Increasing ROM size?

Door spencerelliott

Supporter (2)

afbeelding van spencerelliott

10-05-2022, 20:01

Hello all, I am starting my MSX2 development adventure and I am playing around with modifying this disassembled version of Metal Gear. After calculating how much space is left across banks 0-F in the MegaROM mapper, there is only 1.17KB available. It would be nice to increase this amount, if possible. Is there any way that I could use a different mapper or anything to get more ROM space or is it not possible? Any help would be greatly appreciated!

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Van Metalion

Paragon (1509)

afbeelding van Metalion

10-05-2022, 20:50

Of course it's possible.
You can keep the Konami SCC mapper, and increase the rom size up to 512Kb.
Beware that you will need to have (2^n) pages, so your choice is either 256Kb or 512Kb.

Van spencerelliott

Supporter (2)

afbeelding van spencerelliott

10-05-2022, 22:02

Thanks Metalion. All I did was create empty banks that go from 0x10-0x1F so that the ROM is padded to 256KB for now. Is that all I need to do and I can switch between the banks by setting the appropriate mapper bank? The 256KB ROM I generated was able to boot on openMSX without issues so I'm assuming it's working as intended.