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Decimal computer
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<p>A decimal computer is a <a href="/facts/Computer/SQe1aK05">computer</a> that represents and operates on <a href="/facts/Number/auQSAE2m">numbers</a> and <a href="/facts/Memory_address/7EsUmbea">addresses</a> in <a href="/facts/Decimal/7omfVNIM">decimal</a> format – instead of <a href="/facts/Binary_number/a6JDSRPs">binary</a> as is common in most modern computers. Some decimal computers had a variable <a href="/facts/Word_length/2e5umRaj">word length</a>, which enabled operations on relatively large numbers. </p><p>Decimal computers were common from the early machines through the 1960s and into the 1970s. Using decimal directly saved the need to convert from decimal to binary for <a href="/facts/Input%2foutput/WQTE8Jas">input and output</a> and offered a significant speed improvement over binary machines that performed these conversions using subroutines. This allowed otherwise low-end machines to offer practical performance for roles like <a href="/facts/Accounting/sHznDY3V">accounting</a> and <a href="/facts/Bookkeeping/zHglNNjd">bookkeeping</a>, and many low- and mid-range systems of the era were decimal based. </p><p>The <a href="/facts/IBM_System%2f360/7znvpy4K">IBM System/360</a> line of binary computers, announced in 1964, included instructions that perform decimal arithmetic; other lines of binary computers with decimal arithmetic instructions followed. During the 1970s, <a href="/facts/Microprocessor/Fx9CaQht">microprocessors</a> with instructions supporting decimal arithmetic became common in <a href="/facts/Electronic_calculator/eeLfRS8L">electronic calculators</a>, <a href="/facts/Cash_register/GsBX9b8V">cash registers</a> and similar roles, especially in the 8-bit era. </p><p>The rapid improvements in general performance of binary machines eroded the value of decimal operations. One of the last major new designs to support it was the <a href="/facts/Motorola_68000/3p2wt2D6">Motorola 68000</a>, which shipped in 1980. More recently, <a href="/facts/IBM/QszA7nwd">IBM</a> added decimal support to their <a href="/facts/POWER6/GqfSuMVM">POWER6</a> designs to allow them to directly support programs written for 1960s platforms like the <a href="/facts/System%2f360/7znvpy4K">System/360</a>. With that exception, most modern designs have little or no decimal support. </p>