Using two 28 pin One-roms to replicate a Nintendo NES cartridge

[solidpr0]

Hey Everyone

Very much an amateur/beginniner here. A while back I purchased a fairly rare Japanese Nintendo Famicom Box which is a huge Nintendo Famicom-based machine which holds 15 game cartridges and was deployed to hotels to rent access on overnight stays.

In my case, the machine is nearly operational, but besides the game cartridges, the machine uses an additional game-type cartridge which essentially uses the same format as many early Nintendo NES/Famicom games - a simple cartridge with a security chip and two MBM2764-20 28-pin EPROMS - one for the game data and one for graphics. This is where my machine seems to have an issue - it says the program/game data EPROM is faulty. In the Hotel Famicom Box, this 'game cart' handles the little operating system that provides system checks, manages menus, some graphics and game selection. I can get into all this but no games will boot. There is an error checking screen which says the PRG ROM (which is the game rom on this cartridge) is at fault.

This is a link showing this exact cartridge.

It's been suggested the Onerom would be an untested but credible alternative to burning fresh EPROMS so I thought I would give it ago.

I have also managed to obtain a raw .BIN file which contains the original data from these two ROMs and there is a seperate tool for splitting the data between the 8k graphics ROM and 32k 'game data'. Now we get to how I apply this data to the two OneROMS - I don't know!

The only lead I have is from the chap who supplied the original data and he said "my guess is configure the CHR ROM to be 2764 and the PRG ROM to be 27256, but it's possible you'll need other settings. If that doesn't work try the CHR ROM as a 27256 as well, duplicating the image x 4 to fill it. - the originals were actually RP23256E and RP2364E which could require slightly different settings."

The OneROM notes says my 28 pins models are correct "28 pin Emulates 23128, 23256, 23512 and 231024 mask programmed ROMs and 2764, 27128, 27256 and 27512 EPROMs."

Can anyone give me any pointers as to my best chance of getting the data onto the OneROMS and behaving like the original chips in the machine? I suspect I've already missed something in forcing the OneROM to 'act' like the chips I'm replicating?

Thanks all! I will document all what I do and help make this public knowledge successful or not! I keep a rough blog of all the machines I try to fix and restore and I'm continually updating this page on getting this machine working!

Alex

[piersfinlayson]

That sounds like it was me. What have you done so far? If you can upload the .bin file I can take a look and figure out how to split it up and program it. If you've rather DM me, do that.

[solidpr0]

Hey Attached I've put the raw file I was sent I think used by emulators, which is a single .nes file. And then I used 'FamiROM' which is a freeware tool that splits the .nes file into 2 ROM files: - PRG (game ROM) 27C256 (32Kb) - CHR (graphics) 2764 (8Kb) So I think these are what you'd actually burn to an EPROM, with maybe theCHR one on repeat 4 times. Any help you can give would be great - I'm on a steep learning curve. I think the 'FamiROM' program does the splitting for burning to EPROMS as it should. I think all I need to do is setup the OneROM to emulate the pinout of the two 28pin EPROMS on the cart and then 'burn' the data to each OneROM to 'have' the original data.... [NES ROM and Split Files for EPROMs.zip](https://github.com/user-attachments/files/32413969/NES.ROM.and.Split.Files.for.EPROMs.zip)

[piersfinlayson]

That zip file contains the two files you need. One for the PRG ROM, which needs to be programmed as 27256, the other for the char ROM, programmed as a 2764.

Start here for how to program One ROM: https://youtu.be/Zoits2OSE8g?si=KIwpy1JK27_IXUsU

The whole getting started playlist might be of interest: https://www.youtube.com/playlist?list=PLXs34HaWLi11VhlJEYf_Ff59cxOqqnIkP

[solidpr0]

Thank you, I watched the youtube stuff which all made it extremely simple. I wrote the PRG rom file as a 27256 and tested it on the Famicom Box and it worked! So, essentually another system helped with the OneROM! I'm going to share my outcome on my blog with the OneROM files but is there anything else I can help test or do whilst I have this box up and running with socketed EPROM slots?

[piersfinlayson]

Thank you, I watched the youtube stuff which all made it extremely simple. I wrote the PRG rom file as a 27256 and tested it on the Famicom Box and it worked! So, essentually another system helped with the OneROM! I'm going to share my outcome on my blog with the OneROM files but is there anything else I can help test or do whilst I have this box up and running with socketed EPROM slots?

Glad to hear it! A photo and note would be good over at #31 if you have time.

[solidpr0]

I've added to that thread. Thanks for all your help!