Originally Posted by Daedalus
Are you sure it's not simply that the CPU doesn't work at that speed?
I'm in contact with him, because it looks like the "red screen behaviour", which I have considered a cosmetic and not a functional problem so far, is causing the hang. I have developed a CPLD-fix that may get his card running properly at 28MHz.
Initially, I developed the fix for the ACA1221EC, but it is now back-ported to the ACA1221 and ready for a try.