On v12 (GH35-21 board) very poor bootrate with v112a code...
When unit is cold, first boot OK with any media, but after few minutes impossible to boot any backup.
I use sx28AC + 50MHz resonator with 33k resistor and 74hc73
2nd problem with matrixfix2 pic
If pic installed only red LED on, can't power on the unit! Sometimes plug off-on the power adapter no led (even red LED) i light, must wait few minutes and red LED light again!
If matrixfix pic removed only boot problems exists.
Older boards worked perfect with this chip and icerev112a code (GH35_11)
btw what zener you mean? I use 8x4148 diodes for diodefix.
But now pstwo only boot when unit is cold, not powered before. After 1-2 minutes, sx chip maybe disabled itself or something, because original disk boot without disabling chip and backup not boot anymore. (only insert ps2 disc or blablabla message)