System Industries MSCP disk controller problem

Michael Sokolov msokolov at harrier.Uznet.NET
Thu Dec 3 14:48:30 AEST 1998


   Tim Shoppa <SHOPPA at trailing-edge.com> wrote:
> 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. The outer box in which the BA23 is mounted is made by Sigma,
the funny way the ESDI drives are mechanically mounted is clearly a Sigma
invention, the card connecting the BA23 backplane to the expansion
backplane in the outer Sigma box is made by Sigma, and so is another
totally unmarked card of unknown purpose (its presence or absence appears
to have absolutely no effect on anything). The system is not 100% 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).
   
> 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.)
   
> Then again, it might not be a repackaged WQESD, but instead a Dilog
> or Emulex.
   
   I'm 99% sure that it's neither Dilog nor Emulex. I have seen quite a few
Dilog and Emulex cards, and I think I should be able to detect them easily.
   
> 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".
There is a stack of narrow 24-pin DIP chips going from the top of the board
to right above the EPROM. All have stickers, suggesting that they are
programmable. The stickers have different 6-character codes on them, all
starting with "1583". Directly to the right from the last one there is one
more such chip labeled "SYS IND 1583W3".
   
   Actually, I was wrong about there being 2 switch packs. There are 3 of
them, one of 10 and two of 4. The 10-switch one is right above the chip
labeled "SYS IND 1583W3". In the top right corner (right next to row A
fingers) there is a 4-switch pack. All switches are ON. Directly behind it
there is a 16-pin DIP chip labeled "1583I1" (the only chip with a sticker
not mentioned before). At the top of the board directly to the left from
the 10-chip stack there is a 10 MHz oscillator, the only clock on the
board. Directly to the left from it there is the last 4-switch pack. All
switches are ON. Finally, there are 3 LEDs between the top handle and the
10-pin header. The top one is red and the other two are green.
   
> Some
> other switches also set the interrupt priority, and this being
> off can also confuse some tests and OS's.
   
   What's the correct priority for disk MSCP? Should it be different
between primary and secondary?
   
> 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.
   
   You know what, I just looked a little closer and noticed that in this
configuration (both 4-switch packs all ON, SW1-9 on the 10-switch pack OFF,
and SW10 ON) the controller responds not only to 160334 and 160400, but to
just about any address in the Q-bus I/O page (except 172150)! No wonder the
CPU screams about it! What the hell is going on? How can it possibly do
this? Is someone trying to port Plug-n-Pray to Q-bus? Is it something like
KFQSA with a separate address for each drive and everything soft-
configured?
   
   Sincerely,
   Michael Sokolov
   Cellular phone: 216-217-2579
   ARPA Internet SMTP mail: msokolov at harrier.Uznet.NET


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