Bulk Erase 8" floppies

From: Don Maslin <donm_at_cts.com>
Date: Wed Sep 17 15:25:01 2003

On Wed, 17 Sep 2003, Nico de Jong wrote:

> > >A hint : sort the floppies according to density. I would be rather p.....
> > >if I bought a stack of 20 floppies, believing they were DSDD, and I got
> > >some SSSD ones.
> >
> > Is there a way to tell visually if they are DS vs SS? Not all the
> > floppies have their original factory labels on them any more, and I know
> > there are some of each.
>
> I just checked some of mine, and there is not really "conclusive evidence". On top of that, some SSSD floppies were rejected DSDD's. The good thing is, that I've never seen a double sided that couldnt be used as single sided. The story behind this is rather remarkable: when we talk about 3740 floppies (i.e. IBM labelled), the f?rst track is always written as single-side single-density, as some drives and/or systems can detect the disk format and/or re-assign defective tracks. So, selling "unknowns" as SSSD should be safe, and if they get a DSSD or DSDD (yes, they exist!), they were just lucky.
>
> Nico

Quite the contrary! A quick glance at an 8" disk will tell you
its density by the position of the index aperature in the disk
jacket. A Single Sided disk has the aperature 7 degrees clockwise
of the 12 o'clock position, while a Double Sided disk has it
located 26 degrees clockwise of the 12 o'clock position.

In other words, SS is at about 1202 and DS is about 1307 hours.

                                                - don
Received on Wed Sep 17 2003 - 15:25:01 BST