Diskette size

Fred Cisin cisin at xenosoft.com
Fri Jul 21 14:42:49 CDT 2017

On Fri, 21 Jul 2017, Paul Koning via cctalk wrote:
> Interesting.  Another example, slightly later, is the audio unit of the 
> PLATO IV terminal (1974 or thereabouts).  It uses a rather large disk, 
> perhaps 10 inches diameter, brown oxide, no grooves.  It's a random 
> access device, with 128 tracks.  Each track has 32 sectors; a given 
> audio clip can be up to 127 sectors long (though I'm not sure what 
> happens if it's more than 32 sectors -- does it switch tracks?  Seems 
> unlikely).
> The track seek is done with a binary encoded pneumatic cylinder 
> assembly, 7 cylinders -- low order stroke is one track pitch, next is 2 
> tracks, next is 4 tracks, etc.  So the binary track number would select 
> 7 air valves which would feed supplied "shop air" to one or the other 
> side of each piston, moving the read/write head to the correct track.

Floppy? not rigid?

I actually do love to be proven wrong!
(so long as there are details like this!)

Are there any pictures?

I wonder whether I could get one of those disks?
(without depriving somebody with a machine from them
(shades of keyboard collecting?))
It's kinda moot.  I'm retired from XenoSoft, disks, even teaching.
And, I'm trying to come up with clauses for my will of whom to contact to 
haul off my crap when I croak.   (my sister would otherwise dumpster 

Grumpy Ol' Fred     		cisin at xenosoft.com

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