Reiability of wrong media (was: is out of 5-1/4" diskettes

From: Ward D. Griffiths III <gram_at_cnct.com>
Date: Thu Jan 21 22:41:10 1999

Depends on what "advantage" you're looking for. Once upon a weird
history, there were some vinyl LPs made where you got two different
music sets depending on which groove the needle dropped into -- and
it was hard to pick either in advance as the record was turning. I
admit that this is hard to arrange with floppies, since you need to
count on _something_ being half a track off, and digital doesn't
compromise the way analog does. Although with Flippies -- I tried
them a few times when 5.25" SSSD were the standard at $30+ per
ten-pack -- my failure rates were too high, much higher than when
several years later I experimented with 35-track SSSD (rated)
diskettes in 80-track DSQD drives -- I formatted over 50 diskettes
rated for 86k in 720k drives and all were still readable more than
five years later. Flippies had the problem that when you were
reading the data from one side, the head-load pad or whatever was
scraping off the data from the other side -- single-sided drives
have little or no reason to be careful of the (supposedly unused)
coating on the wrong side of the disc.

Ward Griffiths
"the timid die just like the daring; and if you don't take the plunge then
you'll just take the fall" Michael Longcor

On Fri, 22 Jan 1999, Tony Duell wrote:

> > On Fri, 22 Jan 1999, Pete Turnbull wrote:

> > > "OK, so that's a flippy", I said to myself. A little later, I re-read the
> > > catalogue -- and got a different listing! I had inadvertantly catalogued
> > > side two, with the disk right-side-up -- and realised that the tracks must
> > > not line up, so side two had two sets of data, going in opposite rotations,
> > > with the tracks interleaved!

> > This can't be possible! Otherwise, why didn't someone exploit this to
> > make 4-sided diskettes??

> Because you don't gain any extra storage. Pete formated every other track
> on the disk using an 80-track drive (narrow heads). So in the end he had
> 80 tracks on each side (40 going in each direction). Since an 80 track
> drive can write 80 tracks anyway, there's no advantage in flipping the
> disk over.
>
> -tony
Received on Thu Jan 21 1999 - 22:41:10 GMT