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From: new@udel.EDU (Darren New)
Newsgroups: comp.sys.amiga
Subject: Re: Multifinder - Just the Facts, man.
Message-ID: <18420@estelle.udel.EDU>
Date: 3 May 90 15:28:44 GMT
References: <20499@boulder.Colorado.EDU> <8930@hubcap.clemson.edu> <10143@sdcc6.ucsd.edu> <43785@iuvax.cs.indiana.edu> <7416@wehi.dn.mu.oz> <1990May3.042500.18758@wam.umd.edu>
Reply-To: new@ee.udel.edu (Darren New)
Organization: University of Delaware
Lines: 34

In article <1990May3.042500.18758@wam.umd.edu> ddev@wam.umd.edu (Don DeVoe) writes:
>>This drongo doesn't know the difference between multitasking and parallel
>>processing.
>
>Tell us, just what is the difference? In a strict sense, you can't have
>(true) multitasking without multiple processors...anything else is just
>program swapping; multitasking is implicitly denied in a single processor
>system. And just what is a drongo, anyway?

The difference is this:
Multitasking is when two or more tasks are run concurrently. 
Parallel processing is when two or more tasks run simultaneously.
           (assuming you mean MIMD.  A better one may be "two or more
            instructions running concurrently.)
The difference is this:
Simultaneous means "at the same time".
Concurrent means "Another may start between the time the first starts and
   the time the first ends."

Hence, MS-DOS (ignoring TSRs...) is single processing, single tasking.

The Mac OS (under multifinder) is nonpreemptively (sp?) multitasking.

The AmigaOS is premptively multitasking and parallel processing (via Agnus).

Unix is multitasking and multiprocessing (where "process" is taken in the
computer-science sense). The difference between multiprocessing and
multitasking is the difference between a Unix process crashing and
an AmigaDOS task crashing: address spaces.  Unix processes cannot
share address spaces while AmigaDOS processes must.  (Unix shared
memory segments are shared with the kernel and are a special case
I'm ignoring here.)

I hope this clears up some terminology.   -- Darren