RE: Screen memory mapping VIC-20

Hallo Marko,


> You could also type some POKEs after RESET to "downgrade to unexpanded" while having a 3k or 8k+ RAM expansion plugged in.

That rang the bell, I indeed missed something. The first thing the cartridge does is programming the VIC chip. And it does it by using the standard values, read: the values for an unexpanded VIC. Thank you!

But there is still another small mystery: the cartridge writes several times a value to $9800 aka I/O block 2. But the cartridge doesn't contain any I/O at all. But as said: only write actions. Maybe some I/O was foreseen but not implemented?


Met vriendelijke groet / With kind regards, Ruud Baltissen

www.Baltissen.org



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