Ruud wrote: > > The $d700-$d7ff area is quite safe, it's free on the C128 as well. > > What about the SID in C64 ????? I have to disagree in this matter. I thought that you were talking about internal modifications. I didn't realize that you were going to tap these addresses with external decoding. But I think that $d031-$d03f would work with external decoding logic. The VIC-II will return $FF when these addresses are read or written, and the data on the bus will simply be ANDed with $FF, i.e. no effect. The only problem is that you need quite much decoding logic (to tap all 16 address lines). > Anyway this means there are only two solutions left. The first one is to > use dipswitches so you can use your own HW with as much as cartridges as > possible. But this means that you cannot use it with cartidges like FC3 > who uses both IO-lines without any further decoding. Well, you can modify e.g. the Action Replay hardware so that it will leave $de01-$deff free, and that it won't react on $de00 on read access. The cartridge has quite funny design: the control register is write-only, but it will react to any (read or write) access to $de00-$deff. I patched one Action Replay or a REU so that it'll work simultaneously with the REU connected. I think that the modification made the REU registers write-only. Of course this doesn't work with any software that tries to read the REU registers, but with prlink it does. Marko
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