18 Jan
2011
18 Jan
'11
11:32 p.m.
On 18 Jan 2011 at 15:44, Shoppa, Tim wrote:
There's a difference between what the interface
doesn't require a
drive To do, and what the most common drive implementations actually
do.
Agreed. I've got a 5.25" floppy drive with the tranditional 34-
position SA-450 interface that can do buffered seeks. Similarly, the
Drivetec floppy drives were very complicated in that department, not
only using buffered seeks, but also embedded servo.
But the floppy interface only *requires* at a minimum, "step",
"direction" and "track 0"--and some drives don't even require
track 0
and a drive using the interface can be dumb as a stump.
I don't think anyone has mentioned that the SA4000 was remarkable in
that it was a hard disk that used a stepper motor as a positioner.
Up until that time, every hard drive I know of used either some sort
of servo or mechanical adder (e.g. Univac FASTRAND (okay, it's a
drum, but a movable head drum) or Bryant 4000). A hard drive using a
stepper was extremely unusual before the SA4000.
My own SA4008 uses a controller on a PC board that has nearly the
same footprint as the drive itself. It's pretty much all SSI/MSI TTL
and ends in a GPIB interface. No microprocessors/microcontrollers.
Cheers,
Chuck