I think I've located the problem, but not before tearing my hair out a little more.
It would appear to be my 4GB CF HD card or it's adaptor. I tested the new 1D.1 board and all appeared fine booting from the floppy PCMCIA utility...hurray I thought, cracked it. However after loosely assembling everything and booting from the HD, I got the dreaded CF0:NDOS once more. Knowing the only difference in hardware was the HD, I disconnected it and voila, it saw the CF0: perfectly. Interestingly the system sees CF0: if I use my old fashioned Hitachi 60MB HD
As an aside, after a few minutes the system became unstable and would lock up randomly. Checked everything and started swearing again
. Did a bit of research online and I found a couple of instances of 1D.1 giving the same symptoms with Apollo accelerators. One guy involved tried everything until applying the 1D.4 timing fixes, which cured the problem. I've just done the same and it's been running stable all afternoon
Now all I have to do is try another combination of CF HD to cure the original problem.