nes recreation. I need help.

[bluej774]

I'm tired of these "mostly compatible" non-DIY NOACs. I'd like to recreate an NES. I'm a bit of a perfectionist and I want total compatibility without having to tear apart an existing NES. I believe it is possible. There are some schematics available here for the original NES. The expansion slot and the lockout chip can be removed from the design. SRAM would be easy to get and use. However, the problem comes in with finding modern equivalents to the RP2A03 chip and the RP2C02G.

I need to know if modern equivalents exist and if any code would need to be written to those chips. I don't believe they need special code because if it did, someone would have dumped the code from NES chips by now. I know there are plenty of 8-bit microprocessors around, so one of them must work for this application.

I'd appreciate any help or advice concerning identification of suitable replacement components.

[marshallh]

It is possible. You'll just have to learn a LOT.

The NES is well documented, you can recreate the hardware in a FPGA (google that and see if you can understand it.)

It's not something you can do overnight, for sure. And since the CPU and PPU were custom-made for Nintendo, there are no drop-in replacements.

Suggestion 2: Lay out a PCB and transplant the important components into it.

[bluej774]

I have reservations about taking apart NES systems. I believe they should be restored and kept working. Not ripped apart. I fear the day when most of the NES boxes are gone.

I guess I have two options, then, if reconstructing the NES is far too complex to be rewarding.

1) I can use some NOAC. Are there any that replicate the NES perfectly? If not, what chip is the closest I can come? Is it possible to order just the NOAC without having to buy a clone and crack it open? It would be so much cheaper.

2) Recreate the NES on a FPGA. I'm totally willing to give it a shot as it seems it's been done before. I will need help, but if I can do it I will publish my source freely.

Any advice for NOAC or using a FPGA? Also, although I already have the schematics for the NES, what other info will I need for the FPGA solution?

[gannon]

PIC would be impossible. FPGA is possible (and has been done), but AFAIK you'd need level converters for the cart. Read up on hardware docs, RE the chips by decapping them, and read up on better emulator's source code.

[bluej774]

Why would PIC be impossible?

Assuming I were to go about using a FPGA setup, how much power would my FPGA need? I want to keep the parts cheap. Would 2910 logic blocks, 2910 registers, and 65 I/O be suitable? I don't see why not considering how limited original NES resources are.

[marshallh]

No.

[bluej774]

Well, can someone offer me some links for more information? I don't know what type of FPGA I need.

Also, any particular reason why a PIC like PIC18F4550 wouldn't do the job?

[gannon]

You'd be lucky to get a color composite NTSC image out of a PIC with it's processing power, let alone any CPU emulation. You wouldn't even be able to get good NES emulation out of a 20-48MHz PC.

[bluej774]

Not that I'm married to the idea of using PICs, but couldn't I pull a Nintendo and delegate the work between 2 8-bit PICs? I mean, basically reinvent the code on their own chips?

What kind of FPGA would I need bare-minimum to be an NES?

Also, what about using the Parallax Propeller chip? Could that be used to recreate the NES?

[marshallh]

Here's a good idea of what you need to recreate the NES in an FPGA.

And please don't bug Kevin Horton.

http://tripoint.org/kevtris/Projects/co ... index.html

Using PICs to replace the cpu and ppu wouldn't work either because they have different pinouts/instruction sets and aren't fast enough to emulate their own chip fast enough.

[bluej774]

I've seen Kevin Horton's project. It's a great inspiration. At the same time, I don't like his design. The FPGA chip he uses is far too expense for what my aim is and I believe it is overkill.

Here is what I'm planning for the time being. Parallax Propeller acts as the processor. An EEPROM chip will hold the emulator code. An SRAM chip will provide enough RAM for NES emulation. A couple of translation chips will be needed for the conversion of data from 5V to 3.3V. That's pretty much it besides small components like a crystal oscillator and the like. Doesn't that sound plenty capable of being an NES?

[Skyone]

Here is what I'm planning for the time being. Parallax Propeller acts as the processor. An EEPROM chip will hold the emulator code. An SRAM chip will provide enough RAM for NES emulation. A couple of translation chips will be needed for the conversion of data from 5V to 3.3V. That's pretty much it besides small components like a crystal oscillator and the like. Doesn't that sound plenty capable of being an NES?

Ya, I was just about to suggest the Propeller. Also, I think there's some support to run the Propeller at 5v, check the Parallax forums for that, though. I think it's powerful enough to emulate the NES and more, so I'd give it a shot. What are your plans for storing the ROMs, etc? I know the Propeller is great with I2C/interfacing with SD cards, so that's a nice route.

[bluej774]

Wow. If I can run the propeller at 5V, I may be able to skip the level translation ICs. Thanks for confirming what I thought.

I'm actually not looking at playing with roms. I'm looking at playing with real cartridges.

[Skyone]

I'm actually not looking at playing with roms. I'm looking at playing with real cartridges.

Ah, gotcha. Might want to think of integrating SD/ROM support, though.

http://forums.parallax.com/forums/defau ... 5&m=124837

Ya, it was a sticky.

EDIT: http://forums.parallax.com/forums/attach.aspx?a=12294 - shows an easier resistor solution to interface between I/O ports.

[ATOMICMAN]

I'm actually not looking at playing with roms. I'm looking at playing with real cartridges.

sd would be cool along with a cart slot to try your own custom hacks or play roms as a backup.