From: Spiro Trikaliotis (ml-cbmhackers_at_trikaliotis.net)
Date: 2005-04-23 19:39:36
Hello Ruud,
* On Tue, Apr 19, 2005 at 02:26:53PM +0200 Baltissen, GJPAA (Ruud) wrote:
> > maybe Ruud Baltissen can be asked about the gory technical details)
>
> It is always said that, theoretically, all C64 version should behave the
> same. But I also found out that the CP/M cart isn't accepted by all C64's.
> The only official differences I know of is that the behaviour of the VIC
> chip can be different for some versions.
According to http://www.floodgap.com/retrobits/ckb/display.cgi?491, Bild
Herd itself told:
"The Z80/CPM cartridge didn't work on all C64's, no-one had really
taken the time to figure out why. Someone noticed that a certain
brand of the address buffer used in the CPM cart worked better than
others so someone concluded that it must be the timing parameters
that made a difference. This wasn't true, it was a very subtle
problem that dealt with the way the 6502, the Z80 and the DRAM had
been interlaced together. So here we had a CPM cart that didn't work
with all C64's and it worked even less reliably with the C128 even
though the timing parameters in the C128 were far better. In my
opinion you couldn't call the C128 compatible with the CPM cart as
it only ran 20% of the time when tested overnight."
Thus, according to him, it is not a (direct?) timing issue. I don't know
if your suggestion about having a "spike" on PHI2 falls into the "not a
timing issue" area. ;-)
Regards,
Spiro.
--
Spiro R. Trikaliotis
http://www.trikaliotis.net/
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