Re: A Commodore 64 Demo Programming Milestone has been reached!

From: MagerValp (
Date: 2001-12-26 16:16:39

>>>>> "TE" == eyethian  <> writes:

TE> I can force the VIC-II to fetch video matrix data to fill the %01
TE> and %10 bitpairs in the first three columns of the FLI screen
TE> under the SuperCPU. But, what about the %11 bitpair? How do I
TE> force the VIC-II to fetch colorram data to fill this bitpair? From
TE> my analysis, the video matrix data that is forced onto the first
TE> three columns of the FLI screen under the SuperCPU will also fill
TE> in the %11 bitpair and that is not the intention.

TE> Does the VIC-II chip only fetch colorram data every eight
TE> scanlines, i.e., buffering it like it does with sprite data?

The VIC-II has a 12-bit data bus. It fetches four bits from the 2114
colour ram at the same time as it fetches character data. I don't
think forcing data on that bus with the CPU is possible, but I haven't
studied the schematic.

PS: yes, please send the TMP source, that's what I use too.

    ___          .     .  .         .       . +  .         .      o   
  _|___|_   +   .  +     .     +         .   .  Per Olofsson, konstnär
    o-o    .      .     .   o         +
     -       +            +    .

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