glitchy graphics!!

This is an archive of a topic from NESdev BBS, taken in mid-October 2019 before a server upgrade.
View original topic

glitchy graphics!!
by pivotman on 2010-03-08 (#57708)

Hi guys,

Im trying to make a bubble bath babes cart and It's glitchy as hell!

Im using 1 27c256 and 1 27c512 eproms

There both at 150ns

any one have any suggests on how to slove the problem.

by tepples on 2010-03-08 (#57713)

What donor board are you using? Stock CNROM and GNROM boards are designed for only 32 KiB of CHR ROM, and the CHR ROM of BBB is bigger than that. You'll have to modify the board to reroute CPU D2 through the 74HC161 before it will work.

Previous topic

by pivotman on 2010-03-08 (#57715)

tepples wrote:
What donor board are you using? Stock CNROM and GNROM boards are designed for only 32 KiB of CHR ROM, and the CHR ROM of BBB is bigger than that. You'll have to modify the board to reroute CPU D2 through the 74HC161 before it will work.

Previous topic

Hmm ok

Right so in order for this to work I need to,

Bend up D2 and Solder it to pin 47 on the pcb
Then bend up Q2 and bend up a15 and Solder them together.

Is that right?