Conversation so far:
When did Richard Stallman attend Harvard?
Richard Stallman was a first-year student at Harvard University in fall 1970.
What did Richard study at Harvard?
Stallman received a bachelor's degree in physics (magna cum laude) from Harvard in 1974.
Did Richard Stallman do any research at Harvard?
Did anything notable happen with Richard Stallman at Harvard?
In 1971, near the end of his first year at Harvard, he became a programmer at the MIT Artificial Intelligence Laboratory, and became a regular in the hacker community.
When did Richard Stallman enroll to MIT?
What did Richard Stallman study at MIT?
Richard Stallman pursued a doctorate in physics
When did Richard Stallman graduate from MIT?
Richard Stallman pursued a doctorate in physics for one year, but left that program to focus on his programming at the MIT AI Laboratory.
Did anything else interesting happen with Richard Stallman at MIT?
While as a research assistant at MIT under Gerry Sussman, Stallman published a paper (with Sussman) in 1977 on AI truth maintenance system, called dependency-directed backtracking.

Question: did he work anywhere else?
Self-contained rewrite: Did Richard Stallman work anywhere else while at MIT?