15 Sep
2015
15 Sep
'15
7:48 a.m.
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
sure.
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.
paul