Date   : Tue, 27 Apr 2004 18:55:45 +0100
From   : "Dom Wright" <domwright@...>
Subject: Re: 65c02

John Kortink Wrote:

>On Tue, 27 Apr 2004 16:30:45 +0100, Dom Wright wrote:

[...]
>>
>>I've just dug out an Issue 7 machine and put a 65c02 in it and it seems
>>to work fine.
>>
>>>Must be some electronic incompatibility, most likely bus
>>>timing or interrupt related. Manufacturer might also be
>>>a factor in this context (this one is a GCE).
>>
>>What do I look for on the board to check this?
>
>I meant the manufacturer of the 65C02. Look at
>the chip's markings. I meant GTE, not GCE by the
>way. I think the one that worked back then (for
>me) was a Rockwell.

Oh, I see.
It's about time I replaced my brain with one that worked ;-)

This chip is a Rockwell too - R65C02P2

One thing I did notice when I used to use this machine was that
the 65C02 caused problems when used with a Teletext adaptor.
The adaptor seemed to work, but the signal quality was so bad
that anything I downloaded had 90%+ corruption.

Switching back to a normal 6502 fixed it.  Has anyone any
ideas why this would be?  (I don't use this system anymore
but I am curious as to whay the cpu would have this effect.
My guess is bus timings).

Dom