| Re: [OT] Pre-emptive multi-tasking [message #180972 is a reply to message #180971] |
Fri, 29 March 2013 17:13   |
The Natural Philosoph
Messages: 993
Registered: September 2010
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On 29/03/13 16:57, Tim Streater wrote:
> In article <1905400(dot)vG1O3Ob32A(at)PointedEars(dot)de>,
> Thomas 'PointedEars' Lahn <PointedEars(at)web(dot)de> wrote:
>
>> Tim Streater wrote:
>>
>>> The Natural Philosopher <tnp(at)invalid(dot)invalid> wrote:
>>>> cant you come up with something better than that? like " *nix had
>> proper
>>>> pre-emptive multi tasking years before os9 and windows failed to
>>>> implement it correctly"
>>>> And plenty of OSes had it before unix.
>>
>> No, according to <http://en.wikipedia.org/wiki/Pre-
>> emptive_multitasking#Systems_supporting_preemptive_multitasking> and
>> <http://en.wikipedia.org/wiki/Unix>, Unix, at Bell Labs, was the first
>> operating system to support *pre-emptive* _multi-tasking_, in
>> 1969/1970 (hence the Unix timestamp 0 equals 1970-01-01 00:00:00 UTC)
>> as an improvement to the time-sharing Multics (1964) where
>> multi-tasking was first implemented. Sinclair QDOS (1984) and Amiga
>> OS (1985) and other operating systems (particularly the Unix-like
>> ones) followed Unix in that regard.
>
> My timeline had unix starting in the 70s but no matter. Certainly the OS
> I was using 1970-78 at CERN, running on a French-built Sigma7 and called
> Siris7, had pre-emptive multitasking. And I'm not sure that the Atlas
> Supervisor (1962) didn't do it too.
>
multitasking goes back a long way but pre-emptive does not go back as far.
Certainly Unix was one of the earliest , but that may have been because
the hardware it came on had the right sort of interrupts.
> The concepts were all there by that point for anyone to organise into an
> OS, which we did once or twice in our group at CERN.
>
Indeed. I've written a couple of schedulersto do pre-emptive
multitasking..one on DOS2.2!!!
there isn't much need to turn ordinary multitasking into pre-emptive,
but there is not much point in doing it until you have users with
terminals, rather than teletypes. For batch work you might as well use
IO wait to context switch, or co-operative multitasking.
And the idea of a computer with a CRT and keyboard is a late 60s early
70s one.
--
Ineptocracy
(in-ep-toc’-ra-cy) – a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.
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