Feline
Many thanks for all of that. I was, in fact, going to try the W95 route 'cos I have a feeling that that was the OS the last time I tried a similar combination (which worked!).
I haven't tried the drivers as my 'bible' states categorically that if the only devices are hard drives, the ASPI drivers are not required. Still, it won't do any harm to try. Everything else is as you suggest, with the host BIOS doing it's thing correctly and identifying the D drive - but DOS doesn't (DOSN'T??) Time for another lie-down !
I shall test the waters and report.
Again many thanks