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