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Industry Standard Architecture
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<p>Industry Standard Architecture (ISA) is the <a href="/facts/16-bit/bTGS44Ne">16-bit</a> internal <a href="/facts/Bus_(computing)/R45TKwS7">bus</a> of <a href="/facts/IBM_PC%2fAT/YEVHpWKF">IBM PC/AT</a> and similar computers based on the <a href="/facts/Intel_80286/rucEU93g">Intel 80286</a> and its immediate successors during the 1980s. The bus was (largely) <a href="/facts/Backward_compatible/FbHFBu5y">backward compatible</a> with the <a href="/facts/8-bit/2CkhLNoH">8-bit</a> bus of the <a href="/facts/8088/DdWKfyBp">8088</a>-based <a href="/facts/IBM_PC/yhcJGMPL">IBM PC</a>, including the <a href="/facts/IBM_PC%2fXT/5uHxtq6H">IBM PC/XT</a> as well as <a href="/facts/IBM_PC_compatible/zGUpl7Sh">IBM PC compatibles</a>. </p><p>Originally referred to as the PC bus (8-bit) or AT bus (16-bit), it was also termed <i>I/O Channel</i> by IBM. The ISA term was coined as a <a href="/facts/Retronym/yBLuNepw">retronym</a> by IBM PC clone manufacturers in the late 1980s or early 1990s as a reaction to IBM attempts to replace the AT bus with its new and incompatible <a href="/facts/Micro_Channel_architecture/63TW6aq4">Micro Channel architecture</a>. </p><p>The 16-bit ISA bus was also used with 32-bit processors for several years. An attempt to extend it to 32 bits, called <a href="/facts/Extended_Industry_Standard_Architecture/paLar9py">Extended Industry Standard Architecture</a> (EISA), was not very successful, however. Later buses such as <a href="/facts/VESA_Local_Bus/IcI38QT9">VESA Local Bus</a> and <a href="/facts/Peripheral_Component_Interconnect/n6CGuFvP">PCI</a> were used instead, often along with ISA slots on the same <a href="/facts/Mainboard/GXB10heG">mainboard</a>. Derivatives of the AT bus structure were and still are used in <a href="/facts/ATA%2fIDE/QPchqXH8">ATA/IDE</a>, the <a href="/facts/PCMCIA/ATXtE8rd">PCMCIA</a> standard, <a href="/facts/CompactFlash/0sxFM3qt">CompactFlash</a>, the <a href="/facts/PC%2f104/qYlwqJ4N">PC/104</a> bus, and internally within <a href="/facts/Super_I%2fO/qfa6l5g5">Super I/O</a> chips. </p><p>Even though ISA disappeared from consumer desktops many years ago, it is still used in <a href="/facts/Industrial_PC/KDgJ24B7">industrial PCs</a>, where certain specialized expansion cards that never transitioned to PCI and PCI Express are used. </p>