Emulating the cart

tjcarter · Post by **tjcarter** » Mon Dec 08, 2008 1:37 am

I had this total nutjob idea involving a NES and an AVR wired up to the cart port.

Emulating the hardware either on a PC or with a NOAC results in something that isn't quite a NES and doesn't quite play games correctly, but why couldn't you emulate the cartridge itself?

The idea I have in mind, essentially, is to put a game in an AVR's memory and have the AVR serve as a mapper interface for that game (whatever it is), and the NES hardware.

Why?

Well for one thing, you could do the game genie thing. But more than that. You could go as far as you wanted with it, since you'd basically have the AVR as a small microprocessor interfaced to the NES. All you need is to have the AVR present some stub ROM to the NES that tells it how to talk to the AVR, and it could be as simple or as complex a thing as you want.

Now give it flash memory. SD card would do it, and an AVR can be made to read one just fine. The benefits of the superjoy (a cute little menu to pick any game you've got), an emulator (every game you've got, save states, GG support, more advanced development possibilities), and a real NES (the games actually work properly).

More advanced incarnations could even do FDS or other things you can't generally get easily on a real NES. This would be a software update, not a hardware change.

The downsides:

It's cheating. Doing this can make a portable way smaller than otherwise because you don't NEED the 72 or even 60 pin card slot--but it's still cheating! (Doing it inside a regular NES or Famicom cart just because you can would be pretty cool though, for use with the standard toaster.

AVR hacking involved. Most here are hardware hackers, not software. Plus the whole notion of interfacing with the AVR through the NES, while kind of cool, might not be so easy in practice.

Piracy. How do you legitimately get your games on to SD card? I'd be likely to build a reader and program the AVR to do it, but I'm a psycho. Most people are just going to go find Every-NES-ROM-Ever-Made.torrent and shove that on the SD card.

Conflicting goals. GG and hacking features might be cool and all, but they're not really the same goals as most people here, who just wanna make portables and tweak better performance out of their consoles.

Hacking implies typing. I said Apple // monitor, that really would be annoying with a control pad menu. You'd have to have a way to connect a keyboard, and while such exists for the FC, I've never seen one on the NES. I could imagine how to connect one to the cart directly, or build some kind of thing to plug one in to a controller port (and identify that it's a keyboard by it sending back impossible button combinations like up+down at the same time..) It's still more than just a basic cartridge hack at that point, though.

The work. It's an insane amount of work given that there are really some amazing emus out there that do all of this stuff now and work with 99% of the games out there.

Doing it in a cart would almost mandate that you wire up the lockout chip so it works in a standard unmodified NES. It would be easy to do, but the idea of doing it is morally offensive somehow.

Even with the downsides--I did say it was a nutjob idea--I Think It Would Be Cool. Other opinions?

jleemero · Post by **jleemero** » Mon Dec 08, 2008 7:33 am

It's completely possible, yeah.

It'd take a good bit of work, mostly on the side of figuring out how the cart communicates with the system, which more than likely is documented somewhere.

But really, yeah, difficult, but not unbelievably.

I really don't see it as happening though really.

Ben Cebhrem · Post by **Ben Cebhrem** » Mon Dec 08, 2008 9:33 am

http://www.retrousb.com/index.php?productID=133

It's been done, for many years. As far as building your own, I have no clue, but check out http://nesdev.parodius.com/ - it may help some.

jleemero · Post by **jleemero** » Mon Dec 08, 2008 10:21 am

Personally I'd love to see this done for the N64.

I have too many games...

tjcarter · Post by **tjcarter** » Wed Dec 10, 2008 2:48 am

The problem is that trying to do it with CF is the only thing possible because SD would be way too slow at the NES clock speed. Having a faster clock is possible with an extra CPU on the card, and it would be a lot less complexity overall. Probably drop the cost of the cart to sub-$99, and the guts could be actually very, very small.

You could probably make it NOAC compatible more easily that way as well.

Small + NOAC friendly = NESp fun!

jleemero · Post by **jleemero** » Wed Dec 10, 2008 9:23 am

tjcarter wrote: because SD would be way too slow at the NES clock speed.

...
If we can run GAMECUBE backups from SD...

And DS backups from SD...

And GBA backups from SD...

I kind of doubt that 1.79Mhz of NES goodness is gonna be the deal breaker.

Hey, maybe I'm wrong, but, seriously... Wat?

Maybe I'm misinterpreting this or something...
Care to explain?