> 
> Having had my pc164 turned off for a few days, tonight I turned it back on.
> 
> My prize for doing this was a "machine check" whilst probing ahc0.
> 
> Several 'init's later, plus a cold boot...
> 
> Now it sees ahc0 (but refuses to do anything with it) and gets other
> errors with ATA.  What's going on ?

mmmm, spikey power-supplies.

In relation to the ATA drives, have checked all cabled and tried them
on another machine?

What about the srm isacfg, does that look ok?