[Simh] Burroughs B5500 simulator.

[Nigel Williams]

This is excellent Richard, glad to see such a complete B5500 emulation
on the SimH platform.

Here are additional notes related to Burroughs emulators and these
machines generally; I'm posting here in the hope someone might have
something relevant and as a placeholder for the current status of
recovery efforts for Burroughs machines.

B5500:
1. Sid McHarg has the oldest B5500 emulation we know of implemented in
C++ and can be run on Linux/OS X (Sid has shown it running on a
Raspberry PI too). Sid was responsible for preserving the set of
7-track MCP distribution tapes that we now all rely on for these B5500
emulators.

2. There was a Python-based emulator under development but we haven't
heard from the author for a while so not sure of its current status.
Mark Lloyd was well advanced with an emulator written in
Pascal/Lazarus on Linux. Having so many different implementations of
emulators for the B5500 has helped uncovering some quite subtle bugs
along the way.

3. Discussion about the retro-B5500 emulator and the B5500 happens via
this Google Group from time to time:

https://groups.google.com/forum/?hl=en#!forum/retro-b5500

4. There is quite a bit of B5500 software remaining to be proofed,
corrected and tested - some quite interesting items, for example Gary
Kildall's APL for the B5500. Another interesting piece of software is
the B6500 simulator that run on the B5500 that Burroughs was using to
support the implementation of this follow-on machine. This B6500
simulator package includes MCP 0.0. Note the B6500 simulator needs a
specially modified version of ALGOL; it is thought changes can be made
to the ALGOL compiler we have without too much effort.

B205:
5. Paul Kimpel has done another excellent implementation of a
browser-based B205 emulation (datatron.blogspot.com). This could be
used as the basis for a SimH implementation if someone was interested.
Paul Kimpel and Tom Sawyer have recovered several notable software
items from Donald Knuth such as his ALGOL-58 implementation.

B6700:
6. We're looking for software for the Burroughs B6700 (and related
family members, B7700, B6800). Dan Young from Unisys has helped us
locate a partial release of MCP 2.1 for the B6700, and we have a few
other pieces from different releases but at this stage no complete
release has been found.

7. Peter Grootswagers has done an amazing Java implementation of a
complete B6700 system (CPU + peripherals and cross-compilers) but like
us is somewhat stymied by the lack of software.

8. A few of us would like to implement a replica of the impressive
B6700 blinkenlights front-panel (MDL - Maintenance Diagnostics Logic
panel). We've tracked down the only known panel still in existence
(located in Denmark) and we have the start of a nice set of pictures
of various parts. At this stage an accurate graphical UI version of
the MDL could be easily implemented as standalone and later
incorporated into an emulation. We have a few seconds of video footage
of the MDL in operation here:

https://www.youtube.com/watch?v=lpv6pXlwEjY

We're waiting for better close-up detail of the MDL and also trying to
track down the original source of the MDL video footage.

9. I maintain a list of lists relating to B5000 and B6000/7000 systems here:

https://docs.google.com/spreadsheets/d/1JnMsyE8ssJi_-MUsK0rT9LPtNpeJCpTv1QrFw-917Y8/edit?usp=sharing

The lists aim to track the locations of installations, software,
versions etc. Corrections are very welcome.

Illiac IV:
10. A few of us are interested in the early supercomputer known as the
Illiac IV; Burroughs was responsible for much of the initial
implementation. As only one was ever built, it lacks the multiplier
effect to help preserve copies of the software. We've contacted about
a dozen people closely involved with this machine, but so far we are
not having any success finding any parts of the toolchain for this
system (the only new item found in the last couple of years is the CFD
manual). NASA Ames (where the Illiac IV ended up) has on-staff
historians who are supportive but have not found anything either (I do
wonder if the best option is for someone to visit every single office
at NASA Ames and ask all the residents if they have any tapes,
listings of other ephemera at the back of a drawer or filing cabinet).