eslapion wrote:This is probably for compatibility with self modifying code cartridges but as demonstrated with the game Crazy Antics, you MUST place in read-only mode ALL the RAM for full compatibility with dumped cartridges.
I had to try this out.
With the NTSC dump on zimmers, I could successfully run K-razy Antiks only with BLK3 and BLK5 attached as ROMs (in RAM, it bombs out as you wrote), but at least I could fill BLK1, BLK2 and $0400..$0FFF with writable RAM without the game mucking up.
There are some games, notably Bug Crusher, which won't run alongside a +8K (or more) RAM expansion, as they don't initialise the screen correctly - they rely on the screen being at $1E00 but still execute that part of the KERNAL reset routine which ultimately puts the screen base at $1000 because of the RAM expansion present at BLK1.
My VFLI mod however leaves the screen base at $1E00 regardless when there's no other external RAM expansion attached, and I still have to see an example game cartridge which 'complains' about the extra RAM at $0400..$0FFF.