floppy controller IC (was Re: Fixing a PET?)

From: allisonp_at_world.std.com <(allisonp_at_world.std.com)>
Date: Thu Sep 30 10:30:16 1999

> (1) I've successfully formatted DSDD diskettes to 1.2MB DSHD format. I have
> also formatted DSHD diskettes to DSDD 40-track and 80-track formats, with
> varying degrees of success, depending on how carefully I tracked WHERE they
> had been formatted.


That tells me not to use your drives.

5.25 standard density media is 300oersted ferrite based and the correct
1.2mb media is 700o cobalt media. To write the DSHD80 to DSDD40 will work
IF... you first degauss the media then format it on the 80tr drive using
the cobalt media. It's one of those, sure but it's not reliable things.

NOTE: wrte current on both media impacts precomp and peak shift big time
considering your dealing with 2:1 changes.

Allison

> Eric's comments about the emulsion placed on the media is quite correct. At
> some point, however, it became economically expedient to use the same
> emulsion in all of their (the diskette-makers') products as opposed to
> producing two different emulsions. That led to another period during which

This is only true for 3.5" media that is not 2.88mb and 1.2mb 5.25 as they
are distinctly different formulations. For the rest yes, all the same
stuff or very close.

allison
Received on Thu Sep 30 1999 - 10:30:16 BST