39 lines
2.5 KiB
Plaintext
39 lines
2.5 KiB
Plaintext
timesharing
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Timesharing is the technique of scheduling a computer's time so that they
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are shared across multiple tasks and multiple users, with each user having
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the illusion that his or her computation is going on continuously. John
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McCarthy, the inventor of LISP , first imagined this technique in the late
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1950s. The first timesharing operating systems, BBN's Little Hospital and
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CTSS , were deplayed in 1962-63. The early hacker culture of the 1960s and
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1970s grew up around the first generation of relatively cheap timesharing
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computers, notably the DEC 10, 11, and VAX lines. But these were only cheap
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in a relative sense; though quite a bit less powerful than today's personal
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computers, they had to be shared by dozens or even hundreds of people each.
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The early hacker comunities nucleated around places where it was relatively
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easy to get access to a timesharing account. Nowadays, communications
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bandwidth is usually the most important constraint on what you can do with
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your computer. Not so back then; timesharing machines were often loaded to
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capacity, and it was not uncommon for everyone's work to grind to a halt
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while the machine scheduler thrashed, trying to figure out what to do next.
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Early hacker slang was replete with terms like cycle crunch and cycle
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drought for describing the consequences of too few instructions-per-second
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spread among too many users. As GLS has noted, this sort of problem
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influenced the tendency of many hackers to work odd schedules. One reason
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this is worth noting here is to make the point that the earliest hacker
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communities were physical, not distributed via networks; they consisted of
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hackers who shared a machine and therefore had to deal with many of the same
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problems with respect to it. A system crash could idle dozens of eager
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programmers, all sitting in the same terminal room and with little to do but
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talk with each other until normal operation resumed. Timesharing moved from
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being the luxury of a few large universities runing semi-experimental
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operating systems to being more generally available about 1975-76. Hackers
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in search of more cycles and more control over their programming environment
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began to migrate off timesharing machines and onto what are now called
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workstations around 1983. It took another ten years, the development of
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powerful 32-bit personal micros, the Great Internet Explosion before the
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migration was complete. It is no coincidence that the last stages of this
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migration coincided with the development of the first open-source operating
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systems.
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