Path: utzoo!mnetor!uunet!husc6!uwvax!puff!richardk
From: richardk@puff.cs.wisc.edu (Richard Kottke)
Newsgroups: comp.sys.m68k
Subject: Re: Apollo/Sun 68000,68010,68020
Message-ID: <1525@puff.cs.wisc.edu>
Date: 30 Mar 88 16:52:34 GMT
References: <3b219db7.d858@apollo.uucp> <903@cayman.COM>
Reply-To: richardk@puff.WISC.EDU (Richard Kottke)
Organization: U of Wisconsin CS Dept
Lines: 23

In article <903@cayman.COM> brad@cayman.COM (Brad Parker) writes:
>From article <3b219db7.d858@apollo.uucp>, by heinzl_c@apollo.uucp (Carl Heinzl):
>> 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
>
>No doubt 600 others will also respond to this. The issue here is not
>preemptive multitasking ("What bubba meant to say was...") The issue
>here is recovering from a bus error. The demand paging support (read

  Recovering from a bus error is a problem only if the system uses a virtual
memory scheme (which it would if it was running UN*X.)  If the system was
running, say, OS-9/68k, then virtual memory is not required and the bus error
is a real bus error, not a flag indicating that a new page needs to be brought
in.
  Since it is not hard to port a UN*X application to OS-9 (especially if its
in C), OS-9/68k was an obvious choice when only the 68000 was available.  So
why didn't anyone base a machine on it?  I dunno.
  It seems like the history of computers shows the hardware designer making
faster machines with bigger memory, and the computer scientist making compilers
and operating systems to bring the speed back down to a PDP-8.  The only
advantage is that it becomes easier and faster to code more complex programs.
Will it ever end?