Hi-Rom 64mb single rom

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tsop48
Posts: 5
Joined: Wed Apr 13, 2022 5:33 am

Hi-Rom 64mb single rom

Post by tsop48 »

Hello there , im recently start making my own snes carts , i know that almost all snes carts use only 32mb rom max size ,and 48 mb rom into 2 roms , but the bus have pin for a22 , i try to make a umk3 hacked game that use 64mb , the game doesnt run with a single rom , is there a modification needed to run a game like this ? i try the same excercise in a aliexpress 128mb single rom board and it works ,but with an original board not.
tepples
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Re: Hi-Rom 64mb single rom

Post by tepples »

LoROM: CPU to ROM connection skips CPU A15
HiROM and ExHiROM: CPU to ROM connection skips CPU A22

If you are making an ExHiROM (mode $25/$35) on one 8Mx8 flash chip, connect CPU A23 from the cart edge to PRG ROM A22. Keep in mind that the .sfc ROM format stores ExHiROM with the $C00000-$FFFFFF data first, so you'll probably need to reorder the data that you burn to the chip so that the first 4 MiB of the ROM file lands in the second 4 MiB of the chip.
tsop48
Posts: 5
Joined: Wed Apr 13, 2022 5:33 am

Re: Hi-Rom 64mb single rom

Post by tsop48 »

Thanks for the tip , it doesnt work with the umk3 hack , but with the tales of phantasia work flawless .
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