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

[Ethan Dicks]

On Sun, Mar 22, 2020 at 8:21 PM Dan Gahlinger <dgahling at hotmail.com> wrote:
> I believe it was a Vax 730 with a PDP-8 FEP, inside the main chassis it actually had a part labelled (in big letters) "FUBAR"
>
> If I remember correctly, it ran VMS v2.4

I'm pretty sure VMS 3.0 was the first to support the 11/730 (the
11/730 came out in April, 1982 and VMS 3.0 release notes are dated
May, 1982, and mentions that the upgrade scripts do not work with the
11/730 - you have to follow the install procedure).

I _think_  VMS 2.3 and the 11/750 are contemporary.  There is
definitely an install guide for VMS 2.3 on the 11/750.  I don't recall
if you could load VMS 2.2 on a 11/750 or not.  What is clear is that
VMS 2.0 is documented in the release notes that the SID register has
to have a CPU type of '1' and a min ECO of '3' (the 11/750 is a CPU
type '2').

Using a PDP-8 as an FEP on any VAX definitely sounds odd.  The 11/780
(and 11/782 and 11/785) used a PDP-11 as the FEP.   The console medium
was the RX01.  The 11/750 has an embedded console processor; I'm not
quite sure how they implemented it (11/750 microcode?)  The 11/730 has
an 8085 that you talk to first that reads files off a console TU58 and
pokes shared resources on the VAX processor (much more like an 11/780
than the 11/750).  The differences made life in the 80s festive for a
new System Manager learning how they worked.

> Note: someone decades ago told me the plural for Vax was "Vaxen", and it just stuck...

Yep.  That's normal usage.

Cheers,

-ethan