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

From: Don Maslin <donm_at_cts.com>
Date: Wed Sep 29 17:31:03 1999

On Wed, 29 Sep 1999, Tony Duell wrote:

> > Now, do you mean Tracks, or Tracks per Inch? TPI is the density of the
> > tracks themselves, with 35/40 track 5.25 inch drives usually used 48TPI.
>
> 8" drives were also normally 48tpi (and 77 tracks/side)
>
> > 80-track 5.25 inchers (720K & 1.2M) used 96TPI, and all 3.5" drives that I
>
> There were also some 100tpi 5.25" drives. Micropolis made them (for what
> reason %deity only knows) and Commodore used them in things like the 8050.

Tandon made some also. Some of the Vector Graphics machines used them.
I have been told that these were an early attempt at "quad density" that
was soon dropped in favor of the 2x48(96)tpi format.

                                                 - don
 
> > know of are 135TPI. I don't recall what TPI the old 2" drives in the Zenith
>
> Is it 135tpi or 3/16mm between tracks (which works out at 135.46666
> (135+7/15) tpi? I would suspect the latter, actually, based on the
> manauls (and measurements) for a Sony drive I repaired a few months back.
>
> -tony
>
>
Received on Wed Sep 29 1999 - 17:31:03 BST