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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>timesharing</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="../T.html" title="T"/><link rel="previous" href="times-or-divided-by.html" title="times-or-divided-by"/><link rel="next" href="TINC.html" title="TINC"/></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">timesharing</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="times-or-divided-by.html">Prev</a><EFBFBD></td><th width="60%" align="center">T</th><td width="20%" align="right"><EFBFBD><a accesskey="n" href="TINC.html">Next</a></td></tr></table><hr/></div><dt><a id="timesharing"/><dt xmlns="" id="timesharing"><b>timesharing</b></dt></dt><dd><p>[now primarily historical] Timesharing is the technique of scheduling
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a computer's time so that they are shared across multiple tasks and
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multiple users, with each user having the illusion that his or her
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computation is going on continuously. John McCarthy, the inventor of
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<a href="../L/LISP.html"><i class="glossterm">LISP</i></a>, first <a href="http://www-formal.stanford.edu/jmc/history/timesharing/timesharing.html" target="_top">imagined
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this technique</a> in the late 1950s. The first timesharing operating
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systems, BBN's "Little Hospital" and <a href="../C/CTSS.html"><i class="glossterm">CTSS</i></a>, were
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deplayed in 1962-63. The early hacker culture of the 1960s and 1970s grew
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up around the first generation of relatively cheap timesharing computers,
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notably the <a href="../D/DEC.html"><i class="glossterm">DEC</i></a> 10, 11, and <a href="../V/VAX.html"><i class="glossterm">VAX</i></a> lines. But these
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were only cheap in a relative sense; though quite a bit less powerful than
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today's personal computers, they had to be shared by dozens or even
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hundreds of people each. The early hacker comunities nucleated around
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places where it was relatively easy to get access to a timesharing
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account.</p><p>Nowadays, communications bandwidth is usually the most important
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constraint on what you can do with your computer. Not so back then;
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timesharing machines were often loaded to capacity, and it was not uncommon
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for everyone's work to grind to a halt while the machine scheduler
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thrashed, trying to figure out what to do next. Early hacker slang
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was replete with terms like <span class="firstterm">cycle
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crunch</span> and <span class="firstterm">cycle drought</span>
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for describing the consequences of too few instructions-per-second spread
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among too many users. As GLS has noted, this sort of problem influenced
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the tendency of many hackers to work odd schedules.</p><p>One reason this is worth noting here is to make the point that the
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earliest hacker communities were physical, not distributed via networks;
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they consisted of hackers who shared a machine and therefore had to deal
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with many of the same problems with respect to it. A system crash could
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idle dozens of eager programmers, all sitting in the same terminal room and
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with little to do but talk with each other until normal operation
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resumed.</p><p>Timesharing moved from being the luxury of a few large universities
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runing semi-experimental operating systems to being more generally
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available about 1975-76. Hackers in search of more cycles and more control
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over their programming environment began to migrate off timesharing
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machines and onto what are now called <span class="firstterm">workstations</span> around 1983. It took another ten
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years, the development of powerful 32-bit personal micros, the
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<a href="../G/Great-Internet-Explosion.html"><i class="glossterm">Great Internet Explosion</i></a> before the migration was
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complete. It is no coincidence that the last stages of this migration
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coincided with the development of the first open-source operating
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systems.</p></dd><div class="navfooter"><hr/><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="times-or-divided-by.html">Prev</a><EFBFBD></td><td width="20%" align="center"><a accesskey="u" href="../T.html">Up</a></td><td width="40%" align="right"><EFBFBD><a accesskey="n" href="TINC.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">times-or-divided-by<62></td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"><EFBFBD>TINC</td></tr></table></div></body></html>
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