[Simh] Photorealistic panel for PDP-11/20

[Bob Eager]

On Sun, 1 May 2016 12:27:06 +0200
Jörg Hoppe <j_hoppe at t-online.de> wrote:

> Bob,
> 
> > On Sat, 30 Apr 2016 21:03:35 +0200
> > Jörg Hoppe <j_hoppe at t-online.de> wrote:
> >
> >> The header line says it all: another panel for BlinkenBone is
> >> there, the classic PDP-11/20.
> >> In function and style it fills the gap between the PDP-8 and the
> >> later PDP-11's.
> >>
> >> The GitHub distribution starts the 1970 Paper-tape BASIC, download
> >> here: https://github.com/j-hoppe/BlinkenBone/releases
> >>
> >> For info see
> >> http://retrocmp.com/projects/blinkenbone/simulated-panels/253-blinkenbone-simulated-pdp-11-20-panel
> >> and next page.
> >
> > Thank you! That was the first PDP-11 I ever used (and programmed in
> > MACRO-11).
> >
> > I ran DOS/BATCH and also RT-11. And I also ran a UNIX system on it.
> Do you remember which UNIX?
> I always considered the 11/20 to be too weak for that (no MMU,
> despite 18 ADDRESS switches&lamps). Or am I wrong?

Pretty weak, but OK for one person. This was Mini-UNIX. Main
differences: only one process in memory at the same time, simulated
pipes, no groups. This was circa 1977 I guess. I still have the manual
somewhere.

The way it worked was that the kernel lives in the bottom 16kW, and
processes were all linked to a base of 16kW.