System Industries MSCP disk controller problem

[Tim Shoppa]

>> This sounds a lot like the Webster WQESD, which was repackaged
>> and sold by many different folks (Sigma, DSD, Qualogy, American
>> Digital, etc.)
>   Quite possible, since this funny Xerox system has a lot of Sigma
>components.

I regularly work with "PDP-11 systems" now that don't have a single
DEC component in them.  CPU by Mentec ( http://www.mentec.com/ ), 
disk controller by Andromeda ( http://www.andromedasystems.com/ ),
async and parallel I/O by the Logical Company ( http://www.logical-co.com ),
etc.  What else are commercial developers left to do now that
DEC (after over a decade of trying to) has finally abandoned their
PDP-11 product line?  At least the other companies named are still
doing active support and (at least in Mentec's case) development!

> The outer box in which the BA23 is mounted is made by Sigma,
>...
>though. There also another 2-drive ESDI controller (that's the one that was
>at 172150 from the beginning) and a 9-track tape controller, both made by
>Emulex (QD21 and QT13, respectively) and both appear toast (I want to get
>rid of both).

You might be a bit hasty in casting these off, as you aren't having
the best of luck with the rest of the peripherals, either!
   
>> If it is a repackaged WQESD, SW9 on the 10-switch pack was originally
>> on, with SW10 and SW5-8 off, to put the CSR at 160334.
>> To set it to be 172150, you put SW10 on, and SW5-9 off.
>   Before I got your E-mail, SW5 and SW8 were ON and the rest were OFF
>(don't remember if it was the original position). I also tried SW10 ON and
>the rest OFF. In both cases the effect is exactly the same. At power-up the
>CPU screams, but then gives the ">>>" prompt. Trying to read different
>locations with the E/P/W command (the Q-bus I/O page is mapped at
>0x20000000 in the VAX address space), I see that the card responds somehow
>to 160334 and to 160400, but not to 172150. (I know that it's this card and
>not something else, since when I pull it out the CPU is happy and no one
>responds to these addresses.)
>> Is there a 10-pin header on the card edge?  Can you describe the
>> positions and types of "big chips" on the board?
>   This is a quad-height board. All components are thru-hole and all chips
>are in DIP packages. There are no 4-sided chips or surface-mounted
>components. Hold it with the component side up, the fingers to the right
>and the handles to the left. On the left (handle) side there is a row of
>shrouded header connectors. From top to bottom, they are: 10-pin (connected
>to something, but purpose unknown), 34-pin (ESDI control and status), 20-
>pin (drive 0 data), 20-pin (drive 1 data), 20-pin (drive 2 data). Directly
>behind the bottom 20-pin header there is another 20-pin header for drive 3
>data. The biggest chip is a 48-pin DIP labeled DP8466AN (National
>Semiconductor as far as I can tell), and it's right behind the drive 3 data
>connector. There are two AM2901CPCs behind the 34-pin connector. There is
>one 28-pin EPROM right about in the center, shifted downward a little. The
>ROM size is obscured by the sticker saying "ESDI V2.41 9901-8918 REV.A".

That clinches it - it's a Webster WQESD, running Wombat V2.41.

9901-8918 is evidently the SI part number for the complete system.
It's a bit confusing to go from the SI part number because they all
begin with "9900" or "9901"!
   
>   What's the correct priority for disk MSCP? Should it be different
>between primary and secondary?

A summary of the WQESD switch settings, and the various ways in which
you can invoke Wombat, lives at:

 ftp://sunsite.unc.edu/pub/academic/computer-science/history/pdp-11/hardware

as the file "WQESD.txt".
   
>> As to your power-on self-test woes, you're going to have to tell
>> us what's in the system and what slot it lives in, as well as what
>> sort of backplane it's all in.
   
>   The outer box is Sigma. It provides funny mounting for 4 ESDI drives, an
>expansion Q-bus backplane, and a big bay for a BA23. The BA23 contains the
>CPU, the memory, and all peripherals except the controller in question.
>First comes the KA650 CPU. Then two MS650 memory modules. Then DELQA,
>DZQ11, TQK50, and the Sigma Q-bus extender card. The latter takes the Q-bus
>into the expansion backplane, where the controller in question is the only
>device. It's in the expansion backplane instead of the BA23 because that's
>where the actual drives are. I have tried pulling the Sigma Q-bus extender
>card out and putting the ESDI controller right in the BA23 backplane, but
>this didn't change anything, so there is nothing wrong with the Q-bus
>expansion.

I'm willing to bet that you have severe Q-bus continuity problems,
especially now that you've told us that you have an expansion Q-bus
cabinet and that you've been randomly moving Q-bus cards around.
You have to tell us exactly which slot each card is in, and preferably
the original configuration as well (the Sigma backplanes have different
wirings than the common DEC ones.)

Is the "BA23" indeed a real DEC BA23, and not the Sigma "clone"?
The sigma 5.25" 9-slot backplanes have very different backplane
wirings (and, indeed, putting a DEC dual-wide Microvax CPU into
it will very likely cause damage.)

As a start, work just with the BA23.  Put the CPU in slot 1, with
the two memory boards in slots 2 and 3.  Put the WQESD in slot 4.
Have nothing else plugged in at all - especially not the boards
that jumper the two backplanes together.

Set the DIPswitches on the WQESD as follows:
10-switch pack: Switches 1-2 off, 3 on, 4-9 off, 10 on.
4-switch pack near the edge connector: 1-3 on, 4 off.
4-switch pack near the handles: 1-4 on.

Then try to start up wombat with the following sequence of console commands:

Microvax II:
Halt the processor
U
I
D/P/W 20001F40  20
D/L 20088008 80000002
D/W 20001468 AC
S 400

If this doesn't start Wombat, tell us *exactly* what the error message
produced is.

--    
 Tim Shoppa                        Email: shoppa at trailing-edge.com
 Trailing Edge Technology          WWW:   http://www.trailing-edge.com/
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