Path: utzoo!mnetor!uunet!husc6!mit-eddie!apollo!heinzl_c
From: heinzl_c@apollo.uucp (Carl Heinzl)
Newsgroups: comp.sys.m68k
Subject: Apollo/Sun 68000,68010,68020
Message-ID: <3b219db7.d858@apollo.uucp>
Date: 28 Mar 88 23:32:00 GMT
References: <7656@apple.Apple.Com> <7670@apple.Apple.Com> <7681@agate.BERKELEY.EDU> <215@ditka.UUCP>
Organization: Apollo Computer, Chelmsford, Mass.
Lines: 41

>><I think one point you are both missing out on is that preemptive multitasking
>><requires hardware support not available on a 68000.
>>
>>Right. So how did Sun, Apollo, Amiga, Sage, Stride and a multitude of
>>others manage to market 68000 systems that did preemptive
>>multitasking?
>
>Neither Sun nor Apollo ever marketed systems based on the 68000,
>to the best of my knowledge.  The Sun-2 uses a 68010, while the
>Sun-3 family uses a 68020.  Likewise, I believe Apollo's are
>based on these processors (larger models now use some custom
>stuff) and not the vanilla 68000.

This is incorrect.  Apollo DN600 (do not confuse with DN660), 400 and 420
are all 68000 based machines.  They use an arrangement of Dual 68000
cpus to allow preemptive multitasking.  Basically, one of the processors
does the error handling when a page fault is taken while the other
preserve machine state (making it restartable).

I also believe that the SUN model 1 series use dual 68000 cpus.  The
model 2 series was 68010 based and now their model 3's are 68020.

>
>Not that this implies that multi-tasking is impossible on the
>68000.  The Amiga is a prime counter example.
>
>-- 
>Karl Swartz		|UUCP	decvax!formtek!ditka!kls
>1-412/937-4930 office	|	{floyd,pitt,psuvax1}!idis!formtek!ditka!kls
>			|BIX	kswartz
>"I never let my schooling get in the way of my education."  (Twain)
>

Carl G. Heinzl  apollo.UUCP
(617) 256-6600 x 7153

____________   ____/--\____ 
\______  ___) (   _    ____)     "Damn it Jim!,
     __| |____/  / `--'            I'm a programmer not a Doctor!"   
     )           `|=(-
     \------------'