nesdev.org

Hey all, I'm looking over some stuff and am trying to do Castlevania Blood Moon. It uses the UNROM mapper 2 board which has a 28 pin mask rom. You have to use a 27c1001 eprom to make the game and it has 32 pins! If you look at the eprom conversions page on here it calls for lifting the 31st pin on the eprom so it must be able to be done. Are there UNROM boards with 32 pin mask roms? I have not found any if so. Any advice/help would be appreciated! Thanks

Seems that there's two boards that have a 256KB ROM so that there's all the pins:

http://bootgod.dyndns.org:7777/search.p ... 9+20+41+53

But with that said, I'd just suggest this board below. You'll need some other extra parts like a CHR-RAM and some other resistors and capacitors and such but nothing is hard or expensive to find at all.

http://www.retrousb.com/product_info.ph ... ucts_id=42

What you need to do (if you really want to use an UNROM donor) is convert the UNROM board to UOROM. It's not hard, I did it a few years ago.

Notice how the 32-pin socket protrudes from the board, since there are only 28 holes. That's not a problem at all, as long as you wire everything correctly. Also notice how you have to connect one pin from the 7432 to the higher address line of the ROM, since that address line doesn't exist in 128KB chips.

Unfortunately I haven't kept the exact instructions on how to do it, but you just have to make sure that the pins connect to the correspondent signals on the board, bending pins and/or cutting traces when necessary. And of course, that extra pin from the 7432 I just mentioned.

Right thanks for pointing me to the correct unrom boards for those 3gen! I've been wanting to try out some of Retrousb's stuff as well. Also, nice work Toku that looks awesome! If anyone out there knows a brief pinout for the 32 pin eprom to the 28 hole Unrom that would be greatly appreciated!! Something with just the leg numbers on the eprom.