🚀 go-pugleaf

In article <76000290@p.cs.uiuc.edu> gillies@p.cs.uiuc.edu writes:
>
>The sad thing is, the vast majority of Macintoshes in this world
>cannot support virtual memory.  This is because the 68000 chip has a
>design flaw that doesn't allow virtual memory to be implemented.
        ----
>....
>
>Don Gillies, Dept. of Computer Science, University of Illinois
>ARPA: gillies@cs.uiuc.edu   UUCP: {uunet,ihnp4,harvard}!uiucdcs!gillies

I have to take exception to this statement. This is like saying that Henry
Ford's Model T was flawed since it didn't have an 8 cylinder engine and
mechanical air conditioning (opening the windows doesn't count :>)). In 1979
when the 68000 was first introduced, it was the largest commercially produced
die ever attempted by man. For the first time, we were given internal 32-bit
MPU features while the rest of the world was still thinking 8-bits.  We were
given a large number of general purpose registers while the rest of the world
still had to struggle with dedicated registers. After Motorola
**sucessfully** began producing the 68000, the designers went back to the
drawing tables and started adding extra features: full virtaul memory and
virtual machine suport and loop mode in the 68010; 32-bit ALU's, on-chip
instruction cache, and full 32-bit external bus support in the 68020; on-chip
data cache, on-chip paged MMU, synchronous bus, burst mode, and on-chip
Harvard architecture in the 68030.  The Motorola High End design team
has spent the last 9 years carefully executing a plan to give the user
community the highest possible performance given a moving fabrication
technology target. I don't know why Apple chose to use the 68000 in the
original toaster Mac's rather than the 68010, but I would assume that it
had a lot to do with pricing.
  Motorola took a huge gamble introducing a microprocessor which broke with
the industry convention (set by Intel) of always introducing MPUs that were
completely compatible with existing families (8080-->80188-->80186-->80286-->
80386-->... vs 6800-->6801-->6805-->68HC11 ||| 68000-->68010-->68020-->68030
-->680x0-->...).  I think most readers of this group would agree that Motorola
made the right choice in this respect.  Let's quit talking about the "flawed"
68000 (or 67999 as one poster stated a few months ago), and just be glad
that Motorola has given us what we all wanted...a very high performance,
orthogonal, easy to program, upward compatible MPU family that is STILL the
metric by which most, if not all, other microprocessors are judged.
 _____________________________________________________________________________
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|tomj@oakhill.UUCP		Tom Johnson				      |
|(512)440-2143			Motorola High-End Marketing		      |
|				Austin, TX				      |
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