On Fri, 22 Jan 1999, Pete Turnbull wrote:
> On Jan 21, 15:15, Don Maslin wrote:
> > Subject: Re: Reiability of wrong media (was: is out of 5-1/4" diskettes
> > On Thu, 21 Jan 1999, Tony Duell wrote:
>
> > > Don't forget that '720K' 5.25" disks also exist, although they're not
> > > common on IBM PCs. By that I mean 80 track, double density, double
> sided,
> > > 300 oersted coercivity. Most of those do not have the reinforcing ring
> IIRC.
>
> And they're pretty common on non-MSDOS systems. I far more 80-track DS
> drives than 40-track of any flavour.
>
> > > > 720K 5.25" v 360K 5.25": again, an issue of testing/certification,
> > > > similar to SS v DS. At least for a while, they were manufactured the
> same,
> > > > but were tested/certified for 48tpi or 96 tpi.
> > >
> > > I have had very little success in formatting 48tpi disks in 96tpi
> drives.
> > > As I mentioned earlier, this includes name-brands like 3M..
> >
> > Interesting! I have never had a problem using even generic 48tpi disks
> > at 96tpi.
> > - don
>
> Nor have I, usually. I tend to treat all double-density 5.25" disks the
> same. Some of the old ones I have were converted to be "flippy" 40-track,
> and some time ago I found one such without a label. Not knowing whether it
> really had been formatted flipped, I tried it out, using the
> by-now-standard 80-track DS drive and a two-step circuit, and found it had.
> "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!
If you wanted to press your luck, you should be able to expand it to four!
- don
> So I have a three-sided 40 track disk :-)
>
> > > > 3", 3.25": Many newbies will get sloppy in reference to 3.5"
> diskettes,
> > > > without realizing that there actually were 3" and 3.25" diskettes.
> 3"
> > > > were used by Amstradt, some non-US Canon?, and Amdek add-on drives
> for Coco
>
> There are also 2.5" disks, though the only ones I've seen were made by TDK
> for an early digital camera. Anyone remember the make? Canon?
>
> --
>
> Pete Peter Turnbull
> Dept. of Computer Science
> University of York
>
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Don Maslin - Keeper of the Dina-SIG CP/M System Disk Archives
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Received on Thu Jan 21 1999 - 23:58:57 GMT