CSA Derringer 030 - tuned and broken??

[Ilwrath]

My guess is that your RAM latency is also determined based on the CPU oscillator.  So when you doubled your CPU oscillator, you halved the latency to your RAM, thus putting either your RAM or perhaps a built-in MMU out of spec.  

Unless there is a jumper or trace to adjust this, I'm not sure how you'd fix it without hacking more stuff on the card, though.  

[Ilwrath]

The wrong way however would be to try to bypass the part where the 50Mhz is lowered to 25Mhz for just the CPU.

This would be the wrong way?  It probably would have been my first thought as to a fix...?  Of course, you may introduce problems with the processor attempting to access the bus in mid-cycle, and such.  Eh, I never was so hot at the hardware side of things.  ;-)

[Ilwrath]

The MMU is intregrated in the 68030 (if it isn't a "EC"-version).

Yeah...  Actually, I was thinking of 020's, not 030's.  But some 030 accelerators used the "EC" chip and then an external MMU.  It would be a fairly obvious unit on the board, though.  And would probably be identified as an MMU (and a 68xxx part number).  Most likely, it uses the integrated MMU on a full 68030.