Autonetics Recomp II

<h2 id="architecture">Architecture</h2>
<p>It had a 40-bit word size, 20-bit instruction size. Memory and registers were on a fixed head disk that operated like a <a href="/facts/Drum_memory/yul0r8nG">drum memory</a>—4080 words on standard tracks, 16 words on fast loop tracks, registers A, B, R, X each on their own high-speed loop track, and one prerecorded <a href="/facts/Read-only_memory/P9QMuDLH">read only</a> clock track.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a>
</p><p>It had a complete set of built-in <a href="/facts/Floating_point_operation/6zYlH68F">floating point operations</a>, including <a href="/facts/Square_root/AfrzfBdQ">square root</a>. Floating-point values used two words, one for the exponent and one for the fraction for a total of 80 bits.
</p><p>Whereas the full 40-bit word was used for data, instructions were only 20 bits long and were stored two per word.  Since indexing was commonly done by modifying the address part of an instruction (say, by adding one to access the next data item in a list), such instructions always had to be in the second half-word, and the first half-word was padded with a <a href="/facts/NOP_(code)/uGcGefyG">NOP</a> instruction.  Programmers also used these NOP instructions to provide space for future inserted instructions, since the assembler did not allow for use of symbolic addresses, and the insertion of a single instruction could otherwise require rewriting a lot of code.
</p><p>The machine had a <a href="/facts/Bit-serial_architecture/I7FlkhFk">bit-serial architecture</a>.
</p><p><a href="/facts/Punched_paper_tape/8HI7dThI">Punched paper tape</a> was the external storage medium.  The desk also had an electronic typewriter for printed output and a keyboard integrated with the system console to allow typed input and system control.  Programs written in machine code could be input to the system from the console.
</p>

<h2 id="further-reading">Further reading</h2>
<ul><li><a href="http://www.bitsavers.org/pdf/auerbach/Auerbach_Standard_EDP_Reports_196609_Volume_2_Autonetics-CDC.pdf">"RECOMP II"</a> (PDF). <i>AUERBACH Standard EDP Reports</i>. 2: 6–9.</li></ul>
<h2 id="external-links">External links</h2>
<ul><li><a href="http://www.bitsavers.org/pdf/autonetics/recomp">Autonetics RECOMP II documents</a> On Bitsavers.org</li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>D, Goldstein, Gordon (January 1958). "COMPUTERS AND DATA PROCESSORS. NORTH AMERICA - Autonetics, RECOMP II, Downey, California". Digital Computer Newsletter. 10 (1): 1.{{cite journal}}:  CS1 maint: multiple names: authors list (link)[dead link] <a href="http://www.dtic.mil/docs/citations/AD0694627" target="_blank">http://www.dtic.mil/docs/citations/AD0694627</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Weik, Martin H. (Mar 1961). "RECOMP II". ed-thelen.org. A Third Survey of Domestic Electronic Digital Computing Systems. <a href="http://www.ed-thelen.org/comp-hist/BRL61-r.html#RECOMP-II" target="_blank">http://www.ed-thelen.org/comp-hist/BRL61-r.html#RECOMP-II</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>Autonetics Recomp Theory of Operation <a href="http://bitsavers.trailing-edge.com/pdf/autonetics/recomp/555-A-14_RECOMP_Theory_Of_Operation_May62.pdf" target="_blank">http://bitsavers.trailing-edge.com/pdf/autonetics/recomp/555-A-14_RECOMP_Theory_Of_Operation_May62.pdf</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
</ol>

Autonetics Recomp II open-in-new

Autonetics Recomp II