SA1000 interface

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(a)cfl.rr.com> To: <classiccmp(a)classiccmp.org> Sent: Tuesday, February 12, 2002 4:20 PM Subject: SA1000 interface