In an effort to improve my dev environment, I'm interested in making some basic dev carts. As I've got some interest in electronics design, I'd like to make my own from scratch rather than use a donor cart or a Retrozone PCB.
As a first step, I'm working on a basic NROM schematic. It's designed for two DIP-28 and should be able to handle CHR RAM or ROM. Jumper 1 controls mirroring. Jumpers 2 and 3 are PGR and CHR write enable, respectively. (Which you want to disable if you're using writable memories as though they are read-only.)
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I think this basic design is done, but I'd like someone to proof it for me. Is there anything I forgot? Anything I've screwed up?
I haven't figured out how I'm gonna program this yet, but an EEPROM burner and sockets would be one option. Eventually I'd like to be able to program the chips while still in the cart. Any suggestions?
Once I'm satisfied with this design, I want to add WRAM and experiment with some simple mapper designs. I'm thinking of implementing the WRAM with an FRAM, so I can have the equivalent of battery backing, without batteries. FRAM would also make a pretty nice "ROM" for a dev cart.
As a first step, I'm working on a basic NROM schematic. It's designed for two DIP-28 and should be able to handle CHR RAM or ROM. Jumper 1 controls mirroring. Jumpers 2 and 3 are PGR and CHR write enable, respectively. (Which you want to disable if you're using writable memories as though they are read-only.)
Full Size
I think this basic design is done, but I'd like someone to proof it for me. Is there anything I forgot? Anything I've screwed up?
I haven't figured out how I'm gonna program this yet, but an EEPROM burner and sockets would be one option. Eventually I'd like to be able to program the chips while still in the cart. Any suggestions?
Once I'm satisfied with this design, I want to add WRAM and experiment with some simple mapper designs. I'm thinking of implementing the WRAM with an FRAM, so I can have the equivalent of battery backing, without batteries. FRAM would also make a pretty nice "ROM" for a dev cart.