PC10 NES adapter update

After a nights sleep and fresh attention, the rule of elimination told me which pin was wrong. Castlevania III was working perfectly, and as an MMC5 game it makes good use of CIRAM /CE and CIRAM /A10, so I knew it couldn't be them. Likewise, MMC3 games (SMB3) were working fine, as were most others.

The games not working were all old(er) UNROM games, that use on-cart WRAM, disabling the NES's WRAM. They were all drawing squigglies where the tiles should be, and Duck Tales was actually drawing sprites properly. Suddenly it dawned on me, it can read WRAM, but not write the proper graphics to it, thereby displaying whatever random electrons happened to be stuck in there. Sure enough, CHR /WR wasn't hooked up.

Now everything is working great, for the most part. I'm seeing the odd bit of static, or a line here or there on certain games, but at this point I know it's simply dirty cartridges. All of MY games (the ones I've had since I was a kid) play great, because if I take care of nothing else, I take care of my games.

As a matter of fact, get this, my Adventures of Link cart still has my save game on it! Those batteries have a 5-10 year lifetime, and this sucker is 20+ and goin' strong! I was so clever at 12, to name my character "FARTSO".

Now, if I could only crack that security/instruction EPROM, so the game didn't have to display as Pro Wrestling, with Pro Wrestling instructions. Having it display as "Nintendo", with some sort of Nintendo instruction screen would be cool.

I need some sort of data analyser, I think, even if it's homebrewed. If I could just sniff the "unencrypted" data coming out of it, program that onto a new eprom, and remove the security chip altogether.. it's just crazy enough to work.

It's also probably time to start drawing up some prototypes and see if I can get some pro quality boards fabbed. I'm also thinking a dedicated 60 pin slot for famicom games is in order, so I'm not running some crazy daisy-chain of adapters.

I also ran pin 54 from the expansion port to the PC10s audio line, hoping maybe Castlevania III had buried within it the extra sound hardware the japanese version carries.. It doesn't seem to. Oh well, would have been a neat 20 year old easter egg if I'd found it. It has a pin there, and its wired up internally.. Maybe the PC10 doesn't work right, I should try wiring that up in one of my real NES's.

I got lazy working out the bugs, and wired PRG /CE, CHR /A13 and VRAM /CE straight to the connector, not to the bus driver. Right now it wont work with other game paks on the board (since it's always active on the bus, wackiness ensues when you try to play two games at once). I'll try and fix that tomorrow. Then I can write up a proper howto for other budding hackers, once I'm sure that works.