Hi FOlks,
I'm working on Building a 1MB Flash Cart for the SNES but I'm running into a few issues that I would like some help resolving.
I'm using the SNES Game PCB "NBA LIVE 95", that has a 64KSRAM chip, MAD-1 Decoder, a Battery backup & two 32 Pin ROMs. And From what I understand this is in a "LoRom" Edge Connection format correct?
I removed the two on-board 32 Pin ROM chips, and I wired in two 32 Pin PLCC sockets in there place using 26 AWG wire. I realize the address lines are in parallel for both the ROMs but I was using sockets so this doubled up my wiring and soldering work I know.
This is to connect the Two ATMEL AT49F040 4Mbit FLash chips. Having the Pin hole for A19 from the board unconnected for both chips, as the Atmel chips only have up to pin A18.
http://www.digital-circuitry.com/IMAGES ... %20012.jpg
http://www.digital-circuitry.com/IMAGES ... %20009.jpg
http://www.digital-circuitry.com/IMAGES ... %20014.jpg
I can load a few 512Kb games like Super Mario World and Qbert 3 using the first ROM socket and they run without any problems. But when I tried to load the 512Kb "Super Mario Kart" or whenever I try to use the Two chip setup, splitting a 1MB ROM game into two 512Kb files and flashing them to the ATMEL chips..... nothing loads. The fact that Mario Kart didn't load is this a RAM issue?
I'm thinking that the Split ROM setup between the two chips has something to do with the Addressing connections to the MAD-1 chip correct? Due to the fact that I'm using Flash chips with different memory sizes... compared to the original ROMs that is?
I noted that with some carts that use the 74LS00 decoder, the A21 line to the decoder is swapped for A19. This is done when using a similar 4Mbit Flash chip, from what I've read. But with the MAD-1 on my NBA LIVE 95 PCB as the decoder, there are Lines from A19,A20,A21. These being Cart Edge connections 45,46,47 in the LoROM connection format. These are also connected in parallel to the ROM Address connection pins respectively... correct?
Is there some rewiring modifications that I should be making here? to allow the two AT49F040 Flash chips to work with this Board?
I hope my understanding is correct so far, If not I apologize. I'm still a NOvice at this so, any help from you SNES Masterminds would be really appreciated.
Kind Regards,
-Gerry
I'm working on Building a 1MB Flash Cart for the SNES but I'm running into a few issues that I would like some help resolving.
I'm using the SNES Game PCB "NBA LIVE 95", that has a 64KSRAM chip, MAD-1 Decoder, a Battery backup & two 32 Pin ROMs. And From what I understand this is in a "LoRom" Edge Connection format correct?
I removed the two on-board 32 Pin ROM chips, and I wired in two 32 Pin PLCC sockets in there place using 26 AWG wire. I realize the address lines are in parallel for both the ROMs but I was using sockets so this doubled up my wiring and soldering work I know.
This is to connect the Two ATMEL AT49F040 4Mbit FLash chips. Having the Pin hole for A19 from the board unconnected for both chips, as the Atmel chips only have up to pin A18.
http://www.digital-circuitry.com/IMAGES ... %20012.jpg
http://www.digital-circuitry.com/IMAGES ... %20009.jpg
http://www.digital-circuitry.com/IMAGES ... %20014.jpg
I can load a few 512Kb games like Super Mario World and Qbert 3 using the first ROM socket and they run without any problems. But when I tried to load the 512Kb "Super Mario Kart" or whenever I try to use the Two chip setup, splitting a 1MB ROM game into two 512Kb files and flashing them to the ATMEL chips..... nothing loads. The fact that Mario Kart didn't load is this a RAM issue?
I'm thinking that the Split ROM setup between the two chips has something to do with the Addressing connections to the MAD-1 chip correct? Due to the fact that I'm using Flash chips with different memory sizes... compared to the original ROMs that is?
I noted that with some carts that use the 74LS00 decoder, the A21 line to the decoder is swapped for A19. This is done when using a similar 4Mbit Flash chip, from what I've read. But with the MAD-1 on my NBA LIVE 95 PCB as the decoder, there are Lines from A19,A20,A21. These being Cart Edge connections 45,46,47 in the LoROM connection format. These are also connected in parallel to the ROM Address connection pins respectively... correct?
Is there some rewiring modifications that I should be making here? to allow the two AT49F040 Flash chips to work with this Board?
I hope my understanding is correct so far, If not I apologize. I'm still a NOvice at this so, any help from you SNES Masterminds would be really appreciated.
Kind Regards,
-Gerry