On Sun, 23 Mar 2025, Tony Duell via cctalk wrote:
A = 40 cylinder single head
B = 40 cylinder double head
E = 80 cylinder single head
F = 80 cylnder double head.
Very few machines used an 80 cylinder single head drive, and I suspect
the -F wasn't much more expensive anyway. So the -E model is not at
all common
(I believe C and D were reserved for 77 cylinder (8"?) drives, G is 80
cylinder double head, high density (360RPM? -- 1.2MByte), and H is 80
cylinder double head high density (1.4MByte))
C and D might still have been intended for 5.25"; either they made some
and they didn't sell well, or they were waiting to see if there would
become a need. (in case Micropolis made a comeback, or Vector Graphics
decided to make a luggable with half-height drives :-).
Tandon made some somewhat rare Tm400-4M drives (not always marked with the
M!).
Note, that some kids, who weren't around before Y2K, now call half-height
drives, "Full height", and use "half-height" to refer to quarter-height or
other slim drives.
Were all of the FG (and even the G) dual speed, or did some rely on a
controller supporting a 300K bps transfer?
--
Grumpy Ol' Fred [email protected]
