[TUHS] Research PBX legacy

[Doug McIlroy]

Prologue to TPC. Bob Morris did a visiting-researcher stint at
AT&T, where he became aware of infelicitous software architure
proposed for ESS 5. He thought Research could do it better. Ken,
Joe, and Lee bit. Lee's architecture was indeed novel: every
device in the system, right down to each touch-tone button, was
modeled as a process.  Only after the clean model was working
were some processes--notably the buttons--jammed together to
cinch in the process table.


The team got the switch working in a matter of months--in time
to demonstrate it to Indian Hill before ESS was irrevocably
set in stone. ESS architecture was indeed rethought, taking
some ideas from TPC.

TPC was named after "TPC, The Phone Company" in the 1967 film,
"The President's Analyst".

Doug