[Simh] MicroVAX 3900 simulator fails BIST sometimes?

[Mark Pizzolato]

This problem is not unique to you.  I have not been able to reproduce the problem with enough debug information to track down the details of the cause.  The problem report relates to the boot ROM's internal clock/timer diagnostic.  In all of my test cases, with debug information being gathered, Heisenberg effects mean that the problem is never seen.  :(

You could side step the problem if you:

1)      Didn't enable auto boot
AND

2)      In your configuration file, you have 'EXPECT ">>>" SEND "BOOT DUA0\r"' before your existing BOOT command.

This will work since, although the "Normal operation not possible" message has been issued, the error is not actually severe enough to inhibit system operation.  It just inhibits autoboot.

I haven't given up hope of eventually capturing the detail of the cause and thus fixing it.  Once I give up hope, I'll revert to the original simh boot ROM strategy that had this clock/timer test disabled.


-          Mark

From: Simh [mailto:simh-bounces at trailing-edge.com] On Behalf Of Robert Armstrong
Sent: Saturday, June 23, 2018 11:16 AM
To: simh at trailing-edge.com
Subject: [Simh] MicroVAX 3900 simulator fails BIST sometimes?

  I've found that on occasion the MicroVAX 3900 simh will fail the built in self test.   Just to be clear, this is the self test that's in the MicroVAX-III EPROM image that's failing; it's not VMS.

legato-hecnet.sim-73> boot cpu

KA655X-B V5.3, VMB 2.7
Performing normal system tests.
40..39..38..37..36..35..34..33..32..31..

?53 2 0A FF 00 0000

P1=00000002  P2=00000028  P3=00002712  P4=00D40077  P5=00000001
P6=FFFFFFFF  P7=00000000  P8=00000000  P9=00000000 P10=20051CE0
r0=00000007  r1=20140110  r2=6954A9F0  r3=0002FF6A  r4=6954A9FA
r5=2004E8F9  r6=00018678  r7=000186C8  r8=0001ADB2 ERF=80000000
30..29..28..27..26..25..
24..23..22..21..20..19..18..17..16..15..14..13..12..11..10..09..
08..07..06..05..04..03..
Normal operation not possible.


  Does anybody else have this problem?  It seems to be random and not easily reproducible.  It happens once every dozen restarts or so, but when it does happen I can just restart simh and it'll work fine the next time.

  It's a bit annoying because it makes the auto-restart of my emulated VMS system fail..

Bob

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