For those who have not heard of this particular recent project, I'm trying
to disassemble the 2K controller ROM in a Commodore D9060 IEEE-4888 hard disk.
Inside the box are a C= board with two 6502s, shared RAM, an IEEE interface
and a SASI interface. The drive mechanism is a Tandon TM602S (5Mb, D9060)
or TM603S (7.5M, D9090). In between is an OMTI 25011 SASI host adapter.
I'm attempting to understand the ROMs enough to either change the drive
geometry to something like an ST-225 (since they are so plentiful) or to
complete the code on the "DOS board", as it's called, to issue SCSI-1 commands
and drive an old 40Mb-200Mb drive at the limit of the Commodore DOS 3.0
physical size (~16Mb, IIRC).
To that end, an understanding of the OMTI would be essential. Does anyone
out there have docs? I have (badly blurred) copies of the schematics, but
no software info. I particularly need to know reads, writes, sense packets
and formatting packets as the OMTI implements them. Most important is to
learn how reduced write current and write precomp cylinders are set. If it's
a command, then that's easy to change. If the OMTI makes assumptions, then
it's not so easy.
I now know where in the code the drive geometry is set; I just don't know
how to affect RWC and precomp, even if I do patch the number of heads and
cylinders.
Thanks,
-ethan
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Received on Fri Oct 08 1999 - 23:59:17 BST