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From: ABN.ISCAMS%usc-isid@sri-unix.UUCP
Newsgroups: net.micro
Subject: Re: ds vice ss disks
Message-ID: <13959@sri-arpa.UUCP>
Date: Tue, 22-Nov-83 22:07:00 EST
Article-I.D.: sri-arpa.13959
Posted: Tue Nov 22 22:07:00 1983
Date-Received: Sun, 27-Nov-83 04:45:43 EST
Lines: 20

There IS a difference between single sided and double sided disks -- at
least in the 8" version.  (Someone out in NetLand told me this a while back,
and I had to actually hold up two to see this.)  It seems the sensing hole
in the cover is at a slightly different location for DS than for SS.
The SS hole is at about 12:30 (figuring straight up as 12:00), while the
DS hole is at about 1:00 just a few degrees further clockwise.  Holding up
two of them, with the actual little timing hole in the disk itself centered
in the cover hole, you can clearly see they do NOT line up.  I then looked
down inside my beautiful Morrow Decision I (love that machine!), and sure
'nuff, there are TWO (count 'em, 2) little brass sensors wired in right about
where those timing holes are.  The machine sure enough checks it out physically
and electrically to discover SS or DS.  Donno what would happen if I nibbled
that SS hole into an oval shape so it would activate that 1:00 sensor -- would
it think the SS now a DS disk?  

Anyway, there IS a real, physical difference, and the machine (8" drives
anyway) can sense that.

David Kirschbaum
Toad Hall