I have an NTSC prototype of a game that was never released in NTSC countries which came to me chip-only. I want to demonstrate it working in an actual NES when it comes time to sell it. I have dumped it and the dump works on both in emulation and on a real NES.
The thing is, the proto came on a Toshiba TC571001D EPROM, which uses a maskROM pinout as opposed to the usual EPROM pinout (TC571000D - shares the same datasheet). It's a CHR RAM SNROM game so popping this chip into a SNROM cart should be a pretty straight-forward affair... even more so than most protos.
First, I made an adapter so that I could dump it in my EPROM programmer. This worked and resulted in a dump of the games that worked on emulators and original hardware (as mentioned earlier). It worked in the Hi-Def NES too.
Next, I socketed a CHR RAM SNROM board (Shingen the Ruler), made a socketed adapter board, tied the extra pins to their respective highs and lows (as specified in the datasheet for Read mode), and popped it in to an NES. It boots but graphics are garbled and it seems to be on different game screens than it should be (sometimes see a non-garbled face that I should only see after completing a mission).
I dumped my franken-cartridge through my Kazzo and the resulting ROM matches the one I got through the EPROM programmer before (maskROM to EPROM adapter). My cart is definitely working for reading the EPROM. Heck, I can try it back to back with my customized cartridge and the Everdrive N8 and it just doesn't work in my cartridge.
I suspected that I damaged the CHR RAM or something so I popped the original Shingen the Ruler ROM back in the socket and it still works perfectly. I'm at a loss!
Anyone know what would cause this? My next step is to burn an EPROM and see if that works but the exact same contents are already there and confirmed readable in the current configuration so I can't see why that would be any different.
The thing is, the proto came on a Toshiba TC571001D EPROM, which uses a maskROM pinout as opposed to the usual EPROM pinout (TC571000D - shares the same datasheet). It's a CHR RAM SNROM game so popping this chip into a SNROM cart should be a pretty straight-forward affair... even more so than most protos.
First, I made an adapter so that I could dump it in my EPROM programmer. This worked and resulted in a dump of the games that worked on emulators and original hardware (as mentioned earlier). It worked in the Hi-Def NES too.
Next, I socketed a CHR RAM SNROM board (Shingen the Ruler), made a socketed adapter board, tied the extra pins to their respective highs and lows (as specified in the datasheet for Read mode), and popped it in to an NES. It boots but graphics are garbled and it seems to be on different game screens than it should be (sometimes see a non-garbled face that I should only see after completing a mission).
I dumped my franken-cartridge through my Kazzo and the resulting ROM matches the one I got through the EPROM programmer before (maskROM to EPROM adapter). My cart is definitely working for reading the EPROM. Heck, I can try it back to back with my customized cartridge and the Everdrive N8 and it just doesn't work in my cartridge.
I suspected that I damaged the CHR RAM or something so I popped the original Shingen the Ruler ROM back in the socket and it still works perfectly. I'm at a loss!
Anyone know what would cause this? My next step is to burn an EPROM and see if that works but the exact same contents are already there and confirmed readable in the current configuration so I can't see why that would be any different.