[net.micro] ds vice ss disks

kevinw%su-dsn@sri-unix.UUCP (11/23/83)

the only real difference between ds and ss disks is that the manufacturer
says that they are something different and asks for more bucks for them.
when you buy a ds disk they are claiming that they have tested both sides
and that they are ok.  when you buy a ss disk you are only getting a disk
which has been tested on one side -- not both -- thus they are making no
statement at all about the other side.  typically they are both perfectly
good, just don't expect the manufacturer to tell you that (and lose money?).
some ds disks which do not pass are sold as ss disks, but they are marked
by a pin hole somewhere on the disk (i believe) to signify that they failed
some kind of test.  if you REALLY need guarenteed (well, sortof) ds disks,
then by all means buy ds disks (i did just to be completely safe), but
they probably aren't worth the extra money unless you can't afford to lose
one.

cheers,
(and TANSTAAFL...)
  -- Kevin
     kevinw@su-dsn

ABN.ISCAMS%usc-isid@sri-unix.UUCP (11/23/83)

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

robison@eosp1.UUCP (11/28/83)

It's just as likely that ss disks are disks that FAILED the ds
test!  You take a risk when you hope to use both sides of ss disks.

				- Keremath,  care of:
				  Robison
			          decvax!ittvax!eosp1
				  or:   allegra!eosp1