mmc3 chr rom wiring

This is an archive of a topic from NESdev BBS, taken in mid-October 2019 before a server upgrade.
View original topic
mmc3 chr rom wiring
by coinheaven on 2008-04-26 (#33027)
are there numerous ways to wire the chr rom on mmc3 repros? most of the time i use the guide on this site, but sometimes i get garbled graphics. all the pins are soldered and everything looks fine. i have been looking through old posts and it seems some people wire the pin 1 to pin 32. is this necessary? any other pins that could be wired to fix the graphics?

by Bregalad on 2008-04-26 (#33029)
No there is only one correct way to wire the chip, at least when it comes to data/adress pins.
When it comes to useless pins such as VPP, /PGM or such things wire them to VCC (pin 32) and you should be fine. If you get scrambled graphics you most likely did something wrong with the adress/data/control pins.

by coinheaven on 2008-04-26 (#33033)
Bregalad wrote:
No there is only one correct way to wire the chip, at least when it comes to data/adress pins.
When it comes to useless pins such as VPP, /PGM or such things wire them to VCC (pin 32) and you should be fine. If you get scrambled graphics you most likely did something wrong with the adress/data/control pins.


cool. what pins #'s are VPP / PGM?