tried making repros of Dezaemon translated and PR8 using american SNROM carts. they run but seem unable to either write to sram or read back what was written. I followed this guide: http://hackitup.tumblr.com/post/1920173 ... o-sxrom-to
this is how I did the 32K ram:
pin 1 (a14) -> mmc pin 10
pin 20 (/CE) -> 7404 pin 2
pin 26 (a13) -> mmc pin 9
inverter:
pin 1 (1A) -> mmc pin 6
pin 2 (1Y) -> ram pin 20 (see above)
pin 7 -> prg pin 30 for 5v (convenience)
pin 14 -> prg pin 16 for gnd (convenience)
ram pin 1 is bent up so it's isolated. pretty sure I cut traces to ram pins 20 and 26 to isolate them rather than bending due to limited room. I checked for continuity and they should not be connected to the old pins anymore.
prg a18 is not hooked up but I think that's fine for both of the roms I tried, neither is 512K.
anyone see any issues with this?
mmc1 pinout for quick ref: http://wiki.nesdev.com/w/index.php/MMC1_pinout
this is how I did the 32K ram:
pin 1 (a14) -> mmc pin 10
pin 20 (/CE) -> 7404 pin 2
pin 26 (a13) -> mmc pin 9
inverter:
pin 1 (1A) -> mmc pin 6
pin 2 (1Y) -> ram pin 20 (see above)
pin 7 -> prg pin 30 for 5v (convenience)
pin 14 -> prg pin 16 for gnd (convenience)
ram pin 1 is bent up so it's isolated. pretty sure I cut traces to ram pins 20 and 26 to isolate them rather than bending due to limited room. I checked for continuity and they should not be connected to the old pins anymore.
prg a18 is not hooked up but I think that's fine for both of the roms I tried, neither is 512K.
anyone see any issues with this?
mmc1 pinout for quick ref: http://wiki.nesdev.com/w/index.php/MMC1_pinout