[Simh] Is it possible to simulate the first Vaxen I ever used?

[Clem Cole]

On Mon, Mar 23, 2020 at 3:57 PM Johnny Billquist <bqt at softjar.se> wrote:

> The VAX-11/750 used 2901 though...
>
750 was made out of custom CMOS gate arrays.  The main adder was analyzed
as part of my thesis [long story - not for here, but a very clever
circuit.  I would later get to know the guy that did it].     Paul Gilbeau
and Dick Monroe were the main microcoders on the 750.  I'm pretty sure that
Paul was also one of the 780 microcode folks.   Very interesting guy. I
used to say he had a worm's eye view of the world -- perfect for his job as
lead microcoder; but trying to get up a level could be difficult.  I've
lost track of them both, although I still talk to Dave Cane a couple of
times a year and I think he knows how to find most of the HW team.

I'm fairly sure that the 750 used te BLISS based Micro2 tools as Tim
suggested and as I said, we cloned them at Masscomp in C (which later it
went west). Tim, you tell me, I thought the Masscomp version got sent to
the Jupiter team, but I'm pretty sure it was used for Prism.  I remember us
getting a 'bug report' because VAX-11/C didn't like something BSD's yacc
had generated at one of the Hatfield/McCoy parties. I remember changing
what it was and email it the next day.

FWIW:   All of the Masscomp FP/AP and the DACP used that set of microcode
tools since they were all AMD 29xx based.   IIRC, Chuck Palmer overhauled
the original hack we did for Paul and Dick because a few Masscomp customers
wanted to write custom DACP microcode and originally it was not too easy.
 I probably have a manual for that still around and maybe even the tools. But,
since I don't have a DACP on the MC500 I still have,  I never bother
scooping up the tools.

Also, I know that there was an Intel 808x processor (85 I think) that
shipped in the 750, but it was not an FEP.  It was limited to running the
cartridge tape controller.  I don't remember how the console serial port
was done (the 780 it was part of the FEP).  The 750 microcode did the boot
as someone else pointed out.  I've forgotten how the microcode was loaded
on a cold start.   I thought there was something in a ROM/EPROM, but I've
forgotten.  I do know the cartridge tape unit was needed to update the
microcode and that was the only way to do it.  But I don't remember you
need to have the tape on a cold reboot the like floppies on a 780, but I
could have forgotten.
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