Path: utzoo!attcan!uunet!seismo!sundc!pitstop!sun!amdcad!weitek!dms!albaugh
From: albaugh@dms.UUCP (Mike Albaugh)
Newsgroups: comp.sys.mac
Subject: Re: When will MacOS get virtual memory?
Message-ID: <551@dms.UUCP>
Date: 6 Oct 88 18:37:31 GMT
References: <1526@oakhill.UUCP>
Organization: Atari Games Inc., Milpitas, CA
Lines: 70

From article <1526@oakhill.UUCP>, by tomj@oakhill.UUCP (Tom Johnson):
> 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.
>         ----
> 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

	Only if Henry had provided 8 cylinders and only put pistons in
four of them :-). Seriously, If the 68000 had not `tried' to do virtual
memory, by saving almost_but_not_quite enough information on a bus_err, would
I accept this analogy

> [much horn-tooting deleted]

> 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.

	Maybe they were smarter than me, and didn't believe the moto
salesman's swear_on_a_stack_of_bibles (did I forget to mention I'm an
atheist) spiel that the the 010 would always be a SMALL (no, I'm not
gonna state it publicly) increment more expensive than the 000.

>   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"

	Maybe it had something to do with lack of installed base? Sure, I'll
agree they made the right choice moving _from_ the 6800. I may wish to
reserve judgement on moving _to_ the 68000.

> 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
                                                    ^^^^^^1^^^^^^^^
> orthogonal, easy to program, upward compatible MPU family that is STILL the
   ^^^^2^^^   ^^^^^^3^^^^^^^^  ^^^^^^^^4^^^^^^^
> metric by which most, if not all, other microprocessors are judged.

	That's what I wanted, all right, but anyone who uses 2 & 3 above
with a straight face must be a sales-rep, not a programmer, 1 is open
to discussion, and 4 can be readily refuted by anyone who has had to
move code they didn't write from 68000->68010 (traps and MOVE xxx,SR come
immediately to mind)

>  _____________________________________________________________________________
> |Disclaimer:  The views stated above are my own and do not necessarily	      |
> |             reflect the views of Motorola.				      |
> |									      |
> |tomj@oakhill.UUCP		Tom Johnson				      |
> |(512)440-2143			Motorola High-End Marketing		      |
> |				Austin, TX				      |
> |_____________________________________________________________________________|

Disclaimer: I use 68010's and 68000's all the time, in embedded systems.
	(I use a 68020 in my accelerated Mac SE). I do so because they
	are cheap and fast, not because I have any delusions about
	technological superiority. The `cheap' part has more to do
	with Apple and Atari (the other one) using them than anything
	else.

| Mike Albaugh (albaugh@dms.UUCP || {...decwrl!turtlevax!}weitek!dms!albaugh)
| Atari Games Corp (Arcade Games, no relation to the makers of the ST)
| 675 Sycamore Dr. Milpitas, CA 95035		voice: (408)434-1709
| The opinions expressed are my own (Boy, are they ever)