Edit: UQROM is just what I'm calling UxROM with PRG-RAM.
Hi all! As I have mentioned before I know just enough about hardware to be dangerous
I am trying to create a UxROM cart that can support battery-backed WRAM and 4MB of PRG-ROM. Realistically I would never have need of such a behemoth cart, but I figured it would be best to design it that way. When it comes time to build I would probably go with a 256KB board.
Anyhoo... after lots of reading on the wiki and the forums I've come up with this working design. It's basically the UxROM reference design with an 8-bit latch register and quad OR gates, plus the PRG-RAM reference circuit mashed together. I have also added an extra OR gate to prevent writes to WRAM from setting the bank select register, and I have added an PRG R/W inverter to prevent bus conflicts with PRG-ROM.
I am really just working on a whim and a prayer here. Can someone vet this design for me?
I might also want to add some sort of logic to swap between horizontal and vertical name table mirroring. I'll have to think about that though.
Also, I've got three 2-input OR gates not in use in this design. Any thoughts on how to make use of them?
Fairly large image
Thanks!
Hi all! As I have mentioned before I know just enough about hardware to be dangerous
I am trying to create a UxROM cart that can support battery-backed WRAM and 4MB of PRG-ROM. Realistically I would never have need of such a behemoth cart, but I figured it would be best to design it that way. When it comes time to build I would probably go with a 256KB board.
Anyhoo... after lots of reading on the wiki and the forums I've come up with this working design. It's basically the UxROM reference design with an 8-bit latch register and quad OR gates, plus the PRG-RAM reference circuit mashed together. I have also added an extra OR gate to prevent writes to WRAM from setting the bank select register, and I have added an PRG R/W inverter to prevent bus conflicts with PRG-ROM.
I am really just working on a whim and a prayer here. Can someone vet this design for me?
I might also want to add some sort of logic to swap between horizontal and vertical name table mirroring. I'll have to think about that though.
Also, I've got three 2-input OR gates not in use in this design. Any thoughts on how to make use of them?
Fairly large image
Thanks!