nesdev.org

Hello world,

I've been looking all over for guides that walk through cartridge building for the NES, (NTSC Toaster is my main model) and I just can't find fully helpful guides that walk through on this stuff. I can find things that give quick rundowns, but not give recommended links or anything, this is all I know about what to do:

(1) Get an EPROM writer and empty EPROM chip (right? If so... Where?)
(2) Take a Donor Cart with the same Mapper as target game
(3) Write ROM to EPROM chip... Desolder original EPROM and do whatever with it.
(4) Solder in EPROM chip where original EPROM was...

Is this correct? Did I miss anything? And where in the interwebz world can I find an affordable EPROM writer? And is it even EPROM or is it actually EEPROM?

Thanks for the time.

Supposedly, the pinout of a NES Cartridge's ROM pins and EPROM pins isn't the same.

Dwedit wrote:Supposedly, the pinout of a NES Cartridge's ROM pins and EPROM pins isn't the same.

Wait... WHAT?!

So then, like... I must be on the wrong track all this time? Ah jeez, how would I go about doing this then and finding these materials?

Dwedit wrote:Supposedly, the pinout of a NES Cartridge's ROM pins and EPROM pins isn't the same.

I keep hearing this, but it works fine for me with my NROM devcart, which is little more than a couple of ZIF sockets pin for pin wired up. So I don't think that's true.

I get my EPROMS from futurlec. Be aware they come from thailand and it takes forever to get from there, but prices are reasonable. You might also try a EEPROM, which supposedly can be electrically erased rather than requiring UV light. I can recomend a Willem programmer based on PCB 5, works well for me but unless you get a third party design it needs a parallell port.

I can also highly recomend the board from retrousb.com, it's really easy to set up and I made a UOROM cart out of it for homebrew. All the parts needed can also be found on futurlec or digikey.

What games are you looking at building carts of? I may be able to help out with supplies stateside (if your in the US that is). I have a lot of this stuff lying around and can make a deal on it.

The pinouts are the same, as long as you stay with ROM sizes below 32kB (27C256). So an NROM board or CNROM board only requires the chips to be swapped. At 128kB for example, NES ROMs are 28-pin while EPROMs are 32-pin.

See the first 3 docs here for probably all the info you'd need to rewire the larger ROMs:
http://nesdev.com/#HardwareCartridges

If you plan on doing much erasing and re-writing of the chips, I'd strongly recommend using FlashROM instead of EPROM. And if you're just gonna burn a chip once, you could get OTP EPROMs which are cheaper and non-erasable.

@R-T-B
My main goal right now is to make a Mother/Earthbound Zero cartridge, And sadly I cannot spare money and I'm 14 and not allowed to give out my address, I do appreciate your offer very much though.

@Memblers
I saved the files to my folders, thanks for pointing me in that direction. So this means that 32kB files are the only amounts possible to simply swap the EPROM? Dang, so I might have more work to do... Earthbound Zero is about 512 kB, PRG is 256 kB and CHR is the other 256 kB.

Also, MMC is some kind of way to say Mapper, correct? Is it just some fancy schmansy word?

Unfortunately, Memblers is right. You'll have to do some rewiring.

Best of luck to you though.

At least Earthbound Zero uses a common mapper/board (TKROM), it should be easy to find a donor cart for it. The rewiring is not such a big deal, and seems to be documented already.

Documented? Where? I must know! I've looked up things like "NES cartridge building" on Google but can never find a guide!

I think I found myself a correct Donor cart from a game called Shadow Gate, according to http://www.nesreproductions.com/mapper4b.html found at NES Reproductions, that list said Shadow Gate was one of the compatible Mapper-i-fied ROMs, so it SHOULD be usable.

Glitchy Furrystuff wrote:Documented? Where?

The link that Memblers gave you, second document in the list (called NES EPROM Conversions). It says what pins to bend and what traces to cut on various boards, including TKROM.

I think I found myself a correct Donor cart from a game called Shadow Gate

Any game listed as TKROM in this list will do.

compatible Mapper-i-fied ROMs

I don't know exactly what you mean by this, but the games in black are games that use TKROM boards, which is the exactly the one Mother needs, so you don't need to do anything crazy like adding batteries, adding RAM or anything complex like that, but since the original ROMs are not pin-compatible with EPROMs, you still have to rewire it as described in that document.

Ah, it appears I got the right game then either way ~

I thought you meant there was a different guide from the one Memblers gave me that had pictures and everything in it, but I can use these text files, thanks to you all, if I need help again I will certainly come here ~

No problem. Just be advised that soldering can sometimes be a tricky business involving a fair amount of burnt fingers (I learned this the hard way. )

R-T-B wrote:Just be advised that soldering can sometimes be a tricky business involving a fair amount of burnt fingers

I have to admit that soldering and desoldering (desoldering mainly) dev carts can be tricky, but burnt fingers is not really one of the problems I have. It only hapenned to me once in several years (I don't do soldering very often though).

My biggest problem with NES boards is that there are always some holes that I can't seem to get all the solder out of, so I always end up with 2 or 3 pins that just won't come out. But if I insist I usually succeed.

I guess I just need to practice more.

standard nintendo board are a pain to unsolder. Konami VRC ones were a charm.