Sega Saturn Internal Memory Mod with FRAM – no battery required
@SegaSaturn
Published in
SegaSaturn
· 3 years ago
... xcept for one pin. The UPD43257B has an active-high CE signal on pin 22 (driven by signal SCE2 on the schematic) whereas the FM1808 has an active-low #OE signal on pin 22. Tracing back the SCE2 on the Sega Saturn Schematics I found that it is originating from a battery management IC. This type of chip usually prevents bad writes during power down cycles. Clearly, this signal would not be necessary for the proper operation of the FM1808. So how to address the #OE signal issue on FM1808? #WE Controlled Timing Looking at the Saturn’s BRAM schematic more carefully, you’ll notice that it operates with only 2 control signals: SRAMCE and MWR. Inspectin ...