Could sram high score save be hacked into roms?

[tomwaits]

Sorry if this has been discussed before, but would it be possible to hack high score saving into roms for play on the Everdrive?

Lots of Genesis games save high score tables while playing and lose the scores with power off. Would it be possible to hack the roms to re-route high score table read/write from an address range in console ram to an address range in sram? It looks like you'd need to change some header bytes that flag whether sram exists, then need to find/change the address range where the high score table is being accessed during play? Would probably also need to make a base high score sram file since it would be un-initialized garbage. Is there any other technical problem beyond finding the correct address ranges to hack in the rom?

I know there's an eeprom->SRAM save hack for Wily Wars, but would it be possible to hack SRAM into games that never had save memory? Has this already been done for any games?

[TmEE]

its certainly possible to make non SRAM games to work with SRAM, but you got to find someone willing to hack the games... in the most optimal case, it would be as easy as moving the RAM stuff where high scores are into SRAM area.

[SEGAretro]

its certainly possible to make non SRAM games to work with SRAM, but you got to find someone willing to hack the games... in the most optimal case, it would be as easy as moving the RAM stuff where high scores are into SRAM area.

But you would also have to find out for every game at what address the high scores are stored...

I guess it should be some kind of 'list' with Game Title/Product ID/Address/Length which could be updated (to add new games) just like updating the Everdrive OS?

Examples:

ROM Header Game Title: STREET FIGHTER‡U'SPECIAL CHAMPION EDITION
Product ID: GM MK-1090 -00
Address: FFFE12
Length: 48

Game Title: SUPER STREET FIGHTER2 The New Challengers
Product ID: GM MK-12056-00
Address: FFFCB4
Length: 48

[SEGAretro]

Nah not for every game, just the ones that are so good you want to try to get a high score. :)

And shouldn't it be really simple to find out the area in memory where they are? Just search for your name/initials or score. Does the Mega Drive Action Replay have a machine language monitor like the C64 AR that would let you do that? Some emulators probably do.

That's how I found those addresses, by using an emulator :)