Propeller + NES cart?

logan996

Hi, i was curious if there would be any way to partially emulate a NES by reading a NES cart using the propeller to play it on a tv? or if there was any way to compile a NES rom into a rough hydra game version? and if not are there any old game systms that the propeller can use it's cart?

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potatohead

There is a NES emulator in the HYDRA forum. It's a pretty great start. The problem with emulation happens to be RAM. Using real carts is going to consume all the pins on the Prop. Best approach right now, is to get a file filled with the contents of the cart.

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Vaati

Well, there are 72 pins on an NES cart, 56 of which I believe are memory addressing lines. That means that it would require at least 2 props to do anything. Also, as potatohead said, the problem is RAM. I happen to have done some NES development, and I took apart my own NES. I think that one way to truly emulate the NES would be to use the NES PPU (picture processing unit) as a co-processor for the prop and replace the RP2A03 (a 6052-like CPU by motorola) with the prop and load it with the 6052 emulator running the NES boot rom.

I hope this helps answer your question.

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Spork Frog

It could still be done using one Prop: Since the current NES emulator wants ROM data in the Propeller RAM directly anyway, one could use a series of latches or shift registers to retrieve data from the cart byte by byte. Speed may not be great, but I could imagine it would only take on the order of magnitude of seconds at the very most to load a cartridge, and once the game it's loaded, it'd be there until the system is reset. As has been iterated several times, though, RAM is an issue, as cartridges may use up to 48k of ROM (32k 6502 ROM, 16k PPU ROM), assuming they don't use external bank swapping as well.

I can visualize a good Prop setup now for this: A board that contains a Prop, EEPROM, SD card slot, NES cartridge slot, and some external SRAM (addressed however you please.) Plus video and audio ports. This would include code to either dump the roms from cartridge to SD card, or load from SD card directly to the SRAM. What I don't know, however, is if an external SRAM would have enough bandwidth to handle streaming ROM data in real time to the 6502 emulator while maintaining enough speed.

Essentially, it *might* just be doable.