Allow C64 CP/M Cartridge also for x128
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#240 Allow C64 CP/M Cartridge also for x128
Hi!
I saw in VICE-Emu SVN History that CP/M cartridge was applied to x64 and x64sc.
I'm real 128er and it can be great to test it with x128 - you're sure asking "What a stupidity?!"
I own 128DCR with SCPU128. Everybody knows that SCPU and it's CPU WDC65816 takes control over all and if I want to use Z80 code or CP/M I must to turn it off 'cause it's impossible to reach CPU switch 8502 to Z80.
In all cases 64 mode of C128 disables Z80 CPU totally and it can be great to allow 128 mode work with 128's Z80 and 64 mode work with cartridge Z80...also 128's Z80 Is downclocked to 2MHz for VIC-IIe sync, so also here will be possible to test difference of speed...and compare fast serial... think about and maybe do it.
I mean if is possible to emulate cartridge for x64 and x64sc, it can to be possible for x128.
I know that e.g. SCPU64 with C128 jumps directly to 64 mode, maybe do the same CP/M cartridge.
Experiments and comparing is best way how VICE helps me and I mean many others.
Miro
does the real cp/m cartridge even work with a real c128? IMHO it would have needed a similar "hack" as the scpu (some socket/adapter on the mmu)
Take a look:
Really never owned CP/M cartridge, but about hack:
C64 has no MMU - so needs not hack like SCPU128. MMU in C128 manages memory config (of course MMU = Memory Management Unit), but also CPU selection.
If C64 is missing MMU then switch to Z80 mode must to be by other way, like 80 column cards or so.
And when is possible to switch CPU without MMU it's accessible no matter of connected SCPU.
Of course we know that C128 in use SCPU64 works differently like with SCPU128.
SCPU64 performs direct jump to C64 mode, maybe CP/M cartridge does the same...
My dream is get CP/M cartridge and allow work in Z80 mode with enabled SCPU128.
CP/M cartridge is really rare, if it will work I buy one and results can share also with VICE team...
So, still it looks too personal wish, but really boys, it can open new door to programming C128 w/SCPU... maybe you plan in future emulation of SCPU128...
And I mean that code for x64 and x64sc is applicable with changes to x128.
Miro
According to Bil Herd, the CP/M cart. was a "rush job" and a hack. It was tuned to work with the early revisions of the model 64. It doesn't work with later revisions.
I doubt that it can work with the SuperCPU or the model 128.
I did an experiment on x128 with the cp/m cart. As soon as the bios loads into address $ff00, the mmu changes the memory configuration and the cpu jams.
So unless some-1 can show me / provide me the hardware/software hacks that are needed to make it work on a c128, the cp/m cartridge will be x64(sc) only.
Ok, newer FReq #250 was closed as invalid for this one.
This FReq if I remember correctly also marked as invalid.
For now: I'm owner of Commodore 128DCR, SuperCPU128 and CP/M cartridge - all works!
If is SCPU turned off I have available MOS8502 and two Z80 CPUs (one inside C128, one inside cartridge), can run CP/M 3.0 and in 64 mode CP/M 2.2, internal Z80 can direct switch to external Z80, vice versa not.
When is SCPU turned on I have available 65816 and Z80 inside cartridge. Works correctly only at switch must to be SCPU in slow mode, in other situation by choice slow/fast. Internal Z80 is unavailable when is SCPU turned on, lines are linked directly to 8502 and 65816 replaces it and make self active... So, again marking this FReq as invalid will be not fair. And I mean that situation is same in case emulation SCPU64 - so add CP/M cartridge to x128 and xscpu64.
Thank you for reading these lines and understanding.
Miro
Will be this feature request anytime processed?
Thank you for answer.
Miro
maybe, maybe not. there are about a million more important things to fix/add/support.