timesharing
n . 分時
time -
sharing 分時
timesharing 分時
timesharing [
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 .
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