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From: mrc@Tomobiki-Cho.CAC.Washington.EDU (Mark Crispin)
Newsgroups: comp.sys.mac,comp.sys.next
Subject: Re: The NeXT and the Mac
Message-ID: <5142@blake.acs.washington.edu>
Date: 22 Dec 89 22:02:34 GMT
References: <5094@blake.acs.washington.edu> <9138@cbmvax.commodore.com>
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In article <9138@cbmvax.commodore.com> daveh@cbmvax.commodore.com (Dave Haynie) writes:
>Actually, you can't call the NeXT "multi-processing" yet either, though of
>course Mach supports multi-processing.  But, unless you count running the
>68030 at the same time as the 56000, you're single processing on any NeXT
>that NeXT is currently talking about.  
>
>However, you are really multitasking.  With friendly applications on the
>Mac, you're really multitasking too.  The big difference with a system
>like the NeXT, designed for multitasking (like all UNIXs), is that you never
>waste CPU time sitting in a task that's waiting for some external event,
>while you certainly can under Multifinder.  And of course, you've got
>real IPC on the NeXT.

Foo.

By your definition mainframe timesharing systems are "multitasking"
and not "multiprocessing".

In the past 20 years that I've been involved with computing,
"multitasking" has referred to facilities where you could dynamically
load programs as more or less cooperating co-routines into a
single-processing computer.  Generally, there is only a single address
space; programs are relocatable (via a base register) and must be
careful not to step out of its memory bounds.

In the case of multi-processing, each program runs in its own virtual
machine.  Memory relocation and protection is generally done in
hardware.  Process control is handled via scheduling based on time
quanta instead of voluntary relenquishment via a co-routine call.

Internally, most operating system kernels are multi-tasking (e.g.
between scheduling, interrupt servers, etc.), but present a
multi-processing environment to the user-level programmer.

And anyway, what's all this Amiga junk doing on comp.sys.next anyway?
The Amiga has even less to do with this newsgroup than the Mac does.
At least the Mac and the NeXT have some overlap in their customer
base.  Why not go back and hash it out against the Atari ST?

Mark Crispin / 6158 Lariat Loop NE / Bainbridge Island, WA 98110-2098
mrc@CAC.Washington.EDU -- MRC@PANDA.PANDA.COM -- (206) 842-2385
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