TESTFDC usage

[Roy J. Tellason]

On Thursday 07 June 2007 01:07, Fred Cisin wrote:
> On Wed, 6 Jun 2007, Roy J. Tellason wrote:
> > So Dave,  what's the deal with those oddball 5.25" drives?  I'm
> > remembering vaguely some that were 96tpi,  and one (?) that was
> > supposedly 100tpi...
>
> Dave is testing the FDC, not the physical parameters of the drive.

Ok...

> 96tpi DSDD was common briefly, but was never used in the PC, except for
> the PC-JX.  To the disk controller, it is the same as a 3.5" "720K".
> Teac 55F, Shugart 465, Tandon TM100-4, Mitsubishi 4853, etc
>
>
> Micropolis came out with a 100tpi (77 track) 5.25" drive.  It never really
> caught on.  Tandon made a replacement drive for that - TM100-4M.

I *think* that CBM used one in one of their boxes too,  maybe the 8050?  It's 
been a while so I'd have to double-check that to be sure...

> With a few exceptions, the 96tpi formats cqan be done using a 1.2M drive.
> Teac 55FG is deliberately intende3d for both "720K" and 1.2M use.
> The only exceptions would be drive where the stepper switches to double
> stepping when in "low density" mode, or using a 250K or 300K data transfer
> rate.

Noted.

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