I have heard that making a NES Flash Cart is such a big problem because of the great number of memory mappers. But if you look at licensed games, three memory mappers stand out, the MMC1 and MMC3/MMC6 and the '161 based mappers (whihc includes no mapper). Consider a cartridge with the following specs:
512KB of PRG-ROM
256KB of CHR-ROM
16KB of CHR-RAM
16KB of W-RAM (with battery)
4KB of V-RAM
With a cart you could handle all the MMC1 and MMC3/MMC6 games that required CHR-RAM or CHR-ROM. You could also handle battery backed games. The CHR-RAM could be used in the '161 mappers that require it (A, B ,C, U*ROMs). The CHR-ROM would be used in the '161 mappers that require it (G, M, R and NROMs).
What couldn't this cart do? Well, it won't be able to handle MMC2, MMC5 or Sunsoft FME-1 games. That is 11 licensed games, most of them Koei strategy games ( and you consider the two versions of Punch-Out separate games.) It can also handle several of Tengen and Camerica's games, and the majority of AVE and Color Dreams/Wisdom Tree/Bunch Games could also be supported without greatly adding to the controller.
Here is how I envision the cartridge to look like. There will be four RAM chips on board. One will be for the PRG, a second for the CHR (whether RAM or ROM) a third will be for the W-RAM (with replaceable battery) and the fourth will be V-RAM for 4-screen mirroring. The games themselves would be downloaded from a USB2 cable or stored on a stick of flash memory that attaches to the cart. The controller chip should stand in between the RAM chips and the cartridge connector to handle those cartridges that have unusual ROM wiring.
If anyone thinks that this is too difficult, I have five words for them: Cuttle Cart 1 and 2.
512KB of PRG-ROM
256KB of CHR-ROM
16KB of CHR-RAM
16KB of W-RAM (with battery)
4KB of V-RAM
With a cart you could handle all the MMC1 and MMC3/MMC6 games that required CHR-RAM or CHR-ROM. You could also handle battery backed games. The CHR-RAM could be used in the '161 mappers that require it (A, B ,C, U*ROMs). The CHR-ROM would be used in the '161 mappers that require it (G, M, R and NROMs).
What couldn't this cart do? Well, it won't be able to handle MMC2, MMC5 or Sunsoft FME-1 games. That is 11 licensed games, most of them Koei strategy games ( and you consider the two versions of Punch-Out separate games.) It can also handle several of Tengen and Camerica's games, and the majority of AVE and Color Dreams/Wisdom Tree/Bunch Games could also be supported without greatly adding to the controller.
Here is how I envision the cartridge to look like. There will be four RAM chips on board. One will be for the PRG, a second for the CHR (whether RAM or ROM) a third will be for the W-RAM (with replaceable battery) and the fourth will be V-RAM for 4-screen mirroring. The games themselves would be downloaded from a USB2 cable or stored on a stick of flash memory that attaches to the cart. The controller chip should stand in between the RAM chips and the cartridge connector to handle those cartridges that have unusual ROM wiring.
If anyone thinks that this is too difficult, I have five words for them: Cuttle Cart 1 and 2.