Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!cornell!uw-beaver!tektronix!reed!kamath
From: kamath@reed.UUCP (Sean Kamath)
Newsgroups: comp.sys.apple
Subject: Re: Zip Chip Question.
Message-ID: <10386@reed.UUCP>
Date: 21 Sep 88 01:23:52 GMT
References: 
Reply-To: kamath@reed.UUCP (Sean Kamath)
Organization: Reed College, Portland OR
Lines: 54

In article  tmetro@lynx.northeastern.EDU writes:
>No. The No-Slot-Clock (manufactured by Dallas Semiconductor - dst. by
>SMT) has its own internal frequency reference. Besides the Zip Chip's
>method of acceleration does not affect the system clock or speed external
>to the CPU.

True enough, but, as stated previously, if it happens to cache in the wrong
place, it will destroy the "wakeup" sequnce on the a0 line. (or is it the a4
line?)

>Be warned that the No-Slot-Clock may not work with the Zip Chip for other
>(yet unknown) reasons. I have a No-Slot-Clock installed in my //c which
>does not opperate when I have a W65C802 CPU installed in place of the 65C02.
>Western design Center (creator of the 65C802/816) is looking into the
>problem.

Yes, I had the same problem.  I don't think it is "anyone's" fault.  By that
I mean I talked to SMT (Who at the time had just hired a mr. Sanders of
"Understanding the Apple . . ." fame.) and they had not a clue as to what
was wrong.  Timing chart *are* just a bit off, but:

It works just fine in micro #2 with a 65802 in it.  Soooooo...


I think it's your MMU.

"Huh?" he grunts.

I have looked and looked, but nowhere have I found documentation on it:
Appearantly (Dennis Domms told me this at the last applefest), a few of the
MMU's in the //e's were a little screwy.  They could cause timing errors.
Since the MMU is directly responsible for handling the R\W line, this
*might* be the problem.  Since I can't get any docs on this "bug", all I can
say is: Try another MMU.  Maybe it'll work.  If it *does*, then PLEASE send
me the stuff (i.e. part number and all that) for the chip, we can compare it
to mine, and issue a "warning" about this.


> Tom Metro


Sean Kamath

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