Date   : Wed, 15 Jan 1986 08:04:00 EST
From   : Kushall.henr@XEROX.ARPA
Subject: Re: 40 track drives on Apple CP/M

Many of the early micro computer 5.25 inch floppy disk systems were
based on the Shugart SA400 "mini floppy" drive. (For a while they were
the only maker ie 1975) This was the original 5.25 inch drive. The SA400
could only have a maximum of 35 physical tracks. If you attempt to step
to a track >34 the CAM follower would lift out of the grove.

Later Shugart updated the drive design to 40 tracks, and 40 tracks has
been standard on 5.25 inch drives for quite a while now. I don't know of
any other companies that make 35 track drives. Shugart drives labled
SA400 are 35 track drives, drives labled SA400L are 40 track drives.
Also some early Shugart SA400's were single density. (I belive before
1977) The only way to tell these is by the serial numbers.

Ed Kushall