Burned Mapper 0 game, getting gray screen

Burned Mapper 0 game, getting gray screen
by Computolio on 2006-01-24 (#8522)

So as an extremely late celebration of Bokosuka Wars Awareness Month, I decided to use my new EPROM burner to put the game on a real NES cart. I found a Mapper 0 (NROM board)-based game (Baseball), and swapped out the mask ROMs for EPROMS I had burned.

I used uCON64 to split the .NES ROM into .PRG and .CHR files, and then burned one onto a 27C256 and the other onto a 27C64 EPROM.

So I put the whole mess back together and am getting a gray screen. At this point I think I picked out the wrong donor board, as it's an NROM-128 and apparently games with 32k PRG should use an NROM-256. Any way I can fix this without having to start over?

by Quietust on 2006-01-24 (#8523)

Yes, that would indeed be a problem - NES-NROM-128 is only designed to handle 16KB of PRG ROM, and you're trying to give it 32KB.

CPU A14 would normally go to pin #27 on the ROM - try cutting the current trace and then running a wire from the cart edge (you'll probably need to shave off the solder mask at the end of the pad) to pin 27 on the PRG ROM.

by WedNESday on 2006-01-24 (#8527)

Now is that link the funniest thing that you've read or what?

by Computolio on 2006-01-24 (#8546)

Quietust wrote:
Yes, that would indeed be a problem - NES-NROM-128 is only designed to handle 16KB of PRG ROM, and you're trying to give it 32KB.

CPU A14 would normally go to pin #27 on the ROM - try cutting the current trace and then running a wire from the cart edge (you'll probably need to shave off the solder mask at the end of the pad) to pin 27 on the PRG ROM.

I should have figured that out in the first place. I studied my Mario 1 cart and noticed it routed that pin to a different place on the connector, so I soldered a wire from pin 27 of the ROM to pin 41 of the connector. It works!

I like how I don't have to worry about the sprite mirroring switch (since the game doesn't HAVE any sprites).

Also, what's a good method for stripping off the solder mask?

by Quietust on 2006-01-25 (#8550)

Computolio wrote:
I like how I don't have to worry about the sprite mirroring switch (since the game doesn't HAVE any sprites).

Er, mirroring doesn't apply to sprites - it applies to the background (which is what Bokosuka Wars uses)

Computolio wrote:
Also, what's a good method for stripping off the solder mask?

An X-acto knife should suffice, as long as you're gentle with it (scrape too hard and you might damage the copper underneath).

by Computolio on 2006-01-25 (#8587)

Quietust wrote:
Computolio wrote:
I like how I don't have to worry about the sprite mirroring switch (since the game doesn't HAVE any sprites).

Er, mirroring doesn't apply to sprites - it applies to the background (which is what Bokosuka Wars uses)

erm uh whoops

It's been a while since I've had to worry about that stuff. The last time I've ever dealt with PRG/CHR files was back in the PasoFami era.