SA1000 interface

From: Richard Erlacher <edick_at_idcomm.com>
Date: Tue Feb 12 19:27:16 2002

There are quite a few signals that are more or less the same, and the
connector is the same ... BUT ... there are differences which are, in fact,
quite subtle. The Quantum drives, for one thing, use a superset of the SA1000
interface. That means, among other things, that the Quantum drives, (if my
feeble grey cells don't fail me) among other things, provide a clock that's
synchronized with the data the drive recovers, which the Shugart drives don't
provide, on the data cable. Moreover, the Quantum drives have a
microcontroller that accumulates pulses and can slew the step rate up and
down. I don't remember whether it actually does that (that's the difference
between the ST506 and ST412 interface, BTW) but the capability is there. The
clock extraction is such a big help that I'd say it cuts controller design
effort in half.

That greatly simplifies controller design, and, will allow you to jumper
around the PLL, etc, on the controller if you like, since the drive recovers
the data more reliably than the controller's PLL in many cases. What's more,
it makes it dirt-simple to hack a 5-1/4" (5 MHz) controller to work with the
8" drive, simply by changing out the crystal that provides write data timing.
I don't believe that the drive provides that clock when the write-gate is
turned on, but a quick peek with a 'scope will tell you about that. That way
you can hook one of the things to a bridge controller of your choice and
simply patch (cut-n-jumper) around the clock extraction circuitry and use the
clock from the drive instead. The controller hardware, firmware, and host
adapter software won't know about it at all, so you'll have an easy time
determining whether they work properly.

Good luck!

Dick

----- Original Message -----
From: "Joe" <rigdonj_at_cfl.rr.com>
To: <classiccmp_at_classiccmp.org>
Sent: Tuesday, February 12, 2002 4:20 PM
Subject: SA1000 interface


> Today I picked up two 8" Shugart 851 floppy drives and two 8" hard
> drives. I checked the hard drives (Quantum 2030s) and they use the SA 1000
> interface. How similar is that to the interface for floppy drives? The
> control cable for each hard drive also connected to one of the floppy
> drives so they must share a good bit of the interface. Does anyone have a
> pointer to a good on-line description of the SA 1000 interface?
>
> Joe
>
>
Received on Tue Feb 12 2002 - 19:27:16 GMT