[Coco] So, does anyone know where to get disk drives?

[Gene Heskett]

On Monday 02 September 2013 14:14:16 Michael Graham did opine:

> On 09/02/2013 12:10 PM, Gene Heskett wrote:
> > I don't believe there is one for the 5.25" diskette, the QD has
> > another notch opposite the write protect notch.  AFAIK there is no
> > diff in the magnetic characteristics between the 48tpi rated DD disk
> > and the 96tpi rated disk other than a more critical surface scan,
> > probably done on 1 per 10,000 made basis.  But since I expect that
> > the worlds supply of disks has been made & we are just cleaning out
> > warehouse's in Sechwan, none of the currently available stuff has
> > been subjected to even that close a look unless its been preformatted
> > to messydos FAT12 stds.  Even that isn't fool proof, the verify read
> > takes 3x the time that the format write takes, so failed format disks
> > are likely not recycled because the time consuming read verify step
> > was skipped.
> > 
> > Cheers, Gene
> 
> I think there must be a difference in the magnetics, or else I wouldn't
> have such trouble using 96tpi disks in older 48tpi drives. At least for
> the disks I have, when I try to format a 96tpi disk in a 48tpi drive, I
> can't ever read it back.
> 
> --Michael

Because of the differing widths of the track, AND the mechanical 
uncertainty of track zero positioning from drive to drive, changing the tpi 
on the disk can be a problem.  For that reason any such re-formating should 
be preceded by a bulk eraser so as to start with a truly blank disk.
 
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Cheers, Gene
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