Re: C64 CP/M Cartridge

From: Richard Atkinson (
Date: 2000-03-20 21:02:33

On Mon, 20 Mar 2000, Nicolas Welte wrote:

> I always wondered if there are different versions of the CP/M cartridge
> for PAL and NTSC systems. After all the timing between these two differs
> much more than between any revision with the same video system.

'Timing' here refers to the nature of the signal waveforms on each
individual clock pulse; not the number of clock pulses per line / frame /

I think it's about time cbm-hackers looked into what can be done to the
CP/M cartridge to make it compatible with all C64s. I see it not as a CP/M
cartridge but a general purpose Z80 second processor, and I'd like to be
able to run ported ZX Spectrum code on a C64 with CP/M cartridge or a
C128. An example of this might be the music routine from a 128K Spectrum
game; having extracted the routine and trapped all the OUT instructions
that wrote to the Spectrum sound chip, it could run on a Commodore machine
and output a list of the sound chip registers and their updated
contents. Then a generic 6502-based conversion utility could translate all
the Spectrum sound chip register values into equivalent SID writes.

I think if we work from the assumption that it is the CP/M cartridge that
is at fault and needs changing, then there could eventually be a quick
hack for the relatively small number of them out there, to allow them to
run on all C64s (including C64Cs). I wonder if Bil Herd recalls the nature
of the problem with the CP/M cartridge.


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