Using BIOS Flash ROMs to make homebrew Famicom cart

[133MHz]

Hi everybody!

I'm in the mood of making my own Famicom (or NES) cart. Well actually removing the PRG and CHR ROMs and replacing them with (E)EPROMs so I can burn games in them. The thing is that I have some 27Cxxx EPROMs but no way to erase and program them. But I also got two Flash ROMs (from old motherboards BIOSes), two 128KB Macronix MX28F1000P (one for the PRG and one for the CHR). These are very easy to program (just hotflash them with the old motherboard and burn them with Uniflash), but will they work in a Fami/NES cart? Or do I have to spend the money on an (E)EPROM programmer and an UV eraser?

[133MHz]

Any ideas? I want to play Antarctic Adventure on a real console

[manuel]

I think most people on Famicom World don't know that much about programming and technics. At least I don't.
You could try http://nesdev.parodius.com/. Maybe you find some useful info there.

[Doc]

Any ideas? I want to play Antarctic Adventure on a real console

Another Antarctic Adventure fan?

[madman]

Unfortunately it's not as simple as that.  You won't be able to just write an EPROM (or whatever) with a ROM and stick it in any cart and have it work.  You'll need a donor cart that uses the same mapper as the ROM you wish to flash.  You'll also need to compare the pinout of the chip you want to use with the pinout of the existing ROM chip on the cart.  Why not just buy a Powerpak and be done w/it?

[133MHz]

Yep, another Antarctic Adventure fan

Antarctic Adventure is mapper zero and so is Elevator Action (which I own). So I want to replace the PRG and CHR ROMs of Elevator Action with my own chips with Antarctic Adventure in them.

Antarctic Adventure (Konami):
mapper 0 (NROM)
PRG: 16KB; CHR: 8KB

Elevator Action (Taito):
mapper 0 (NROM)
PRG: 32KB; CHR: 8KB

I have no problem with getting the pinouts and rewiring the cart (I know the ROMs used non standard pinouts). The thing is that I don't have EPROM erasing/writing equipment, but I do have a pair of Flash ROMs (Macronix MX28F1000P - 128KB each) extracted from some old Pentium motherboards, and I can write those easily with the motherboards, no dangerous and expensive UV lamp and EPROM burning equipment, just a motherboard, the chips and Uniflash.

My question is: By wiring the appropriate data lines/address lines/voltages/etc of the Flash ROMs (each one containing the proper PRG and CHR) onto the cart PCB, will it work? Or do I have to use 27Cxxx series EPROMs?

[133MHz]

About the size, I may repeat the contents over and over again (the 16KB of program and the 8KB of graphics) until I fill the 128KB on both chips.

[madman]

EPROM programming equipment is neither dangerous nor expensive.  You can get a good EPROM programmer that'll handle almost everything you need, including PICs for under $100.  A UV eraser likewise.  Why not just buy a powerpak and be done with it?  It's plenty more convenient.

[133MHz]

The thing costs 135 bucks, it's temporarily unavailable and the shipping would kill my pocket even more. I know it's more convenient, but convenience has a price . And the UV lamp needed to erase those damn chips can be pretty dangerous if you don't shield that thing pretty well while it's working.

[madman]

Shield it?  If you are buying an EPROM eraser that is a bare UV bulb, you've bought it from the wrong place.  Every one I've ever seen is a self contained unit that will shut the light off if the drawer is accidentally opened.  If you hurt yourself with one of those, it's Darwinism at work as you've obviously tried to do something wrong.

So from what you are saying, EPROMs are completely out of the picture as you don't want to spend even $135.  You can't get an EPROM programmer and eraser for that price at all.  Just match up the pinouts on your flash chips with the pinouts on your donor cart and you are set.  You shouldn't need to write the ROM data multiple times, as the upper address ranges will never be accessed and in all likelihood, the address pins used to access those ranges won't even be hooked up (NROM can't address that much data).

That all said--if you just want to do a one-off game like Antartic Adventure, it'd probably be easiest just to find someone with an EPROM programmer who will write the EPROMs for you.  If you plan to frequently write/re-write games you might want to look into mounting the chips w/ZIF sockets too.

[133MHz]

Thanks! Checked http://nesdev.parodius.com and it says Atmel type Flash ROMs work! I thought there may be timing problems or something but it seems I just have to write the PRG and CHR onto each one, wire the corresponding pins onto the NROM board and magic happens! If you have a Socket 7 motherboard lying around it may be the cheapest NES flash cart ever made

[JC]

Sounds like you may have figured it out, but if not, RetroZone offers an NES cart flash card doohickey that allows you to put a whole bunch of games on one cart.

[madman]

JC, did you read the thread?   

[JC]

Scanned it.