There's a nice new devcart page over at nesworld.parodius.com
Currently it features rewiring info for SLROM and UNROM.
http://nesworld.parodius.com/devcart.htm

ive done one sucessful rewire of an unrom cart but the second attempt came up with a glitch, i tried to put ghosts and goblins on a nes unrom cart (robowarrior i think it was) anyway, the cart starts up but the graphics are corrupted, what would cause this? the game plays but the graphics are all jumbled, could it be the ram chip on the cart or a faulty eprom chip, that i used to program ghost and goblins onto? i also tried to put galaga onto a hotwired nrom cart and that had the same problem/sorta, the game plays fine but the black spots of space in the background are taken up by 0's instead, the stars still move in the backgroundand the ship and mosters are visable if they move, else they become 0's in the screen of 0's. ive wired the cart correctly on both carts, but there is corrupted graphics, are both carts suffering faulty eproms? could static from myself have caused damage to the eproms? the pc roms i took them from work under nesticle, and i used tnines to split them to headers/footers/chr/prg could it be tnines? i split it a few times to make sure but it came out the same, and waiting 20 odd mins at a time to erase the eprom and then prog again and still it came up with errors, i cleaned all the contacts on the board, the only difference in the two unrom carts is i used a socket to be able to remove the eprom if things didnt go right, could the socket be the problem?

to many possiblities hmmm

help!

If the game runs, you can be pretty sure the PRG EPROM is OK.

With the UNROM cart, I'd guess either the CHR-RAM went bad or maybe the board is wired differently than expected? (I doubt it). Maybe you could put the original game on the EPROM to verify the latter. If you'd want, I could slap together a little CHR-RAM itegrity tester program.

For that NROM cart, I'd guess the CHR-ROM might have a wire or 2 in the wrong place. EPROM writers (the one I've seen anyways), have read/verify options. To check if EPROM is OK you could read it to a file and in DOS type "fc /b file1 file2" to compare the files.

i found the problem! it was in the v-mirror h-mirror solder joints, i swapped them on both carts and presto, i now have a working version of galaga, and ghost 'n' goblins!!!! yay!!!

me a stoopid head, i only thought of it today while i was at work, maybe the original games on these carts was the opposite mirror, and it worked just like that!

my next cart is gyruss on a cnrom cart.

i found the easiest way to make a nrom dev cart is use a third party cart, the pinouts are the same because 3party used eproms to begin with hahahaha, i just cant believe my own luck!
thanks for your help!

once ive done gyruss, the world is my oyster, sorta :P

i have a friend who's father is just about to start up a pcb business, so im hoping with some nudging that i might be able to design a pcb dev cart that will fit into a standard cart with zif sockets (hopefully) im just gunna have to take in a few stripped carts to do so, i may be able with some help from their software be able to put all major memory mappers on it and be able to switch between (maybe) lots of maybe's we shall see...
its all in the air at the moment but it is possible........

D'oh! So it was the mirroring. The obvious solutions are easily overlooked.

About the PCB thing, that would be cool. All you really need is some cart cases and lockout chips (both of which can be harvested from surplus SMB/DH carts). The ZIF sockets will pose a problem, unless there are special ones that are small enough to fit into the case.

I was thinking about designing one, but I don't really know enough to be able to. I've got one design that seems simple, and one that's absolutely obscene.

The simple one would have CHR-RAM, and good PRG switching ability (up to 4MB for at least $8000-$BFFF). Yes, 4 megabytes. =D
That'd be basically a supercharged UNROM.

The other one would pretty much be a computer in a cartridge. It would have a CPU (prolly a 65c02), small BIOS rom, and it's main RAM (dual-port) would be the cartridge's CHR-RAM. A kind of graphics-accelerator. Of course, I'd want it to have lots of other neat and useful stuff and it would probably be a miracle if it could fit inside a cartridge case.
This is similar to Color Dreams' vaporware Hellraiser cartridge.

i had another idea, ive spoken to my engineer friend and he suggested having a BIG flash rom in the cart soldered in (unrom cart for example) with a microchannel socket situated on the cart somewhere which directly links to the flash which can be directly linked to pc to flash and reprogram with what ever you like if not more than one program and a trigger to switch between games and i had another idea, in that do you think it would be possible to make a super gameboy equivalent for the nes except that its full screen and plays through the nes- sort of like the hellraiser cart except the processor on board could be a z80 with direct link to a compatible socket on the cart to play gameboy games... its an idea and my engineer friend has worked with 6502's and z80's quite alot so he (being the brains) might make something out of it, im gunna give him my old frontloader nes and my snes and n64, cause he is intrigued by them, i might nudge him into making a copy-n64 (maybe), i also thought of that myself.... make a ram/flash cart and plug a cable into the expansion port in the bottom that can download roms from the net onto it or something like that anyway, its only fantasy, but wouldnt it be grouse!!!!

I don't know much about flash rom, but it seems like it would work. Wouldn't the program need to be copied into RAM or something? Or can it run directly from the flash rom?

The super gameboy had all the gameboy guts in the cartridge, it only used the SNES for the controller and border stuff. I think SNES has a video-in on the connector to get the gameboy screen, the NES doesn't have anything like that available. But maybe there is another way.

I've read about some N64 copiers on the internet, there's a wide variety of different ones. Most are stand-alone systems that load from ZIP disks, and I've seen a cheaper one that was just a cartridge with a cable to hook to a PC.

flashrom from what i have invested some time into now will and do work on cartridges, i currently have commando on a nes unrom cart with a flash am29f010 as the prg rom, the cart is that roomy i could put a small pcb with 6 or so flashroms on it and by dip switch i could enable and disable all the various flashroms, and enable different games. they run on 5 volts to run them and 12 volts to program them, the life of a flashrom is shorter than an eprom, that is true and you can only flash them 10,000 times which is more than enough.

i found that my friend in the pcb business prior to this new business created mini rack modems for a large telecommunications business here in australia, and has zquillions of these modems floating around, they have a microchannel input that attaches to the pc via a serial port and has a z80 processor onboard to process the incoming/outgoing data and has a 1megabit flash onboard which is reprogramable via pc software. the funny thing is this modem easily fits inside a nes cart and with a little mod could be used to program a flash or two on a nes cart, my friend says anyway but thats in the air, he is a very busy person so ill try this week to see if he has any time to see if he could look into this for me.

i have another query about carts and mirroring. does anyone know how to flip the mirroring on a cart which is third party cnrom equivalent but only has one type of mirroring on it, i dont know which one it is (it is unmarked) my galaga cart which i used a third party cart for was straight forward and just needed solder to be sucked off it and replaced on another connection above it, but this cart doesnt seem to have that other connection attached to anything.

its something like a nina-3 cart or something, ive put cybernoid into this cart and the graphics are a little glitched on the opening screens and with in the game occassionally. but mainly the opening screen is glitched. ive tried this game in a socketed cnrom cart with h-mirror enabled and it had the same glitches and changed it to v-mirror which fixed them without any mirror it becomes almost unplayable, the graphics become so corrupted.

the third party cart i have cybernoid in was made by home entertainment suppliers (australia) 1991 printed on it and the code ntd-2b

and has a 74ls161an chip on it too and has room for 3 other chips on it, obviously 1 cart design for many different games to be programmed onto it but as i said i guess its set to h-mirror or no mirror are the two options, what would i need to do to make it v-mirror enabled? what pins do i jumper?