Thank you for you fast response! I don't know right now of any ROM that needs SRAM save and ROM size is 4 MB's*. My intention was to make a cart with swappable eproms, that supports the ones with save.
So, if I want to use a donor cartridge with 2 MB's with save, and put a ROM with 4 MB's that doesn't needs save, I should short in some way the SRAM's pins to avoid any problem?
Woah, those pcb's seem very cool, I wish I knew enough electronics to make one with save.Originally Posted by Jazzmarazz
3. I make new PCB's, yes. I have designed several different boards based on different configurations of RAM/ROM. Each one of them was designed with the idea that I can only use "new" and "commercially available" components. See:
Spoiler warning:
The first board is my design with 2MB's ROM and 256KBs battery backed SRAM. With the use of a jumper located in the top left, the user can change the mapping of the board to just 1MB ROm and no SRAM.
The second board is simply a 1MB ROM with no SRAM. The special thing about this board is that it uses two 8-bit ROM ICs rather than one 16-bit ROM IC.
Both of these boards are reprogrammable via the cart edge.
*I just remembered when writting this post, that Sonic & Knuckles + Sonic the Hedgehog 3 is 4 MB's and uses save, but I don't know how it works, since is actually, two games together, I guess it uses battey backed SRAM in one of the two cartridges. So maybe is not possible to save with that kind of ROM.
Thank you so much again for your clarifications!
