i know most of my drives i had to remove the jumper to put it into single master mode before it would work on my Mac.
i tried master with slave present mode but it would not work.
i think that if you have the jumper in on master that is master with slave present mode and it could be messing up how the Mac reads the drive
have you tried other drives in the machine? If its not even picking it up with anything, i'm thinking there could be a remote possibility that the Mac's IDE controller could be dead. Also, check that the jumpers are set right on the drive, check that its set to Master (MA), not Slave (SL) or Cable Select (CS).
It has three pairs of pins on the top of the drive, and i tried it with each of the pairs. (I don't recall trying it without anything at all jumpered... might be crazy enough to work... maybe I should give that a try...)
As to using another drive, I'll have to see if I can dig up another one to try in it. My gut is telling me it's the controller that's dead... since CDs and the floppy drive still work properly (since they seem to use SCSI instead of IDE).
If you can, try hooking it (the drive) up to something else via IDE (rather than USB) just to confirm that it's OK. If it is then maybe try a different IDE cable in the 638 and try again
I couldn't try it in any of the other old Macs I have, because they all have SCSI connections instead of IDE. I would have tried a new cable, but I don't see a way to do that. The cables go through some kind of weird bracket thing instead of using a regular IDE cable.
