Interpreting Vaxstation 3100 memory error - test-drb@ccmp.vtda.org

27 Nov 2011

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Picked up a Vaxstation 3100 today at the SRCS meeting.  There is some 
minor corrosion on the memory and motherboard PCBs, some due to 
prolonged exposure to moisture, and some due to a leaking clock 
battery.  I've cleaned up the corrosion and it doesn't appear to have 
done any serious damage.

At POST it identifies itself as a KA42-A, which I believe makes it a 
Model 30.

Presumably it says VS42-A on the back of the box?

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I'm getting error messages from the POST and I'm unsure how to interpret 
them -- the manuals have not been 100% clear.  Here's what I get:

KA42-A  V1.3

F...E...D...C...B...A...9...8...7...6...5...4...3_..2_..1?..

  ?  E  0040  0000.0005
  ?  C  0080  0000.4001
  ?  B  0010  000C.0081
??  1  00C0  0011.700E

The (E) error I expect since there's no clock battery.  The (C) is also 
expected since I don't have a keyboard/mouse plugged in (just using the 
serial console).  Similarly, (1) is also expected since I don't 
currently have the ethernet interface hooked up to anything.

(B) is what's confusing me -- my understanding is that a single question 
mark indicates a "soft" error, described in the manual thus: "Usually, a 
question mark (?) in the power-up summary indicates a soft error and the 
system may be usable without replacing any FRUs."  OK.  What does that 
mean for memory, and how do I interpret the error code?  I know that the 
"000C" part indicates the amount of memory installed -- what does
"0081" 
mean in this context, and should I be concerned?

Perhaps it is complaining about an error which is correctable by ECC?

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For further reference, "test 50" gives the following for memory:

  ? MEM      000C.0081
       00400000

I've had a quick look in Vaxstation 3100 Maintenance Guide (EK-285AA-MG-001)
and it doesn't seem particularly clear to me either. It doesn't seem to
mention 0081 at all.

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The machine does boot (VMS 6.0 off of two very noisy 104MB drives) and 
it seems to work OK, though I haven't stressed it much yet.

Under VMS, does SHOW ERROR or ANALYSE /ERROR (given an early enough version
of VMS) shed any light?

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Any suggestions here would be much appreciated.

The manual does suggest running the field service system exerciser
(TEST 80000106 B) with a loopback connector on the serial port. Assuming this
is an MMJ socket, you just need to loop DSR to DTR (ie the two outer pins),
RXD to TXD and the two grounds in the middle to each other.

If any of the memory is on an expansion board, try removing it and repeating
the test to see if the problem is on the system board.

(I've had some battery corrosion problems in a VS3100. It doesn't look too
severe but test B seems to fail in the middle and go back to the start, repeating
over and over. I must get around to making a better attempt to clean it and
check the traces.)

Regards,
Peter Coghlan.