15 lines
2.6 KiB
HTML
15 lines
2.6 KiB
HTML
<?xml version="1.0" encoding="ISO-8859-1" standalone="no"?>
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<html xmlns="http://www.w3.org/1999/xhtml"><head><title>death code</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="../D.html" title="D"/><link rel="previous" href="deadly-embrace.html" title="deadly embrace"/><link rel="next" href="Death-Square.html" title="Death Square"/></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">death code</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="deadly-embrace.html">Prev</a> </td><th width="60%" align="center">D</th><td width="20%" align="right"> <a accesskey="n" href="Death-Square.html">Next</a></td></tr></table><hr/></div><dt><a id="death-code"/><dt xmlns="" id="death-code"><b>death code</b>: <span xmlns="http://www.w3.org/1999/xhtml" class="grammar">n.</span></dt></dt><dd><p> A routine whose job is to set everything in the computer —
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registers, memory, flags, everything — to zero, including that
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portion of memory where it is running; its last act is to <a href="../S/stomp-on.html"><i class="glossterm">stomp
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on</i></a> its own “<span class="quote">store zero</span>” instruction. Death code
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isn't very useful, but writing it is an interesting hacking challenge on
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architectures where the instruction set makes it possible, such as the
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PDP-8 (it has also been done on the DG Nova).</p></dd><dd><p>Perhaps the ultimate death code is on the TI 990 series, where all
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registers are actually in RAM, and the instruction “<span class="quote">store immediate
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0</span>” has the opcode “<span class="quote">0</span>”. The PC will immediately wrap
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around core as many times as it can until a user hits HALT. Any empty
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memory location is death code. Worse, the manufacturer recommended use of
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this instruction in startup code (which would be in ROM and therefore
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survive).</p></dd><div class="navfooter"><hr/><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="deadly-embrace.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="../D.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="Death-Square.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">deadly embrace </td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"> Death Square</td></tr></table></div></body></html>
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