nesdev.org

Hey,

Any shot in the dark chance of getting a schematic for using a SEROM pcb as an SLROM pcb? Mainly how to wire the extra PRG & CHR
lines so I can use dip32 eproms with 128k\256k for PRG & CHR like a SLROM instead of maxing out at 64k on PRG & CHR as the SEROM does. Just asking as I have some extra SEROM pcb's and currently no SLROM pcbs
Cheers,

Shawn

SEROM caps at 32kiB PRG. (Because it goes CPU A14 → PRG A14, skipping MMC1 A14). There also aren't any games that have more than 32kiB CHR either. Rewiring SEROM to SLROM will require soldering to the MMC1's pins 1,2,3,4,10,11. (http://wiki.nesdev.com/w/index.php/MMC1_pinout)

lidnariq wrote:SEROM caps at 32kiB PRG. (Because it goes CPU A14 → PRG A14, skipping MMC1 A14). There also aren't any games that have more than 32kiB CHR either. Rewiring SEROM to SLROM will require soldering to the MMC1's pins 1,2,3,4,10,11. (http://wiki.nesdev.com/w/index.php/MMC1_pinout)

Could you please go into a little more detail? Also I don't understand what you mean about the CHR caping at 32k. I assume you mean on the SEROM as I know alot of MMC1 games that use much more than 32k CHR data (hense the need for the larger SXROM style pcbs). I need to know where to wire the extra pins from a 32pin 27c010 eprom package to the CHR and PRG slots on the SEROM and\or directly to the MMC1 chip itself if you don't mind please.

nintendo2600 wrote:Could you please go into a little more detail? Also I don't understand what you mean about the CHR caping at 32k. I assume you mean on the SEROM as I know alot of MMC1 games that use much more than 32k CHR data (hense the need for the larger SXROM style pcbs). I need to know where to wire the extra pins from a 32pin 27c010 eprom package to the CHR and PRG slots on the SEROM and\or directly to the MMC1 chip itself if you don't mind please.

I'm uncomfortable giving you a list of pins-by-number to connect, I'd rather you figure out how to do it yourself. Everything you should need should be in these two pages on the wiki.

Because SEROM doesn't connect the MMC1 to PRG A14, you'll need to connect all the pins labeled PRG A14, A15, A16 (and A17 if you were wiring up a 256KiB PRG ROM) from the MMC1 to the PRG ROM, and because SEROM only has 32KiB of CHR already wired, you'll need to connect the pins labeled CHR A15 and A16 from the MMC1 to the CHR ROM. The silver lining is that because both ROMs on an SEROM board are only 32kiB, you don't need to worry about A16 being in the way.