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<html xmlns="http://www.w3.org/1999/xhtml"><head><title>The Story of Mel</title><link rel="stylesheet" href="jargon.css" type="text/css"/><meta name="generator" content="DocBook XSL Stylesheets V1.61.0"/><link rel="home" href="index.html" title="The Jargon File"/><link rel="up" href="appendixa.html" title="Appendix A. Hacker Folklore"/><link rel="previous" href="os-and-jedgar.html" title="OS and JEDGAR"/><link rel="next" href="appendixb.html" title="Appendix B. A Portrait of J. Random Hacker"/></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">The Story of Mel</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="os-and-jedgar.html">Prev</a> </td><th width="60%" align="center">Appendix A. Hacker Folklore</th><td width="20%" align="right"> <a accesskey="n" href="appendixb.html">Next</a></td></tr></table><hr/></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="story-of-mel"/>The Story of Mel</h2></div></div><div/></div><p>This was posted to Usenet by its author, Ed Nather
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(<tt class="email"><<a href="mailto:nather@astro.as.utexas.edu">nather@astro.as.utexas.edu</a>></tt>), on May 21, 1983.</p><div class="literallayout"><p><br/>
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A recent article devoted to the <span class="emphasis"><em>macho</em></span> side of programming<br/>
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made the bald and unvarnished statement:<br/>
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<br/>
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Real Programmers write in FORTRAN.<br/>
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<br/>
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Maybe they do now,<br/>
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in this decadent era of<br/>
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Lite beer, hand calculators, and “<span class="quote">user-friendly</span>” software<br/>
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but back in the Good Old Days,<br/>
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when the term “<span class="quote">software</span>” sounded funny<br/>
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and Real Computers were made out of drums and vacuum tubes,<br/>
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Real Programmers wrote in machine code.<br/>
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Not FORTRAN. Not RATFOR. Not, even, assembly language.<br/>
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Machine Code.<br/>
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Raw, unadorned, inscrutable hexadecimal numbers.<br/>
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Directly.<br/>
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<br/>
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Lest a whole new generation of programmers<br/>
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grow up in ignorance of this glorious past,<br/>
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I feel duty-bound to describe,<br/>
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as best I can through the generation gap,<br/>
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how a Real Programmer wrote code.<br/>
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I'll call him Mel,<br/>
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because that was his name.<br/>
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<br/>
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I first met Mel when I went to work for Royal McBee Computer Corp.,<br/>
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a now-defunct subsidiary of the typewriter company.<br/>
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The firm manufactured the LGP-30,<br/>
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a small, cheap (by the standards of the day)<br/>
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drum-memory computer,<br/>
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and had just started to manufacture<br/>
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the RPC-4000, a much-improved,<br/>
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bigger, better, faster — drum-memory computer.<br/>
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Cores cost too much,<br/>
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and weren't here to stay, anyway.<br/>
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(That's why you haven't heard of the company,<br/>
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or the computer.)<br/>
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<br/>
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I had been hired to write a FORTRAN compiler<br/>
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for this new marvel and Mel was my guide to its wonders.<br/>
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Mel didn't approve of compilers.<br/>
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<br/>
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“<span class="quote">If a program can't rewrite its own code</span>”,<br/>
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he asked, “<span class="quote">what good is it?</span>”<br/>
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<br/>
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Mel had written,<br/>
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in hexadecimal,<br/>
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the most popular computer program the company owned.<br/>
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It ran on the LGP-30<br/>
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and played blackjack with potential customers<br/>
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at computer shows.<br/>
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Its effect was always dramatic.<br/>
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The LGP-30 booth was packed at every show,<br/>
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and the IBM salesmen stood around<br/>
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talking to each other.<br/>
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Whether or not this actually sold computers<br/>
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was a question we never discussed.<br/>
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<br/>
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Mel's job was to re-write<br/>
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the blackjack program for the RPC-4000.<br/>
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(Port? What does that mean?)<br/>
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The new computer had a one-plus-one<br/>
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addressing scheme,<br/>
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in which each machine instruction,<br/>
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in addition to the operation code<br/>
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and the address of the needed operand,<br/>
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had a second address that indicated where, on the revolving drum,<br/>
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the next instruction was located.<br/>
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<br/>
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In modern parlance,<br/>
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every single instruction was followed by a GO TO!<br/>
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Put <span class="emphasis"><em>that</em></span> in Pascal's pipe and smoke it.<br/>
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<br/>
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Mel loved the RPC-4000<br/>
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because he could optimize his code:<br/>
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that is, locate instructions on the drum<br/>
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so that just as one finished its job,<br/>
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the next would be just arriving at the “<span class="quote">read head</span>”<br/>
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and available for immediate execution.<br/>
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There was a program to do that job,<br/>
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an “<span class="quote">optimizing assembler</span>”,<br/>
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but Mel refused to use it.<br/>
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<br/>
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“<span class="quote">You never know where it's going to put things</span>”,<br/>
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he explained, “<span class="quote">so you'd have to use separate constants</span>”.<br/>
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<br/>
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It was a long time before I understood that remark.<br/>
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Since Mel knew the numerical value<br/>
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of every operation code,<br/>
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and assigned his own drum addresses,<br/>
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every instruction he wrote could also be considered<br/>
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a numerical constant.<br/>
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He could pick up an earlier “<span class="quote">add</span>” instruction, say,<br/>
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and multiply by it,<br/>
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if it had the right numeric value.<br/>
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His code was not easy for someone else to modify.<br/>
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<br/>
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I compared Mel's hand-optimized programs<br/>
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with the same code massaged by the optimizing assembler program,<br/>
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and Mel's always ran faster.<br/>
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That was because the “<span class="quote">top-down</span>” method of program design<br/>
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hadn't been invented yet,<br/>
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and Mel wouldn't have used it anyway.<br/>
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He wrote the innermost parts of his program loops first,<br/>
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so they would get first choice<br/>
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of the optimum address locations on the drum.<br/>
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The optimizing assembler wasn't smart enough to do it that way.<br/>
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<br/>
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Mel never wrote time-delay loops, either,<br/>
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even when the balky Flexowriter<br/>
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required a delay between output characters to work right.<br/>
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He just located instructions on the drum<br/>
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so each successive one was just <span class="emphasis"><em>past</em></span> the read head<br/>
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when it was needed;<br/>
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the drum had to execute another complete revolution<br/>
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to find the next instruction.<br/>
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He coined an unforgettable term for this procedure.<br/>
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Although “<span class="quote">optimum</span>” is an absolute term,<br/>
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like “<span class="quote">unique</span>”, it became common verbal practice<br/>
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to make it relative:<br/>
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“<span class="quote">not quite optimum</span>” or “<span class="quote">less optimum</span>”<br/>
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or “<span class="quote">not very optimum</span>”.<br/>
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Mel called the maximum time-delay locations<br/>
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the “<span class="quote">most pessimum</span>”.<br/>
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<br/>
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After he finished the blackjack program<br/>
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and got it to run<br/>
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(“<span class="quote">Even the initializer is optimized</span>”,<br/>
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he said proudly),<br/>
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he got a Change Request from the sales department.<br/>
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The program used an elegant (optimized)<br/>
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random number generator<br/>
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to shuffle the “<span class="quote">cards</span>” and deal from the “<span class="quote">deck</span>”,<br/>
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and some of the salesmen felt it was too fair,<br/>
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since sometimes the customers lost.<br/>
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They wanted Mel to modify the program<br/>
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so, at the setting of a sense switch on the console,<br/>
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they could change the odds and let the customer win.<br/>
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<br/>
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Mel balked.<br/>
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He felt this was patently dishonest,<br/>
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which it was,<br/>
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and that it impinged on his personal integrity as a programmer,<br/>
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which it did,<br/>
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so he refused to do it.<br/>
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The Head Salesman talked to Mel,<br/>
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as did the Big Boss and, at the boss's urging,<br/>
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a few Fellow Programmers.<br/>
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Mel finally gave in and wrote the code,<br/>
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but he got the test backwards,<br/>
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and, when the sense switch was turned on,<br/>
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the program would cheat, winning every time.<br/>
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Mel was delighted with this,<br/>
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claiming his subconscious was uncontrollably ethical,<br/>
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and adamantly refused to fix it.<br/>
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<br/>
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After Mel had left the company for greener pa$ture$,<br/>
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the Big Boss asked me to look at the code<br/>
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and see if I could find the test and reverse it.<br/>
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Somewhat reluctantly, I agreed to look.<br/>
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Tracking Mel's code was a real adventure.<br/>
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<br/>
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I have often felt that programming is an art form,<br/>
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whose real value can only be appreciated<br/>
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by another versed in the same arcane art;<br/>
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there are lovely gems and brilliant coups<br/>
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hidden from human view and admiration, sometimes forever,<br/>
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by the very nature of the process.<br/>
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You can learn a lot about an individual<br/>
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just by reading through his code,<br/>
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even in hexadecimal.<br/>
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Mel was, I think, an unsung genius.<br/>
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<br/>
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Perhaps my greatest shock came<br/>
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when I found an innocent loop that had no test in it.<br/>
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No test. <span class="emphasis"><em>None</em></span>.<br/>
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Common sense said it had to be a closed loop,<br/>
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where the program would circle, forever, endlessly.<br/>
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Program control passed right through it, however,<br/>
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and safely out the other side.<br/>
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It took me two weeks to figure it out.<br/>
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<br/>
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The RPC-4000 computer had a really modern facility<br/>
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called an index register.<br/>
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It allowed the programmer to write a program loop<br/>
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that used an indexed instruction inside;<br/>
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each time through,<br/>
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the number in the index register<br/>
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was added to the address of that instruction,<br/>
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so it would refer<br/>
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to the next datum in a series.<br/>
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He had only to increment the index register<br/>
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each time through.<br/>
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Mel never used it.<br/>
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<br/>
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Instead, he would pull the instruction into a machine register,<br/>
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add one to its address,<br/>
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and store it back.<br/>
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He would then execute the modified instruction<br/>
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right from the register.<br/>
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The loop was written so this additional execution time<br/>
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was taken into account —<br/>
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just as this instruction finished,<br/>
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the next one was right under the drum's read head,<br/>
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ready to go.<br/>
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But the loop had no test in it.<br/>
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<br/>
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The vital clue came when I noticed<br/>
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the index register bit,<br/>
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the bit that lay between the address<br/>
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and the operation code in the instruction word,<br/>
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was turned on —<br/>
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yet Mel never used the index register,<br/>
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leaving it zero all the time.<br/>
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When the light went on it nearly blinded me.<br/>
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<br/>
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He had located the data he was working on<br/>
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near the top of memory —<br/>
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the largest locations the instructions could address —<br/>
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so, after the last datum was handled,<br/>
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incrementing the instruction address<br/>
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would make it overflow.<br/>
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The carry would add one to the<br/>
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operation code, changing it to the next one in the instruction set:<br/>
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a jump instruction.<br/>
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Sure enough, the next program instruction was<br/>
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in address location zero,<br/>
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and the program went happily on its way.<br/>
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<br/>
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I haven't kept in touch with Mel,<br/>
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so I don't know if he ever gave in to the flood of<br/>
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change that has washed over programming techniques<br/>
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since those long-gone days.<br/>
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I like to think he didn't.<br/>
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In any event,<br/>
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I was impressed enough that I quit looking for the<br/>
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offending test,<br/>
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telling the Big Boss I couldn't find it.<br/>
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He didn't seem surprised.<br/>
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<br/>
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When I left the company,<br/>
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the blackjack program would still cheat<br/>
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if you turned on the right sense switch,<br/>
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and I think that's how it should be.<br/>
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I didn't feel comfortable<br/>
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hacking up the code of a Real Programmer.<br/>
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</p></div><p>This is one of hackerdom's great heroic epics, free verse or no. In a
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few spare images it captures more about the esthetics and psychology of
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hacking than all the scholarly volumes on the subject put together. (But for
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an opposing point of view, see the entry for
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<a href="R/Real-Programmer.html"><i class="glossterm">Real Programmer</i></a>.)</p><p>[1992 postscript — the author writes: “The original
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submission to the net was not in free verse, nor any approximation to it
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— it was straight prose style, in non-justified paragraphs. In bouncing
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around the net it apparently got modified into the ‘free verse' form now
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popular. In other words, it got hacked on the net. That seems appropriate,
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somehow.” The author adds that he likes the ‘free-verse' version
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better than his prose original...]</p><p>[1999 update: Mel's last name is now known. The manual for the LGP-30
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refers to “<span class="quote">Mel Kaye of Royal McBee who did the bulk of the programming
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[...] of the ACT 1 system</span>”.]</p><p>[2001: The Royal McBee LPG-30 turns out to have one other claim to
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fame. It turns out that meteorologist Edward Lorenz was doing weather
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simulations on an LGP-30 when, in 1961, he discovered the “<span class="quote">Butterfly
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Effect</span>” and computational chaos. This seems, somehow,
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appropriate.]</p><p>[2002: A copy of the programming manual for the LGP-30 lives at <a href="http://ed-thelen.org/comp-hist/lgp-30-man.html" target="_top">http://ed-thelen.org/comp-hist/lgp-30-man.html</a>]</p></div><div class="navfooter"><hr/><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="os-and-jedgar.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="appendixa.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="appendixb.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">OS and JEDGAR </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Appendix B. A Portrait of J. Random Hacker</td></tr></table></div></body></html>
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