12 lines
2.4 KiB
HTML
12 lines
2.4 KiB
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<?xml version="1.0" encoding="ISO-8859-1" standalone="no"?>
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<html xmlns="http://www.w3.org/1999/xhtml"><head><title>speedometer</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="../S.html" title="S"/><link rel="previous" href="speed-of-light.html" title="speed of light"/><link rel="next" href="spell.html" title="spell"/></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">speedometer</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="speed-of-light.html">Prev</a><EFBFBD></td><th width="60%" align="center">S</th><td width="20%" align="right"><EFBFBD><a accesskey="n" href="spell.html">Next</a></td></tr></table><hr/></div><dt><a id="speedometer"/><dt xmlns="" id="speedometer"><b>speedometer</b>: <span xmlns="http://www.w3.org/1999/xhtml" class="grammar">n.</span></dt></dt><dd><p> A pattern of lights displayed on a linear set of LEDs (today) or
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nixie tubes (yesterday, on ancient mainframes). The pattern is shifted
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left every <tt class="literal">N</tt> times the operating system
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goes through its <a href="../M/main-loop.html"><i class="glossterm">main loop</i></a>. A swiftly moving
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pattern indicates that the system is mostly idle; the speedometer slows
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down as the system becomes overloaded. The speedometer on Sun Microsystems
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hardware bounces back and forth like the eyes on one of the Cylons from the
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wretched <i class="citetitle">Battlestar Galactica</i> TV series.</p></dd><dd><p>Historical note: One computer, the GE 600 (later Honeywell 6000)
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actually had an <span class="emphasis"><em>analog</em></span> speedometer on the front panel,
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calibrated in instructions executed per second.</p></dd><div class="navfooter"><hr/><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="speed-of-light.html">Prev</a><EFBFBD></td><td width="20%" align="center"><a accesskey="u" href="../S.html">Up</a></td><td width="40%" align="right"><EFBFBD><a accesskey="n" href="spell.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">speed of light<68></td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"><EFBFBD>spell</td></tr></table></div></body></html>
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