12" Floppy Disks
paulkoning at comcast.net
Tue Sep 15 09:48:45 CDT 2015
> On Sep 15, 2015, at 4:39 AM, Adrian Graham <binarydinosaurs at gmail.com> wrote:
> Morning folks,
> I've been contacted by a teacher who's looking for any information about
> 12" floppies. Am I imagining that they really existed? I'm sure I've seen
> one or seen adverts for them, maybe at Bletchley Park. Others he's
> contacted think he's getting confused with 12" laser discs but I'm not so
The PLATO IV terminals (the hardwired Magnavox ones, not the later microprocessor based ones) had an optional "Audio player". That used a floppy disk of about that size, storing analog audio snippets (in analog form, not digitized -- remember, this was around 1972). Seek was done by a pneumatic D/A converter, essentially. There were 128 tracks, each with 32 sectors.
Those disks had no sleeve -- you'd just slide the bare magnetic disk into the player mechanism.
More information about the cctalk