I think I've got an old Hard Disk 20 and it's a
SCSI device. I'll have to
find
the lid to see what it says on it, though. It seems to me that it's an
old MFM
drive with a customed up SCSI bridge adapter on it.
There are two different products with the name Hard Disk 20. One is the
Apple Hard Disk 20 SC and it is a SCSI device. There were also 40, 80 and
I think 160 mb versions (and maybe others in larger sizes).
BUT... predating that was a "Macintosh Hard Disk 20" that was not scsi.
Rather is was some drive (don't know what kind, but MFM seems sensible
enough) that used a special adaptor board that enabled it to plug into
the disk drive port on a bunch of the older macs. It was all enclosed
(drive, power supply, adaptor board) in one nice zero footprint beige
case (back when beige meant brown, and not grey like "beige" computers of
today).
They are two totally different drives, sold at two different time periods
(although, I do believe they overlapped for a while, until the SCSI
version completely replaced the disk drive version).
-chris
<http://www.mythtech.net>