[TUHS] Recreation of the PDP-7 UNIX TMG compiler compiler

[Phil Budne <phil@ultimate.com>]

I was a member of the team that typed in scans of PDP-7 UNIX (the
first batch of scans done didn't include the shell, so I cobbled one
together in March of 2016).

Scans of a second batch of listings turned up and were entered two
years ago (October 2019), including the original shell, and appeared
to be part of Doug McIlroy's implementation of TMG (TransMoGrifier),
the compiler compiler first used to implement B.

In January 2020 we got confirmation that the files t1.s thru t8.s
were, in fact, for TMG, but that we were missing the compiler for the
TMGL language, written in TMGL and the generated code.

In what is perhaps best described as a crazed act, over the past two
months I've worked to recreate a working TMG environment on PDP-7
UNIX, including a B compiler in TMGL, currently available at:

https://github.com/philbudne/pdp7-unix/tree/tmg

A good starting place is
https://github.com/philbudne/pdp7-unix/blob/tmg/misc/tmg-notes.txt
which started as my collected notes, questions and findings, and I've
expanded it with prose, observations and thoughts that could, at least
conceivably, be of interest to those not as oriented towards
self-punishment as I am.

(and on that topic, if you're looking for someone to expand, contract,
or otherwise deal with some seemingly intractable legacy code, let me
know: http://www.regressive.org/phil/resume.html)