Quick NES homebrew devcart query

[sack-c0s]

I'm currently attempting to wire an old mario bros cart up to use as a devcart for hardware tests (using an FPGA with RAM and flash memory instead of eproms).

 

So far as I can see if I supply a ROM image for the PRG ROM the program itself can copy tile data to the PPU and you can live without a CHR ROM. what I want to know is if this assumption is correct and are there any alterations I would need to make to the cartridge to make this happen?

 

so far the only alterations I have made are to unsolder the ROMs and I'm starting to solder a cable in place of the PRG ROM so the FPGA board can supply the data in its place from its own ROM/RAM (and potentially act as a mapper in the process.

 

Thanks

Edited April 4, 2006 by sack-c0s

[Bruce Tomlin]

what I want to know is if this assumption is correct and are there any alterations I would need to make to the cartridge to make this happen?

The cartridge has to have extra VRAM first. And of course you will have to change the game to actually download the CHR data.