nesdev.org

I think you should consider DRAM instead of SRAM; SRAM at that density not only is way expensive but is IMO completely wasted on a SNES device.

I doubt he wants the added expense / complexity of using an extended PCB and capturing the SNES' DRAM refresh signal, to refresh his own DRAM chips.

<= 4MB SRAM can't possibly be that expensive still.

Who needs the SNES' refresh signal? You can just base your timing off /ROMSEL and an oscillator like a copier. Some copiers don't even have hidden refresh, they rely on just /RAS from addressing.

BTW, 4MB of true SRAM (2x TSOP) is at least $30 and very hard to source... compare that to $4-5 for 8MB of flash (1x TSOP) for the same application. If RAM is needed without worrying about refresh, you'd be better off getting PSRAM (<$8) for 8MB if you can solder FBGA.

I second kyuusaku's suggestion of PSRAM (pseudo-static RAM). It's in the Nintendo DS, and it's in GBA copiers such as M3. It's a DRAM chip with a built-in controller that makes it look like SRAM to the surrounding circuit. But you might need level shifters to get any modern RAM to work with the 5.0 V bus of classic game consoles.

8MB of PSRAM would be quite nice. Then you could support memory mappings for games using large amounts of ROM, such as for that Star Ocean hacks that is 96mbits.

I'd never really heard anything about PSRAM before, but I did know about how DRAM is cheaper than SRAM but requires refreshing so it doesn't decay. PSRAM sounds very nice.

I have one of those GBA M3 Mini SD models, and they are very cool as they are the size of a GBA cartridge and no more.

I'd prefer a modern copier for the SNES. Something that would be hands down better than any existing flash cart or copier for the SNES.

I'm thinking of something like a Game Doctor SF7 with a CF slot instead of a floppy, a USB port instead of a parallel port, and a cart slot that can be used to dump ROMs, upload saves, and pass-through any SNES game or cart (e.g. Super Gameboy).

While your at the wish list, it should have a FPGA or something and by able to emulate every coprocessor there is.I mean while we are dreaming we might as well aim as high as we can. :p

I'd be happy with just a flash cart that loads off CF similar to the devices that exist for GBA. I don't really need to dump any SNES carts and if I did I already have a copier.

PSRAM looks like the ideal solution... but the ones I found are 1.8v and tiny BGA. no way. They had a 3.3v BGA one, but its 'obsolete'

SDRAM is no good, there is way too much latency. You have to send a bunch of commands and wait a lot of cycles.

So SRAM looks like the choice. The cart doesn't need a battery, so that frees up a lot of space! And the 4 bus buffer chips can be replaced by a larger CPLD

Emulating custom chips has very limited use... but adds something new, and lets you play the most interesting games. But it also looks really difficult

How about reverse engineering the SNES CIC? That is if its a standard chip, not a custom one like the tengen. Tracing out the entire circuit does not look like fun.

MottZilla wrote:While your at the wish list, it should have a FPGA or something and by able to emulate every coprocessor there is.I mean while we are dreaming we might as well aim as high as we can. :p

If FPGA are in the picture, why not emulate the SNES along with the coprocessors?

cybertron wrote:PSRAM looks like the ideal solution... but the ones I found are 1.8v and tiny BGA. no way. They had a 3.3v BGA one, but its 'obsolete'

SDRAM is no good, there is way too much latency. You have to send a bunch of commands and wait a lot of cycles.

So SRAM looks like the choice. The cart doesn't need a battery, so that frees up a lot of space! And the 4 bus buffer chips can be replaced by a larger CPLD

Emulating custom chips has very limited use... but adds something new, and lets you play the most interesting games. But it also looks really difficult

How about reverse engineering the SNES CIC? That is if its a standard chip, not a custom one like the tengen. Tracing out the entire circuit does not look like fun.

I was kidding about the custom chips.

If you can create a SNES cartridge that loads roms off CF or SD card, I wouldn't care if its SRAM or DRAM or PSRAM. So long as it's reasonably affordable and works well, I'd be quite happy.

I think real cartridges are the only source for lockout chips. It is possible to use another cartridge as a piggy back but thats rather nasty to do. It'd be better to just find some shitty sports game and sacrifice it to the gods.

MottZilla wrote:It'd be better to just find some shitty sports game and sacrifice it to the gods.

Now that's a butchering I CAN agree with. We've got enough crappy old sports games rotting in pawn shops here to fill a warehouse or two.

Well this video game store in Toronto has a box of crappy sports game for $1 each, so I will pick up a whole pile for the initial run.

Sports games are great, most of them have Save RAM inside them, so they are perfect for homebrew. NFL Quarterback Club 96 is interesting, its an actual 4MB LOROM game! I didn't know that was possible.

I just pop the CIC chip off with a heat gun, it melts all the solder at once.

I am making 20 units of the flash cart. if more sell I can order a ton more boards from China

kyuusaku wrote:If FPGA are in the picture, why not emulate the SNES along with the coprocessors?

That would have to wait for 2011, when key Super NES patents (presumably owned by Nintendo, Ricoh, and Sony) expire. Famiclones just became legal[1] throughout the developed world a couple years ago, when Nintendo's patents on the NES expired.


[1] Except when bundled with a pirate multicart.

Well in that case they might as well get their R&D done now so they'll be ready to produce in a few years.

If the console is implemented using reverse engineered documentation and isn't enclosed in a similar case, why do the patents have to expire?

So I went to the video game store, but they only had four $1 games left

One of them is Mario Paint. Any objections to taking this one apart?


On the back of the cart is a list of patents!

http://www.google.com/patents?id=81EWAA ... dq=4799635 (CIC chip for the NES)

http://www.google.com/patents?id=JMwDAA ... dq=4984193 (Memory Cartridge, again for the NES)

http://www.google.com/patents?id=6G43AA ... dq=4801489 (PCB layout to prevent interference. I think this is that bloody copper layer on the bottom of the SNES mobo! Makes it hard to access bottom traces)

http://www.google.com/patents?id=h8kpAA ... dq=5070479 (External memory with authentication processor. Looks like its still for the NES, but issued in 1991)

Pretty interesting