8 May
2016
8 May
'16
2:02 p.m.
On 2016-05-08 5:49 PM, Chuck Guzis wrote:
On 05/08/2016 01:30 PM, tony duell wrote:
Are you sure about the SA-400 being used in 5150s? All the ones I ever
saw where Tandon TM-100s which look very much like them and I saw lots
as a support person in an IBM lab in the early 80s. They have the same
sort of motor setup to turn the diskette, but use a different head
positioner. The TM-100s used a stepper with a taut band positioner.
Paul.
They are considerably better than the Shugart
drives with the plastic
disk with a spiral groove for the head positioner....
Ah yes, the SA-400. When I
was evaluating one, I wondered if Shugart
was really serious about the things. Doubtless some engineer at Shugart
was quite proud of himself for designing a ball-bearing follower for the
spiral groove. Marks for being cheap.
Oddly, my own troubles with the SA-400 (believe it or not, this was used
as the original IBM offering for the 5150 drive) were with the tach
circuit. Mine blew a small inductor.
Among all of the 5.25" FH drives offered at the time, my vote still goes
to Micropolis for designing the Sherman tank of drives. Leadscrew
positioner with multiple steps per track. Probably among the most
expensive 5.25" drives also.
To their credit, Shugart did have the best hub-clamp setup.
--Chuck