DEC RK07 drive interface specs wanted

From: Paul Koning <pkoning_at_equallogic.com>
Date: Thu May 13 11:57:52 2004

>>>>> "Brad" == Brad Parker <brad_at_heeltoe.com> writes:

 Brad> "Peter C. Wallace" wrote: ...
>>> use the board for a wide range of applications, resulting in
>>> higher production volume and lower cost. I know that a list
>>> member was designing a board like this. I don't know how far he
>>> got. But my offer

 Brad> I'm designing a simple board with a PIC cpu and a CPLD which
 Brad> should be able to emulate virtually any disk controller (given
 Brad> software).

 Brad> The idea is that the cpld holds a register set which the PIC
 Brad> and unibus can read/write and the PIC can be a bus master to
 Brad> read/write unibus memory.

That should do the job just fine for MSCP (except that this may be too
large a job for a PIC). For older disk controllers, this approach is
likely to be hard because touching CSRs causes actions to take place,
and often actions are tied to bits, not just to the whole CSR. You
may be able to emulate that in software, but it's likely to be tricky
because your CPLD will have to be more than just a register file.

I'd say that anything that was originally done as a microprocessor
plus register file would be no problem. That means (T)MSCP devices,
the DMC/DMR/DMP/DMV11 series comm controllers, the KMC11, and the Pro
hard drive controller. But if it started out as hard logic, a
microprocessor emulation wouldn't be as easy. That's why the
programming interface style changed quite drastically when
microprocessor control became interesting.

       paul
Received on Thu May 13 2004 - 11:57:52 BST