bytes can be transmitted without using escape mechanisms">Out of Band</span> </th></tr> <tr> <td>Hardware flow control </td> <td>Most reliable </td> <td style="background:#FFC7C7;color:black;vertical-align:middle;text-align:center;" class="table-no">No </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td></tr> <tr> <td>On-chip software f.c. </td> <td>Good </td> <td style="background: #FFD; color:black; vertical-align: middle; text-align: center;" class="partial table-partial">Some </td> <td style="background:#FFC7C7;color:black;vertical-align:middle;text-align:center;" class="table-no">No </td></tr> <tr> <td>Software f.c. (FIFO disabled) </td> <td>Good, but slow </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#FFC7C7;color:black;vertical-align:middle;text-align:center;" class="table-no">No </td></tr> <tr> <td>Software f.c. (FIFO enabled) </td> <td>Unreliable </td> <td style="background:#9EFF9E;color:black;vertical-align:middle;text-align:center;" class="table-yes">Yes </td> <td style="background:#FFC7C7;color:black;vertical-align:middle;text-align:center;" class="table-no">No </td></tr></tbody></table> <p>As the name "software flow control" implies, flow control using this method is <i>usually</i> implemented in software (or <a href="/wiki/Firmware" title="Firmware">firmware</a>), which can cause further delays in XOFF response. These delays can lead to data corruption due to <a href="/wiki/Buffer_overruns" class="mw-redirect" title="Buffer overruns">buffer overruns</a>. Hardware flow control, on the other hand, is typically under the direct control of the transmitting <a href="/wiki/Universal_asynchronous_receiver/transmitter" class="mw-redirect" title="Universal asynchronous receiver/transmitter">UART</a>, which is able to cease transmission immediately, without the intervention of higher levels. To handle the latency caused by builtin <a href="/wiki/FIFO_(computing_and_electronics)" title="FIFO (computing and electronics)">FIFOs</a>, more advanced UARTs, like the 16950, provide "on-chip" software flow control.<sup id="cite_ref-moxa_1-0" class="reference"><a href="#cite_note-moxa-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> UARTs that lack such support, like the <a href="/wiki/16550_UART" title="16550 UART">16550</a>, may suffer from buffer overruns when using software flow control, although this can be somewhat mitigated by disabling the UART's FIFO.<sup id="cite_ref-moxa_1-1" class="reference"><a href="#cite_note-moxa-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> </p><p>Finally, since the XOFF/XON codes are sent in-band, they cannot appear in the data being transmitted without being mistaken for flow control commands. Any data containing the XOFF/XON codes thus must be encoded in some manner for proper transmission, with corresponding overhead. This is frequently done with some kind of <a href="/wiki/Escape_sequence" title="Escape sequence">escape sequence</a>. For printing devices that directly interpret ASCII codes, this is not a large problem, because the XON and XOFF codes use <a href="/wiki/ASCII" title="ASCII">ASCII</a> "device control" code numbers. </p> <div class="mw-heading mw-heading2"><h2 id="Applications">Applications</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Software_flow_control&action=edit&section=4" title="Edit section: Applications"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Software flow control is used extensively by low-speed devices, especially older <a href="/wiki/Printer_(computing)" title="Printer (computing)">printers</a> and <a href="/wiki/Dumb_terminal" class="mw-redirect" title="Dumb terminal">dumb terminals</a>, to indicate they are temporarily unable to accept more data. Typically, this is due to a combination of limited <a href="/wiki/Output_(computing)" class="mw-redirect" title="Output (computing)">output</a> rate and any <a href="/wiki/Data_buffer" title="Data buffer">buffers</a> being full. Some terminal control packages, such as <a href="/wiki/Termcap" title="Termcap">termcap</a>, employ "padding" (short delays using millisecond granularity<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>) to allow such equipment sufficient time to perform the requested actions without the need to assert XOFF. </p><p>XOFF/XON are still sometimes used manually by computer operators, to pause and restart output which otherwise would <a href="/wiki/Scrolling" title="Scrolling">scroll</a> off the display too quickly. </p><p><a href="/wiki/Terminal_emulator" title="Terminal emulator">Terminal emulator</a> software generally implements XOFF/XON support as a basic function. This generally includes the <a href="/wiki/System_console" class="mw-redirect" title="System console">system console</a> on modern <a href="/wiki/Unix" title="Unix">Unix</a> and <a href="/wiki/Linux" title="Linux">Linux</a> machines, as well as <a href="/wiki/Graphical_user_interface" title="Graphical user interface">GUI</a> emulators such as <a href="/wiki/Xterm" title="Xterm">xterm</a> and the <a href="/wiki/Win32_console" class="mw-redirect" title="Win32 console">Win32 console</a>. </p><p>Robust XON is a technique to restart communication, just in case it was stopped by an accidentally received XOFF. The receiving unit sends periodic XON characters when it can receive data, and the line is idle. One common use is by serial printers (like <a href="/wiki/HP_LaserJet" title="HP LaserJet">HP LaserJet</a> II) to indicate they are online and ready to receive data. The XON is sent every 1 to 30 seconds depending on the printer's firmware design. </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=Software_flow_control&action=edit&section=5" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Ethernet_flow_control" title="Ethernet flow control">Ethernet flow control</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=Software_flow_control&action=edit&section=6" 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-moxa-1"><span class="mw-cite-backlink">^ <a href="#cite_ref-moxa_1-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-moxa_1-1"><sup><i><b>b</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 id="CITEREFYang2009" class="citation book cs1">Yang, Casper (2009). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20220804214055/https://moxa.com.cn/getmedia/2489d383-e47d-4258-94ba-9075fbeb618f/moxa-the-secrets-of-uart-fifo-tech-note-v1.0.pdf"><i>The Secrets of Flow Control in Serial Communication</i></a> <span class="cs1-format">(PDF)</span>. Moxa Tech Note (1.0 ed.). Moxa Technical Writing Center (published September 30, 2009). Archived from <a rel="nofollow" class="external text" href="https://moxa.com.cn/getmedia/2489d383-e47d-4258-94ba-9075fbeb618f/moxa-the-secrets-of-uart-fifo-tech-note-v1.0.pdf">the original</a> <span class="cs1-format">(PDF)</span> on Aug 4, 2022<span class="reference-accessdate">. Retrieved <span class="nowrap">Aug 4,</span> 2022</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Secrets+of+Flow+Control+in+Serial+Communication&rft.series=Moxa+Tech+Note&rft.edition=1.0&rft.pub=Moxa+Technical+Writing+Center&rft.date=2009&rft.aulast=Yang&rft.aufirst=Casper&rft_id=https%3A%2F%2Fmoxa.com.cn%2Fgetmedia%2F2489d383-e47d-4258-94ba-9075fbeb618f%2Fmoxa-the-secrets-of-uart-fifo-tech-note-v1.0.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASoftware+flow+control" class="Z3988"></span></span> </li> <li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.gnu.org/software/termutils/manual/termcap-1.3/html_node/termcap_10.html">"The Termcap Library - Describe Padding"</a>. <i>www.gnu.org</i>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=www.gnu.org&rft.atitle=The+Termcap+Library+-+Describe+Padding&rft_id=https%3A%2F%2Fwww.gnu.org%2Fsoftware%2Ftermutils%2Fmanual%2Ftermcap-1.3%2Fhtml_node%2Ftermcap_10.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASoftware+flow+control" class="Z3988"></span></span> </li> </ol></div></div> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20060509012616/http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=bpl06142&locale=en_US">"HP LaserJet IIP and IIP Plus Printers - Control Panel Keys and Menus"</a>. <a href="/wiki/Hewlett-Packard" title="Hewlett-Packard">Hewlett-Packard</a>. Archived from <a rel="nofollow" class="external text" href="http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=bpl06142&locale=en_US">the original</a> on May 9, 2006.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=HP+LaserJet+IIP+and+IIP+Plus+Printers+-+Control+Panel+Keys+and+Menus&rft.pub=Hewlett-Packard&rft_id=http%3A%2F%2Fh20000.www2.hp.com%2Fbizsupport%2FTechSupport%2FDocument.jsp%3FobjectID%3Dbpl06142%26locale%3Den_US&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASoftware+flow+control" class="Z3988"></span></li></ul>    </div><noscript><img src="https://auth.wikimedia.org/loginwiki/wiki/Special:CentralAutoLogin/start?useformat=desktop&type=1x1&usesul3=1" 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=Software_flow_control&oldid=1258975753">https://en.wikipedia.org/w/index.php?title=Software_flow_control&oldid=1258975753</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">Category</a>: <ul><li><a href="/wiki/Category:Flow_control_(data)" title="Category:Flow control (data)">Flow control (data)</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:Articles_with_short_description" title="Category:Articles with short description">Articles with short description</a></li><li><a href="/wiki/Category:Short_description_matches_Wikidata" title="Category:Short description matches Wikidata">Short description matches Wikidata</a></li><li><a href="/wiki/Category:Articles_needing_additional_references_from_March_2009" title="Category:Articles needing additional references from March 2009">Articles needing additional references from March 2009</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></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 22 November 2024, at 17:53<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. 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