I designed a 8Mo cart with SEGA mapper, using the logic sheme of Megavolt.
I am trying to build a cart with FRAM, but i can't achieve to make it working.
I already made a pcd for 4Mo games and i made SRAM works using a 74HC74 and 74HC139 couple to select the rom or the ram chip (using TIME and D0 signals)
Obviously, this does not work with the SEGA mapper and i can't figure why.
The cart works perfectly for standard game (Tested with SSFII) but if i try to use with the SRAM hack, it seems that the mapper does not work anymore because the screen is glitched.
Is there anybody to help?
i'll try to post capture of my schematics