First of all if "Rainbow mod" is not another name for "Mode Select Hack" then sorry for posting in the wrong section.
like your SNES mod : http://www.bradsprojects.com/electronic ... tHack.html
Do you think it could be improved by adding region selection with control of pin 4 of the F413 chip (to play import games) and still with one 16f628a ?
Can we perform PWM (Pulse Width Modulation) on LEDs with 16f628a ?
If yes, it could be cool to see selected mode as something like this (or another colors table, the following one was the first popping up in my mind) :
Red 50 Hz / original region
Green 60 Hz / original region
Red/Blue* 50 Hz / region free
Green/Blue* 60 Hz / region free
*A combination of 2 colors glowing successively and progressively.