Need help building devcart...

This is an archive of a topic from NESdev BBS, taken in mid-October 2019 before a server upgrade.
View original topic
Need help building devcart...
by on (#27587)
Hello,
I'm new to these forums but I've known of this website for it's huge amount of info on the NES and SNES.
I want to make my own Final Fantasy 3 cart, but also have it as a Mapper #4 w/ SRAM dev cart.
I own Super Mario Brothers 2 (the one with 72 pins), an old crappy pirate cart (to take the SRAM from), Kirby's Adventure (I was thinking of using this instead of SMB2, but then I found out that it was rare so...), a network card with a 28-pin DIP socket that I can flash EEPROMs with if I use UniFlash.
I also own a soldering iron, and some desoldering wick.
Now, if I was to desolder the PRG chip on the SMB2 cart and replace with a DIP 28-pin socket and put a chip in there that has FF3E on it, and if I desoldered the CHR chip and put SRAM in it's place, would this work?
Thanx!

by on (#27612)
I cant really help because I've never made FF3. Its probably the hardest or second hardest cart to make (I've also never made Destiny of an Emperor 2 which I believe is even harder to make)

Here are some things to try to figure out though:

1) Final Fantasy 3 is TNROM, so you need to figure out how to find or convert an existing cart to be TNROM. Super Mario 2 is TSROM.

2) Final Fantasy 3's PRG is 512 KB which means you need a 4 Mb EPROM (eproms are sized in bits not bytes). You mentioned a 28 pin chip. I dont think the chip you need is 28 pins (more likely 32 pins)

3) Final Fantasy requires battery backed RAM. That means that even if you used SMB2 you still need to properly add a battery.

You may be able to find at least some information here:
http://nintendoallstars.w.interia.pl/ro ... m2cram.htm
I dont know how good the information is because I've never tried it.

Al

by on (#27619)
You'll want to either add a battery to SMB2 OR replace the CHR-RAM of Kirby's Adventure by a CHRROM chip. Both are moderately hard to do I guess, but I haven't done any of them both yet. I guess some people arround did all both of those and ended up with a working cart, so that's do-able.
Adding a battery proprely is tricky, as you'll need a couple of diodes or resistors, and have it fill in a board that doesn't technically have the room for it. I already explained the battery backup circuit one million times arround.
Replace CHRROM by CHRRAM on a TKROM board is hard because you have to add a non-existant pin on the connector, but this should be doable if you are carefull.

It's one of the hardest cart to make unless you have FF3j as a donor (Destiny of an Emperor is also TNROM so they are ex-echo on the totem pole).
I guess make a VRC cart or something should be harder, as there is no cart with the good mapper at all arround, so you'll have to either mapper hack the game, or implement the chip as you can.

by on (#27624)
Bregalad wrote:
...replace the CHR-RAM of Kirby's Adventure by a CHRROM chip.

What? Kirby is TKROM, it has CHR-ROM.

Quote:
Replace CHRROM by CHRRAM on a TKROM board is hard

Now you are saying the opposite of the above! =)

What is TNROM, exacly? I never heard of it.

by on (#27627)
TNROM is an MMC3B board with possible PRGROM sizes 128, 256, or 512KB. It uses CHRRAM and PRGRAM that can be battery-backed. You can see here. Final Fantasy III and Destiny of an Emperor II are the only two games to use TNROM. Only Famicom HVC-TNROM boards exist; NES-TNROM boards were never made.

by on (#27631)
I for one never disassemble any game for parts for various reasons. I always buy them.

by on (#27632)
you cant buy fan translated game cartriges

by on (#27635)
No but the parts for it you can.

by on (#27639)
Where can one buy "the parts for" a game that uses a Nintendo ASIC mapper, other than by buying a PowerPak? And does this include the CIClone?

by on (#27641)
Those? I don't know but Eproms and stuff like that you can.

by on (#27643)
(blatent advertising mode on)
www.retrousb.com also has parts for building carts in the NES Parts section. There's a new pcb for NROM/U*ROM/CNROM/A*ROM, a new pcb for MMC1, new cart plastics, and the Ciclones. None of the boards need rewiring to use the supported EPROM/Flash chips. There is no MMC3 (too big for a cheap chip) so you still need to hack a donor board for FF3.

by on (#27645)
Considering the trouble, I don't understand why anyone wouldn't just use one of bunnyboy's incredibly cheap PCBs. Desoldering, solder bridges, etc. are just too time-consuming to deal with, and you're destroying old hardware in the process.

by on (#27646)
blargg wrote:
Considering the trouble, I don't understand why anyone wouldn't just use one of bunnyboy's incredibly cheap PCBs.

For raster effects where spinning on sprite 0 isn't enough.

by on (#27647)
blargg wrote:
Considering the trouble, I don't understand why anyone wouldn't just use one of bunnyboy's incredibly cheap PCBs. Desoldering, solder bridges, etc. are just too time-consuming to deal with, and you're destroying old hardware in the process.


I am sure bunnyboys version of the mappers are pretty close but still not nessacerally identical to Nintendo's one

also in most cases it as simple as desoldering the mask ROMs and adding a few wires. Only boards like this one is hard and BB dose not have an answer for it

by on (#27648)
Agreed, and it's much simpler and cheaper to buy a cart in a garage sale than import a brand new cart from Canada. Of course when it comes to rare carts or japanese carts, that's another story. And most TKROM games are rare, the only really common TSROM one is SMB3 (and possibly SMB2), but they still lack the additional CHRRAM pin necessary for TxROM->TNROM conversion.

by on (#27693)
hmm...this shouldn't be impossible...
what does this whole TNROM thing mean anyways? is it just a type of cart?
is it impossible to turn any of these games into FF3j?
Kirby, SMB2, SMB3, Metroid, or StarTropics? I have these games and I'm willing to give these up if I can turn it into a FF3j English cart...
Also, I have a few Famicom carts lying around (3 are multicarts and 1 is Side Pocket).
Are any of these of use?
Thanx! :D
EDIT: One more question.
Is it not possible to turn a TSROM board into a TNROM board? A few switching of pins should work shouldn't it?

by on (#27694)
Vorde wrote:
hmm...this shouldn't be impossible...
what does this whole TNROM thing mean anyways? is it just a type of cart?

Yes, named after the name of the circuit board inside the cartridge.

Quote:
is it impossible to turn any of these games into FF3j?
Kirby, SMB2, SMB3, Metroid, or StarTropics? I have these games and I'm willing to give these up if I can turn it into a FF3j English cart...

There are people who will buy a few of those off you and give you enough money for the FF3 remake for Nintendo DS.

by on (#27699)
it is possiple but I am not 100% on the actual wireing

why doseint someone give him the wireing information he wants?

by on (#27710)
The info already exists in a doccument by drk414 available on the NesDev main page. (it explain how to change TKROM to TNROM)
Change TSROM to TNROM should be possible, but a lot trickier due to the lack of on-board battery. I guess you should apply the same as TKROM to TNROM, and after that you should either replace the SRAM chip by a Dallas self-battery-backed SRAM, which would save a lot of trouble, but they are expensive and they will probably never fit a NES cart or even a frontloader NES console because the chips looks high. Alternatively, you can find a way to add the 2 diodes, 2 resistors and the battery needed for the backup circuit without a board for them by wiring them on the go and find a way to make it fit the cartridge.

by on (#27740)
so basically if i'm willing to go through the trouble turning a tsrom board into a tnrom board, it should work right?