Apple IIgs ramsize issues

[gorlik]

Apple IIgs ramsize is missing 128K in almost all configurations.

The issue is that ramsize considers the total amount of RAM in the system including the 128K of "slow memory".
i.e. specifying 8M results in 128K + 8064K of fast RAM (mapped in banks 00 to 7D). In a real apple IIgs with a 8MB ram expansion the fast RAM should be 8192K mapped in banks 00 to 7F.

the missing 128K affect all configurations (including the default)

there are at least 3 possible fixes to the issue:
1- Ignore "slow ram" in the ramsize. Likely the simplest fix, but might not be totally correct in terms of documentation.
2- allow any multiple of 64KB for ramsize and let the user decide (expansions of odd sizes are uncommon but the real HW will detect them properly)
3- change ramsize meaning into "ram expansion" that adds to the base memory of the system.

I'll be happy to help with a patch but I'd like to hear the developes opinion on the best way to fix the issue.
thanks!

[rb6502]

I assume the sizes are only wrong on ROM 03, they're correct on the ROM 01 driver apple2gsr1?

[gorlik]

the sizes are odd for ROM1 as well.
mame apple2gs -ramsize 2M -> 896K of expansion memory mapped from bank 0x10 to 0x1D
mame apple2gsr1 -ramsize 2M -> 1792K of expansion memory mapped from bank 0x02 to 0x1D

assuming ramsize means expansion memory (option 3 in my original post) the correct behavior should be:
mame apple2gs -ramsize 2M -> 2048K of expansion memory from bank 0x10 to 0x2F (total fast RAM 3072K + 128K of slow ram)
mame apple2gsr1 -ramsize 2M -> 2048K of expansion memory from bank 0x02 to 0x21 (total fast RAM 2176K + 128K slow ram)

[rb6502]

Thanks, I've resolved this with option 1 (don't include the slow RAM in E0/E1 in -ramsize), which isn't exactly right but makes sense within the architecture of the machine.