[Simh] Simh Digest, Vol 173, Issue 5

[Valter Giargia]

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

2018-06-24 18:00 GMT+02:00 <simh-request at trailing-edge.com>:

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> Today's Topics:
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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
> From: Mark Pizzolato <Mark at infocomm.com>
> To: "bob at jfcl.com" <bob at jfcl.com>, "simh at trailing-edge.com"
>         <simh at trailing-edge.com>
> Cc: Mark Pizzolato <Mark at infocomm.com>
> Subject: Re: [Simh] MicroVAX 3900 simulator fails BIST sometimes?
> Message-ID:
>         <03006E3FC39B5A48AB9DBCCC101090A8343CCCF72F at REDROOF2.
> alohasunset.com>
> Content-Type: text/plain; charset="us-ascii"
>
> On Saturday, June 23, 2018 at 12:41 PM, Robert Armstrong wrote:
> > > Mark Pizzolato <Mark at infocomm.com> wrote:
> > >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
> listings for
> > the KA655 EPROM?  Supposedly one of the other hex numbers in the "?53 2
> 0A
> > FF 00 0000" message identifies the exact subtest that's failing.  It
> might be
> > interesting to know that.
>
> The listings we have are for a close, but not precise, version that the
> 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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> End of Simh Digest, Vol 173, Issue 5
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