Re: Using both sides of DS DD disks

[mjmahon@aol.com (Michael J. Mahon)]

Frank Townsend asked:

>I was reading the recent discussion about DSDD disks and disk notchers and
>saw a comment by Roy as follows:
>
>*************************
>> Now a further question is "Why are most DSDD diskettes only notched on
>> one side?".
>
>"Because a double sided disk drive doesn't have to have the disk flipped
>over."
>*************************
>
>I'm using Apple 5.25 disk drives.  Are these double sided drives?  If not,
>were there any Apple II double sided 5.25 drives?

Not made by Apple, though I seem to recall some third-party drive that
was double-sided.  Of course, only that drive could be used to read the
disks written on it.

>Alternatively, were DSDD disks sold that were pre-notched on both sides?

Not commonly, but I believe that some were sold--especially for the
"flippy" disk market.

>Finally, is there really something about flipping a disk to record on the
>"wrong side" that endangers data on the "right side" as someone suggested in
>a previous post?

I've done it a lot, and never had a problem.  There are some theoretical
issues related to the disk liner picking up and then re-depositing debris
on the disk when counter-rotated, but I have never seen a case where
this was a problem.

In fact, I've never seen a "hard" error on an Apple floppy that I could not
locate visually by turning the disk in the sleeve.  In the half-dozen or so
cases (out of a couple of thousand disks), a hard error was always
caused by a piece of sticky dirt on the disk (often able to be carefully
scraped off) or by a visible crease or indentation (not so easy to fix,
and the reason that any scraping must be done with hard backing and
considerable care).

Another problem I've encountered perhaps a dozen times is a disk
which has so much friction in its sleeve that it will no longer turn at
the proper rate for reading.  This problem is _always_ easily fixed by
carefully running the edges of the sleeve along the corner of a table
(skip the skinny parts near the opening) to spread the sleeve slightly.

Permanent errors on Apple disks are rare and visible--worthy of framing!

-michael

Check out 8-bit Apple sound that will amaze you on my
Home page:  http://members.aol.com/MJMahon/