Can the game code modify PRG rom?

Nadia · Post by **Nadia** » Tue Dec 08, 2009 12:26 am

Can the game code(in PRG ROM) write to local storage? i.e. Can the code use local variables which point to memory within the PRG rom memory area? e.g using counters etc. defined inside the program itself...

Dwedit · Post by **Dwedit** » Tue Dec 08, 2009 12:41 am

ROM is not writable.

tokumaru · Post by **tokumaru** » Tue Dec 08, 2009 3:19 am

Writes to PRG-ROM often cause the written value to be used by the mapper, if one is present. PRG-ROM stays intact of course, being ROM and all.

doppelganger · Post by **doppelganger** » Tue Dec 08, 2009 6:45 am

One could, in theory, have RAM mapped into $8000-$ffff, but in practice external RAM, if any, is usually mapped into $6000-$7fff.

Post by **tepples** » Tue Dec 08, 2009 9:03 am

Except, of course, for one well-known Japan-only mapper that has ROM at $E000-$FFFF that's identical in all games, RAM at $6000-$DFFF, and a rewritable magnetic medium.

Jeroen · Post by **Jeroen** » Tue Dec 08, 2009 12:36 pm

You COULD just say famicom disk system you know

Post by **Memblers** » Tue Dec 08, 2009 1:32 pm

My Squeedo cartridge uses 29F-series FlashROM there. It would be nice if that were emulated, because of the obvious advantages over EPROM. It wouldn't be that hard to emulate, but there are a couple basic different types.

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Can the game code modify PRG rom?

Can the game code modify PRG rom?

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