IDE hard drive on original IBM AT?
ard at p850ug1.demon.co.uk
Thu Jul 14 17:46:37 CDT 2005
> Hello all,
> I have two "true-blue" IBM ATs, both the early motherboard revision.
> I have the following questions:
> - Is it possible to use an IDE hard drive instead of MFM? I have
> tried several different drive/controller combos, and nothing works so
> far :-( . The drives are small ( < 100 MB), so it's not a geometry
> issue (at least, I don't think so :-) )
> - Is anyone running an early rev. AT with an IDE drive? How did you do it? :-)
Alas I am running a later motherboard version here (8MHz clock), but I
had no problems plugging in a combined floppy and IDE hard disk controller
card and linking it to an IDE drive.
There were 2 things I did to get it 'right' although neither were
essential. One was to overlay the top 8K of the system ROMs with EPROMs
(this was a minor motherboard mod) so I could have a more suitable
geometry. The other was to add a kludgeboard (a few TTL chips) to the IDE
controller to operate the drive-in-use LED on the front of the machine.
The IDE drive I used didn't have an obvious output for this.
The IDE interface was designed to be software-compatible with the IBM
PC/AT hard disk controller card, so there shouldn't be problems. Note I
said 'shouldn't', not 'won't'. What exactly happens when you replace the
MFM controller with the IDE one?
More information about the cctech