Posted By
MIRKOSOFT
on 2016-05-21
10:44:57
|  Re: A mathematical demo
Hi!
I'm on Plussy scene new, but I'm real 128er.
You're writting about extra CPU and Z80.
So, I'm owner of SCPU128 (one extra CPU) and CP/M cartridge (one extra CPU).
First to extra CPU:
SCPU128 at power on takes control over all and makes Z80 in C128 not accessible. So, I bought CP/M cartridge to give Z80 back to my C128 also when SCPU is active. I tested and result was surprise: Z80 in cartridge works even when is SCPU active. When anybody has only CP/M cartridge, no SCPU, it gives to C128 one 8502 and two Z80 CPUs (one in C128 and one in cartridge). It is possible also to activate external Z80 from internal Z80 directly (vice-versa not), but handling this was not yet solved. I mean NMI can be problem for Plussy, but out of theme.
Downclocking Z80 - Z80 in C128 is downclocked from 4 to 2MHz, in cartridge from 8 to 4, but effective 3MHz - reason - simple: VIC-IIe chip! VIC-IIe cannot handle also 8502's 2MHz - so stupid C64 compatibility makes C128 less powerful, but it was decision of Commodore marketing which wanted not give to C128 same fate like 264 Series. In my eyes - Plussy is great, C64 is less (please forgive me C64 fans, but it's only my opinion).
I have also one Q:
Where I can get Plussy's Expansion Port schematics, datasheets, resources and if is using very frequently?
Reason is for now secret.
Thank you.
Miro
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