On Tue, 25 Sep 2001, Ruud Baltissen wrote:
> It is a shame to have so much power at hand and then not being able to use
> it. This brings me to an old idea: replace the C128 EPROMs with C64 ones
> that have been altered slightly because of the MMU at $FF00. This would mean
> that one has complete control of the MMU, including the banks, even in
> C64-mode.
That idea wouldn't work very well, since the LORAM, HIRAM and CHAREN bits
work in a totally different (and in my opinion, more logical way) in the
C128 mode. One of the LORAM and HIRAM bits selects the color memory bank
(two banks of $d800-$dbff) for the CPU and the other selects it for the
VIC-IIe, and the CHAREN bit selects whether the character ROM is enabled
in the VIC-IIe memory space. In the C64 mode, there is only one bank of
color memory, and the character ROM is constantly enabled in two of the
VIC-IIe banks ($0000-$3fff and $8000-$bfff).
Marko
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