Converting TLSROM to TLROM

Hey guys, just getting started with making repros. Unfortunately I was a bit hasty in getting my materials together and purchased 10 copies of NES Play Action Football, which is TLSROM and not TLROM. :/

Doing some research around these boards and elsewhere, it seems as though I can convert the boards by cutting the connection between MMC3 Pin 12 (CIRAM A10) and CHR Board Pin 22 (CIRAM A10), instead connecting MMC3 Pin 10 (CHR A17) to CHR Board Pin 22. This info I found in a few places, including the NES Dev wiki (http://wiki.nesdev.com/w/index.php?titl ... edirect=no).

This is in addition to following the guide for using EPROMS (from the TKROM instructions here: http://nesdev.com/NES%20EPROM%20Conversions.txt):

PRG socket:
Bend up pins 1, 2, 24, 30 and 31 (or cut tracks 2, 24, 30 and 31)
Solder pin 2 to hole 24 (A16)
Solder pin 24 to GND (OE)
Solder pin 30 to hole 1 (A17)
Solder pin 31 to hole 2 (A18)
CHR socket:
Bend up pins 1, 2, 22, 24, 30, 31 (or cut tracks 2, 22, 24 and 30)
Solder pin 2 to hole 24 (A16)
Solder pin 22 to hole 31 (CE or CHR /A13)
Solder pin 24 to hole 2 (OE or CHR /RD)
Solder pin 30 to hole 1 (A17)

I have my NES screwdriver coming tomorrow, hope someone can let me know if this will actually work.

Reading more, I realize I may run into an error with mirroring? According to NesDev Wiki (http://wiki.nesdev.com/w/index.php/Mirroring), to configure a cartridge board for horizontal mirroring, connect PPU A11 to CIRAM A10, and to configure a cartridge board for vertical mirroring, connect PPU A10 to CIRAM A10. This refers to connections on the PRG chip, right?

Your initial assessment is correct. The MMC3 supports changing the layout at runtime.

You only need to connect CIRAM A10 to PPU A10/A11 for games that expect fixed mirroring.

(The Picture Processing Unit connects to the Character ROM; the CPU connects to the Program ROM )

If you get it working let me know. I just posted this topic. It is literally 4 threads below yours. I even posted a pic and it still has messed up graphics.

Don't waste your time, use the shells if they are clean and ditch the boards.

Hey, I think I screwed up! Is it possible to use a 28pin (512KB) eprom for a TLROM game, or do I absolutely need a 32 pin board?

28 pin 'PROMs cannot be bigger than 64 KiB: 28 pins - 2 for power and ground - 8 for data bus - 2 for control lines = 16 address lines remaining

A 27C512 is a 512 kibibit 'PROM, or 64 KiB.

You can't use a 64 KiB EPROM to make a game that was originally designed for TLROM, but you can probably use it to put a TBROM, TEROM, or TFROM game on your board.

You can if you double the size.