MSCP Spec questions

From: Pete Turnbull <>
Date: Mon Jan 19 15:44:41 2004

On Jan 19, 9:14, Patrick Finnegan wrote:
> So, is there a document anywhere that explains the 'programmatic'
> interface to MSCP-type controllers (or for any particular
> And I'm looking for disk MSCP not TMSCP. Basically, I'd like
> that explains the registers, command packets, etc. for hardware like
> RQDX3 or KDA50 or...
> Any help is greatly appreciated. I tried with little luck on google
> last night to find thist kind of stuff.

What you need is the "UDA50 Prograsmmer's Doc. Kit", QP-905-GZ. It's
not really UDA50-specific; I last used it to figure out what was wrong
with the DU: driver in RT-11 5.01, such that it wouldn't work with an
RQDX3 (DEC didn't follow their own protocol properly, was the answer,
and the bug happened to get past an RQDX1 but not some other

Mine is labelled "First Edition April 1982" and consists of:

AA-L619A-TK Ver.1.2 MSCP Basic Disk Functions Manual (approx 170pp)
AA-L620A-TK Storage System Diagnostics and Utility Protocol
 ( 46pp)
AA-L621A-TK Storage System Unibus Port Description (58pp)

The first deals with MSCP itself; gives an overview, a bit about the
comms side of it, algorithms, message formats, and a subset of commands
for disks. The second deals with DUP, which is what's used for
diagnostics and formatting. The last is about the port driver, which
you can think of as the layer under the class driver (MSCP/DUP).

Has the MSCP patent expired, or do you still need to license it?

And can you get copies from DEC/Compaq/HP, and if not, do they come
under the permission DEC gave to make copies?

Pete						Peter Turnbull
						Network Manager
						University of York
Received on Mon Jan 19 2004 - 15:44:41 GMT

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