Clint Sharp ) writes:

It's more likely to work on a modern IDE drive IMHO, the boards are more
generic across a range and are not 'matched' to one HDA, lots of the old
MFM/RLL drives had 'SOT' components which were designed to match the
board to the HDA. ESDI and SCSI drives were more tolerant of a board
swap but drives of that era had boards with obtainable components so a
repair was also possible.

But the pre-IDE drives gave you a lot of access to the drive, since
the controller was separate. MOve the controller to the drive, as
is the case with IDE drives, and you don't have that low level access.

Pre-IDE, the bad sectors on the drives would be written on the drives,
and you'd tell something (I guess the formatting software but I never
really had any experience with pre-IDE drives) to avoid those sectors.
With IDE drives, the drive itself keeps track of such things.

ANd this is what came of the thread some months back. It was pointed
ou that the eeprom on the board was likely keeping track of those bad
sectors, and when the board was swapped, it no longer matched the
state of the new drive.

Michael