Hi Terry,
I just ran across your blog entry on fixing up the C4P for the retrocomputing challenge. Apologies on the red break key thing - I meant to mention that! Anyway - awesome work on the C4P MF. I honestly wasn't too sure what it was - With the drive it seemed like a 4P MF not a 4P...
ANyway it looks like you did AWESOME work on the 4P MF!.
A quick note on one useful 'hack' on the color ram:
Way back in the day I remember realizing that since the scroll command in BASIC only scrolled the video ram and not the color RAM - you could effectively give yourself a reverse video screen - by just writing values to the color ram... I.e. 'Software inverse video'. In those days I didn't have a color display I just used a mono display but it did provide a 'white background with black text'...
It's been too long but something along the lines of:
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5 POKE 56832,5:REM Turn on color? Did I turn on sound too?
10 V=53248:REM video ram base ($D000 ???)
20 C=V+4096:REM color ram base
30 FOR I=C to C+2047: REM 2K of 4 bits
40 POKE I,240:REM set high nybble to white, low nybble to black
50 NEXT I
I almost certainly have the high nybble value wrong there... I don't have the OSI manuals infront of me - its all from 20+ years old memory...
Anyway - first off so glad to see you got good use of the C4P and it went to a better home than I could have imagined. Nice one on the demo code too - really brought back memories...
Cheers,
Pete