12 Dec
2005
12 Dec
'05
11:21 p.m.
The discussion of 3.5" floppies probably
wouldn't be complete wtihout
mentioning HP. What follows is a case of IIRC.
Sony had originally brought the 3.5" drives out as 40 track 600 RPM
drives.(OAD-1). While impressive with their shorter latency, the 600 RPM
Hmmm.. The original Sony drives were certainly 600 rpm units, but I
thought 80 cylinder ones were there from the start. There are 40 cylinder
3.5" drives (67.5 tpi), in fact I've just been working on one (the Epson
PF10 floppy drive unit for the PX8). I haev never seen a 600 rpm 40
cylinder unit, though
drive was not compatible with existing controllers.
HP adopted the Sony
3.5" format but standardized on a 300 RPM 80 track drive.
No. NP used 600 rpm drives. Both the 'original' full height ones with a
26 pin connector, as used in the 9121, 9122, 9123, 9133, 9114A, etc and
the half-helght ones used in the 9153 and 9114B. I am absolutely sure of
this (darn it, enough of them have passed my bench :-)).
Remember that HP drive untis were intellegent, they included the
controller, and communicated to the host via an HPIB or HPIL link. It
didn't actually matter what speed the disk turned at (the bit density is
the same on an HP 600 rpm disk as on a normal PC disk).
IIRC, HP only used 70 cylinders on single-sided units and 77 cylinders on
double sided units for user data. The remainder were used to replace bad
tracks (!). This was handled by the drive unit (HP's controller board)
rather than the host.
I suspect that all HP PC clones had 300 rpm drives, though.
-tony