I remember using a RSTS system that was installed at a high school in Milford NH circa 1980. DEC, being based in Massachusetts, donated countless minicomputers to schools, museums and other institutions around New England.
They also were planning to build a new factory off a new highway offramp a mile from my house that had been opened in 1980 but never built the factory because the computer industry left them behind.
Back in the day PDP-11s had lots of choices - RSTS was sort of the 'commercial' option - RSX was more the uni time sharing option and RT-11 was for the standalone tiny real-time embedded sorts of systems.
Fun fact: RSTS was originally named BTSS - Basic Time Sharing System. This was short lived since Honeywell had a product with the same name, so it was renamed to RTSS - Resource Time Sharing System. But due to a typing mistake that stuck it became RSTS - Resource Sharing Time-sharing System.
I took a computer programming class in college, circa 1976. PL/1 using the PL/C compiler. Punch cards, keypunch machines, greenbar paper, onery operators, contempt for first-time users, the whole bit. Wasn't that difficult actually, but the so-called "big iron" culture was more than off-putting.
Never took another programming class in college after that. Dug Stats instead.
Got a job teaching at a high school that had a PDP-11/34 running RSTS/E. Asked for a key to the lab and sat down with the manuals.
It was quiet, deliberate, personal and non-judgemental. No distractions, just the din of the cooling fans and the air-conditioning.
Hours and hours iterating through failed and successful BASIC programs. Just to see if I could.
The whole thing 'til now is a celebration of human intelligence.
They also were planning to build a new factory off a new highway offramp a mile from my house that had been opened in 1980 but never built the factory because the computer industry left them behind.