19 May
2006
19 May
'06
5:30 p.m.
-----Original Message-----
From: cctalk-bounces at classiccmp.org
[mailto:cctalk-bounces at classiccmp.org]On Behalf Of Chuck Guzis
Sent: Friday, May 19, 2006 8:14 PM
To: cctalk at classiccmp.org
Subject: Re: ST-412 interface specification
Your biggest problem is going to be providing the serial raw data stream
support. That is, taking fully-decoded data and providing a high-speed
serialized MFM signal for reading and doing the reverse for writing. It's
usually a lot simpler if you can ditch the old MFM controller and tie in a
modern IDE drive directly.
Here is the situation. I have many older systems that only support the ST-412 standard
drives. Most use a WD-1005HDO style controller to talk to the machine's bus. I also
have several that use a custom controller to interface the system bus directly to ST-412
(without the WD-1005HDO). I'd like to continue using these systems, but I'm
quickly running out of working drives.
I do have the specifications for the system bus, but most of the software interface is not
documented. I would need to dissasemble the executables to figure out what is going on.
What I interpret what you said above to mean is that the interface between the controller
card and the ST-412 drive is not simply a digital interface. It is acutally the MFM stream
bi-directionally, and that the controller is what converts this to the system required
digital stream, and the systems digital stream to the MFM stream.
Is this essentially correct?
I did find the OEM manual for the 412 on the bitsavers archive. I'll start reading it
over tonight.
Kelly