PDP-11/45 RSTS/E boot problem

Fritz Mueller fritzm at fritzm.org
Mon Feb 4 11:34:47 CST 2019

> On Feb 4, 2019, at 9:13 AM, Jay Jaeger <cube1 at charter.net> wrote:
> If he hasn't already, if Fritz has more than one memory board, he might
> try swapping them to see if that changes anything.

I only have an 128kw MS11-L here to work with, unfortunately.  Its been through a bunch of recent troubleshooting (tracking down and replacing failed DRAMs).  I *think* its pretty solid at this point (also passing some of the hairier DEC diagnostics) but...

I'd be happy to try out a different memory board if anybody was interested in sending out a loaner?  (I'm in the SF Bay area).

> The issue I'd see with the MMU swapout idea would be finding one that
> would be ECO-compatible with the rest of the processor.

Yes; per previous email.

> Other things I might be tempted to try in order to coax more information
> out of the situation:
> 1.  Run the DEC system exerciser, if that has not already been done.

Done; passes consistently.

> 2.  Make a copy of ls, and see if the copy also fails
>    (different location on disk would mess with timing just a bit).

Also done; the copy appears to behave identically to the original.

> 3.  Use SimH to build a pack image with an instance of ls that is not
>    pure text (no -n or -i flag)
> 4.  Use SimH to build an ls that does/does not start the data segment
>    for ls at 0 (has / does not have the -i flag) [I have not looked to
>    see how ls would normally be built.]

These may yet be interesting experiments.

> 5.  Use SimH to gen a pack image with a kernel that is a not split I/D

The image I'm using is a /40-compatible one, built from the distro tape, the one that you get before going on to rebuild for /45. So, as Noel has reminded me, no split I/D.  But we could try the opposite experiment (build a pack customized for /45) and see if that's different?

The pain with that is that it takes me almost three hours to image a pack with PDP11GUI over my DL11, and I have a very limited set of packs with which to work (others on this list have graciously offered to help there; I need to send y'all some shipping boxes!)


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