Finally trying out the Romance Of The Three Kingdoms 2 board i socketed quite a while ago, I noticed binaries above 32 bytes wouldn't work with my EPROM emulator. I can only conclude that the PRG-ROM is not consistent with the other ones used on NES boards. I suspected that upon socketing I already noticed that the CHR-ROM seemed inconsistent.

So is there anyone out there who has made an MMC5 devcart (or even used the exact same board?) and could tell me the differences in the pinouts? Since I've already socketed the board, I'm not too keen on tracing it myself...

This is what I've been wanting to do for awhile. I'm not good enough at electronics yet though. I doubt neones made a MMC5 devcart as no one really has made an homebrewn NES programs for it + not many liscensed games were made for it neway. It seems to be the best mapper though. Someone might have made pinouts for i though (I doubt it).

Just don't give up eh. Good luck :-)

Yes, MMC5 is probably the most powerful mapper used on American NES games. It isn't used often in homebrew for two reasons:

1. Realistic homebrew developers must remember the cost of replicating the cart. While one could easily solder up something on the level of CNROM or UNROM with cheap 7400 series parts and a $1 PIC to handle the lockout defeat, the only way anybody outside Nintendo can get an MMC5 is by destroying an existing MMC5 game's board.

2. Does any emulator emulate the MMC5 exactly?

1. Yes, it is very costly, but the mere fact that it hasn't been done yet brings sort of a challenge to make an homebrewn MMC5 game and somehow get it to work on the real thing by making an MMC5 devcart.

2. Well, it seems Nestopia plays MMC5 games pretty well with pretty much no errors (and I've used pretty much all the MMC5 games to test this). I'm not sure if any other emulator currently supports it (but I wouldn't be suprised), but I guess emulator authors might see no point in emulating the "whole" thing as not many games (if any) used all the features that potentially it could support.

I know that blof on #nesdev is making a homebrewn with MMC5. And at this instant it seems I got up from bed and checked the #nesdev channel just 20 minutes after he left. I have no luck... :)

Hi! "blof" here :)

I built a ROTK3 MMC5 devcart today. Since my game now uses the extra WRAM, I only had an ELROM devcart, and you were having trouble getting yours working, I figured I'd check it out.

The reason for your trouble is because it uses 8Mbit ROMs (well, 8Mbit ROM pinned out NES ROMs). These are different from the 4MBit (512K) NES ROMs documented at nesdev.parodius.com. Those have the last three pins tied high to +5V. The 8MBit pinout uses the last three for (30)PRG A19, (31) PRG /CE, (32) +5V. You were likely tying the /CE to +5V, which was making the chip perminantly disabled.

Here you go:

---_---
PRG A17 - |01 32| - +5V
PRG A18 - |02 31| - PRG /CE
PRG A15 - |03 30| - PRG A19
PRG A12 - |04 29| - PRG A14
PRG A7 - |05 28| - PRG A13
PRG A6 - |06 27| - PRG A8
PRG A5 - |07 26| - PRG A9
PRG A4 - |08 25| - PRG A11
PRG A3 - |09 24| - PRG A16
PRG A2 - |10 23| - PRG A10
PRG A1 - |11 22| - (likely an /OE, but tied perminatly to GND)
PRG A0 - |12 21| - PRG D7
PRG D0 - |13 20| - PRG D6
PRG D1 - |14 19| - PRG D5
PRG D2 - |15 18| - PRG D4
GND - |16 17| - PRG D3
-------

The CHR ROM pinout is the same too (different from the smaller, documented ones)

Good luck!

THANK YOU!!! I always needed one of thems MMC5 pinouts.

Thanks! I'll check this as soon as I get home to Sweden. The way my socket is configured, I most likely just ignored the PRG /CE and only used the /OE, which explains a lot of things. It's still kind of strange how my 16 byte long test program (which uses a loop to produce a sawtooth wave thru $4011) would run fine on it though. The unfortunate part is that this means I'll have to do an additional DIP-TO-IDC socket or start cutting up and rewire the damn board itself. =/ ...but at least I can try out some of the neat MMC5 features.