<span class="mw-page-title-main">S-100 bus</span>

S-100 bus

<p>The <b>S-100 bus</b> or <b>Altair bus</b>, <b>IEEE 696-1983</b> <i>(withdrawn)</i>, is an early <a href="/en/Computer_bus" title="Computer bus" class="mw-redirect wl">computer bus</a> designed in 1974 as a part of the <a href="/en/Altair_8800" title="Altair 8800" class="wl">Altair 8800</a>. The <span class="nowrap">S-100</span> bus was the first industry standard <a href="/en/Expansion_bus" title="Expansion bus" class="mw-redirect wl">expansion bus</a> for the microcomputer industry. <span class="nowrap">S-100</span> computers, consisting of processor and peripheral cards, were produced by a number of manufacturers.  The <span class="nowrap">S-100</span> bus formed the basis for homebrew computers whose builders (e.g., the <a href="/en/Homebrew_Computer_Club" title="Homebrew Computer Club" class="wl">Homebrew Computer Club</a>) implemented drivers for <a href="/en/CP/M" title="CP/M" class="wl">CP/M</a> and <a href="/en/MP/M" title="MP/M" class="wl">MP/M</a>.  These <span class="nowrap">S-100</span> microcomputers ran the gamut from hobbyist toy to small business workstation and were common in early <a href="/en/Home_computers" title="Home computers" class="mw-redirect wl">home computers</a> until the advent of the <a href="/en/IBM_PC" title="IBM PC" class="mw-redirect wl">IBM PC</a>.</p>

<figure class="mw-default-size wiki-thumb"><a href="/en/File:Harry_Garland_and_Roger_Melen,_co-founders_of_Cromemco_(1981).jpg" class="mw-file-description image media-thumb" data-hash="File:Harry_Garland_and_Roger_Melen,_co-founders_of_Cromemco_(1981).jpg"><img loading="lazy" src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b7/Harry_Garland_and_Roger_Melen%2C_co-founders_of_Cromemco_%281981%29.jpg/220px-Harry_Garland_and_Roger_Melen%2C_co-founders_of_Cromemco_%281981%29.jpg" decoding="async" data-file-width="1344" data-file-height="1152" data-file-type="bitmap" height="189" width="220" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/b7/Harry_Garland_and_Roger_Melen%2C_co-founders_of_Cromemco_%281981%29.jpg/330px-Harry_Garland_and_Roger_Melen%2C_co-founders_of_Cromemco_%281981%29.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/b7/Harry_Garland_and_Roger_Melen%2C_co-founders_of_Cromemco_%281981%29.jpg/440px-Harry_Garland_and_Roger_Melen%2C_co-founders_of_Cromemco_%281981%29.jpg 2x" alt="Harry_Garland_and_Roger_Melen%2C_co-founders_of_Cromemco_%281981%29.jpg"></a><figcaption><a href="/en/Harry_Garland" title="Harry Garland" class="wl">Harry Garland</a> and <a href="/en/Roger_Melen" title="Roger Melen" class="wl">Roger Melen</a>, co-founders of <a href="/en/Cromemco" title="Cromemco" class="wl">Cromemco</a>, holding an <span class="nowrap">S-100</span> backplane (1981)</figcaption></figure>

<div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none" about="#mwt1">Early computer bus</div>
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<style data-mw-deduplicate="TemplateStyles:r1066479718" typeof="mw:Extension/templatestyles mw:Transclusion">.mw-parser-output .infobox-subbox{padding:0;border:none;margin:-3px;width:auto;min-width:100%;font-size:100%;clear:none;float:none;background-color:transparent}.mw-parser-output .infobox-3cols-child{margin:auto}.mw-parser-output .infobox .navbar{font-size:100%}body.skin-minerva .mw-parser-output .infobox-header,body.skin-minerva .mw-parser-output .infobox-subheader,body.skin-minerva .mw-parser-output .infobox-above,body.skin-minerva .mw-parser-output .infobox-title,body.skin-minerva .mw-parser-output .infobox-image,body.skin-minerva .mw-parser-output .infobox-full-data,body.skin-minerva .mw-parser-output .infobox-below{text-align:center}</style><div class='mobile-collapse'><header class="mobile-collapse-header mobile-collapse-btn"><b>Quick facts: Year created, Created by, Width in bits...</b> <span class='arrow'>▼</span></header> <table class="infobox mobile-collapse-element"><caption class="infobox-title">S-100 bus</caption><tbody><tr><td colspan="2" class="infobox-image"><span class="mw-default-size"><a href="/en/File:Cromemco_Blitz_Bus.jpg" class="mw-file-description image media-thumb" data-hash="File:Cromemco_Blitz_Bus.jpg"><img loading="lazy" src="//upload.wikimedia.org/wikipedia/commons/thumb/a/ad/Cromemco_Blitz_Bus.jpg/220px-Cromemco_Blitz_Bus.jpg" decoding="async" data-file-width="3228" data-file-height="1797" data-file-type="bitmap" height="122" width="220" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/ad/Cromemco_Blitz_Bus.jpg/330px-Cromemco_Blitz_Bus.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/ad/Cromemco_Blitz_Bus.jpg/440px-Cromemco_Blitz_Bus.jpg 2x" alt="Cromemco_Blitz_Bus.jpg"></a></span></td></tr><tr><th scope="row" class="infobox-label">Year created</th><td class="infobox-data">1974<span class="noprint"><span>;</span><span> </span>49<span>&nbsp;</span>years ago</span><span style="display:none"><span>&nbsp;</span>(<span class="bday dtstart published updated">1974</span>)</span></td></tr><tr><th scope="row" class="infobox-label">Created by</th><td class="infobox-data"><a href="/en/Ed_Roberts_(computer_engineer)" title="Ed Roberts (computer engineer)" class="wl">Ed Roberts</a></td></tr><tr><th scope="row" class="infobox-label">Width in bits</th><td class="infobox-data">8</td></tr></tbody></table> <footer class='mobile-collapse-footer mobile-collapse-btn'><b>Close</b> <span class='arrow'>▲</span></footer></div>


The S-100 bus or Altair bus, IEEE 696-1983 , is an early computer bus designed in 1974 as a part of the Altair 8800. The S-100 bus was the first industry standard expansion bus for the microcomputer industry. S-100 computers, consisting of processor and peripheral cards, were produced by a number of manufacturers.  The S-100 bus formed the basis for homebrew computers whose builders implemented drivers for CP/M and MP/M.  These S-100 microcomputers ran the gamut from hobbyist toy to small business workstation and were common in early home computers until the advent of the IBM PC. 