Reviving a VAX-11/750

Mattis Lind mattislind at
Tue Jun 16 02:59:27 CDT 2015

In my efforts to understand the problem with the Cache/TB Diagnostics I
tried to run it under 11/750 simulator in SimH. It fails too!

ECKAL -- VAX 11/750 Cache/TB Diagnostic
HALT instruction, PC: 00002608 (MTPR #F,#26)

Although not the same location.

On the real machine:

@?ECKAL -- VAX 11/750 Cache/TB Diagnostic

00003488  06

Trying to disassemble at 3488 in SimH gives me:

EXTZV @-1D(R7),#0,#0,(R8)+

The EXTZV is supposed be "Extract Zero-Extended Field"

I have never done any VAX-11 assembly coding so this is very new ground for
me... As far as I understand the diagnostic starts at address 200. But then
understanding what it does without the listing... Well. A long journey for


2015-06-15 22:07 GMT+02:00 Mark J. Blair <nf6x at>:

> > On Jun 15, 2015, at 11:59 , tony duell <ard at> wrote:
> >
> >
> >> I also may dump the console firmware PROMs at some point. I've already
> done some preliminary
> >> disassembly of the TU58 firmware.
> >
> > I am pretty sure I dumped all the PROMs and PALs in the CPU of my 11/730
> (but not the ones in the
> > R80) long before there was a bitsavers. I can see if I can find the
> dumps. What I don't have is the
> > Remote Diagnostic ROMs (this was another pair of 2K*4 ROMs that plug
> into sockets on the WCS
> > board and which run on the 8085). So no dumps of that.
> I have three WCS cards, including the one in my machine, but none of them
> have the remote diagnostic option.
> --
> Mark J. Blair, NF6X <nf6x at>

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