Valter Giargia
2018-06-25 07:13:41 UTC
I too found this error.
in my opinion the setting:
set rom nodelay
causes a lot more of them
probably some test checks timed istruction sequences
in my opinion the setting:
set rom nodelay
causes a lot more of them
probably some test checks timed istruction sequences
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1. Re: MicroVAX 3900 simulator fails BIST sometimes?
(Mark Pizzolato)
----------------------------------------------------------------------
Message: 1
Date: Sat, 23 Jun 2018 14:11:46 -0700
Subject: Re: [Simh] MicroVAX 3900 simulator fails BIST sometimes?
alohasunset.com>
Content-Type: text/plain; charset="us-ascii"
I'm just curious - do we (well, I don't, but somebody) have source
listings for
ROM
is built from. Without regard to precise listings, the listings don't
actually
have a mapping of the test numbers (and sub test numbers) to specific
tests. The assignment of tests is magically built by small macros that
briefly
define PSECTs that each tests contributes a little content towards. There
must be some nice tool that can decode the resulting collection of test
numbers and map them back to particular tests. Maybe a special
interpretation of data in the link map might help get there, but how it is
done isn't particularly obvious.
ROM debugging is a very tedious process. You poke around in the
ROM binary and disassemble a section. Then you locate particular
instruction
Sequences in the listing. Or you do the opposite (start from the listing
and
look for instruction patterns in the ROM). You then put simh breakpoints
in
some ROM locations that you want to stop at. The presence of breakpoints
adds to Heisenberg variances since simh breakpoints are implemented by
checking instruction fetch addresses rather than modifying the target code
to
insert actual breakpoint instructions (which are architecturally
meaningful
within the VAX simulation). For most things Heisenberg doesn't come into
play, but timing calibration stuff is the exception.
Anyway, this problem is benign enough, and the lack of solid debug data
has it sitting there unsolved.
- Mark
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1. Re: MicroVAX 3900 simulator fails BIST sometimes?
(Mark Pizzolato)
----------------------------------------------------------------------
Message: 1
Date: Sat, 23 Jun 2018 14:11:46 -0700
Subject: Re: [Simh] MicroVAX 3900 simulator fails BIST sometimes?
alohasunset.com>
Content-Type: text/plain; charset="us-ascii"
Heisenberg effects mean that the problem is never seen
Yep, the uncertainty principle applies to software as well...I'm just curious - do we (well, I don't, but somebody) have source
the KA655 EPROM? Supposedly one of the other hex numbers in the "?53 2
0AFF 00 0000" message identifies the exact subtest that's failing. It
might beinteresting to know that.
The listings we have are for a close, but not precise, version that theROM
is built from. Without regard to precise listings, the listings don't
actually
have a mapping of the test numbers (and sub test numbers) to specific
tests. The assignment of tests is magically built by small macros that
briefly
define PSECTs that each tests contributes a little content towards. There
must be some nice tool that can decode the resulting collection of test
numbers and map them back to particular tests. Maybe a special
interpretation of data in the link map might help get there, but how it is
done isn't particularly obvious.
ROM debugging is a very tedious process. You poke around in the
ROM binary and disassemble a section. Then you locate particular
instruction
Sequences in the listing. Or you do the opposite (start from the listing
and
look for instruction patterns in the ROM). You then put simh breakpoints
in
some ROM locations that you want to stop at. The presence of breakpoints
adds to Heisenberg variances since simh breakpoints are implemented by
checking instruction fetch addresses rather than modifying the target code
to
insert actual breakpoint instructions (which are architecturally
meaningful
within the VAX simulation). For most things Heisenberg doesn't come into
play, but timing calibration stuff is the exception.
Anyway, this problem is benign enough, and the lack of solid debug data
has it sitting there unsolved.
- Mark
------------------------------
Subject: Digest Footer
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------------------------------
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