M9301-YB ROM flaky

Noel Chiappa jnc at mercury.lcs.mit.edu
Tue Jul 4 10:34:47 CDT 2017

    > From: Fritz Mueller

    > A question for Noel if he's listening here

You rang? :-)

    > how did you obtain your YB listing

I plugged one in, and ran a small program that dumped the contents to the
serial port.

    > would you consider it reliable?

Reasonably. If there was bit-rot in the board, I would not be able to tell,
and I only have one, so I can't compare. And I suppose I should have done the
dump twice, and compared the results, to make sure there wasn't an error
across the serial line.

    > I see a few words with different values than the ones that Noel has
    > listed in his partial M9301-YB disassembly.

Any chance you could send in some of the differences? I can take a look at
further disassembly, to see if the old values look reasonable (and if the new
ones are clearly confused).

    > would you think it reasonable to try blowing some replacement PROMs
    > based on that listing?

Once we've done the preceding steps, yes. (Since I already have the
more-or-less fully disassembled -YA code, doing the -YB should not be
_too_ hard; they seem to have pretty much the same functionality.)

    > I have seen no other source for the YB contents online anywhere else.

Ah. I was going to ask if there was source somewhere; even if it's only
hardcopy, we can still check.

    > Anybody have any particular part recommends for the PROMs?

The Engineering Drawings have a table of info.

    > I haven't been able to find engineering drawings for the M9301 online
    > so far

As Mattis says, they are in the 11/04 drawings (MP00019). But I'm a bit
puzzled why you didn't find them online; I have a page, "'Missing' Digital
Equipment Corporation Field Maintenance Print Sets Online":


specifically to deal with this, and indeed a search for "M9301 Field
Maintenance Print Set" and "M9301 Engineering Drawings" turns up this page as
the first entry for both searches?

    > I may also have a go at writing a program I can toggle in to read the
    > contents of my failing M9301 and dump them out over the console serial
    > to enable a systematic comparison

Let me find the one I wrote, and upload it.


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