Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!jarthur!nntp-server.caltech.edu!toddpw
From: toddpw@nntp-server.caltech.edu (Todd P. Whitesel)
Newsgroups: comp.sys.apple2
Subject: Apology to Randy Hyde (was Re: my decision for the LC)
Message-ID: <1991Feb16.053155.8278@nntp-server.caltech.edu>
Date: 16 Feb 91 05:31:55 GMT
References: <12052@ucrmath.ucr.edu>
Organization: California Institute of Technology, Pasadena
Lines: 72

rhyde@koufax.ucr.edu (randy hyde) writes:

>  From this standpoint I guess you could claim that the 6502's
>instruction set "prefers" an eight-bit bus.

Gee, that was my point... 'prefers' is a sort of metaphor to avoid lengthy
explanation, like chemists saying that electrons 'prefer' to be in certain
orbitals.

>going to a 16 or 32-bit bus would provide very little in the way of
>performance improvement!
> After discussing this with Mr. Mensch, He led me to believe a 16-bit access
>would still take 5 cycles, even on a 16-bit bus. This is lousy microcode

I'll say it is. I agree with Mensch when it comes to simplicity in the
instruction set, but using brain-dead microcode on a wide bus is idiotic.
The 80386 does 32 bit reads into a byte wide instruction pipeline, which
strikes me as a fairly simple (if slightly nondeterministic) and elegant
way to handle a byte oriented instruction stream on a wide bus.

>the chip, using modern design techniques, could run much faster than an
>equivalently clocked 65c816.

I don't doubt that. I felt that you were really designing your own CPU using
concepts from the 65816 (and heavily borrowing from the 68000) so you might
as well call it a new CPU entirely. This is what I didn't like about your
article and I am sorry for saying 'disgusted' because that really is too
loaded a word to describe my opinion of it. I felt that the 65820 idea was
a 68000 wanna-be and that what you were really talking about was a bank
switch between a 6502 and a 68000 -- which is inappropriate to the goal
of improving the 65816 rather than replacing it entirely.

>Of course the whole discussion is a moot point since this chip will
>never exist.

True. The 65832 might, however, and if Mensch actually does a competent job
of it then it will remain true to the philosophy that makes it one of the best
lightweight controller chips.

>But since my design "disgusts" you, why don't *YOU* write an article
>describing something which is better.

(1) I haven't figured it all out yet.
(2) I am still a Junior in college and not comfy in a research job.
(3) My free time is almost entirely absorbed in cranking out GS stuff some of
which will finally be releasable in a week or so, and none too soon because I
need the money.

> Quite honestly, the only way you're going to convince us otherwise is to
> actually write the code.  In other words, "put up or shut up."
> You claim a decent compiler can be written for the GS. I've yet to see it.
> Prove me wrong.  Prove a good compiler can be written, write it!

Dammit, I'm only human and I'm far from independently wealthy! A compiler is
a pretty tough project for one person (although I am taking a class on
programming paradigms and compilers next term). When I get it working, I'll
post it. But it'll probably have to wait until the GIFfer and the PostScript
downloader have real interfaces, and the subtitler and chatter are written,
and the TCP/IP code is functional...

[lots of decreasingly objective stuff deleted]

> it's another thing to call my work disgusting.

Yes, it is. I really shouldn't have said that.

I wish to formally apologize for calling the 65820 paper "disgusting". It was
an inappropriate word to use and did not properly reflect my differences with
the 65820 design.

Todd Whitesel
toddpw @ tybalt.caltech.edu