HP drives

Chuck Guzis cclist at sydex.com
Tue Dec 28 14:17:41 CST 2010

On 28 Dec 2010 at 11:48, Holley, Michael wrote:

> The original Shugart SA400 minifloppy (August 1976) only allowed 35
> tracks. In early 1977 Wangco announced the Model 82 Micro Floppy that
> allowed 40 tracks with new media. 
> Here is a photo of both disks.
> http://commons.wikimedia.org/wiki/File:Verbatim_5.25_minidisk_tracks_1
> 97 8.jpg

I was about to mention that I seem to recall that the SA400 could 
indeed write and read 40 cylinders, to the best of my recollection, 
but that some early media didn't permit it.

And, to add a bit of stuff to the mix, the Micropolis 100 tpi 5.25" 
floppies used 77 cylinders, with cylinder 0 offset outward a bit from 
where a 96 TPI drive would put it.

And I don't recall how many cylinders the Shugart/Dysan 3.25" 
floppies supported.  40?  I could format one up and see...


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