Postdoc
After he earned a PhD, he continued to work on AI projects for McCarthy, although his thesis advisor was Terry Winograd. He eventually began working for Lawrence Livermore National Labs, where he recruited a number of the researchers and programmers for a company he founded in 1984 (and would leave in 1992), and would survive until 1994, Lucid, Incorporated.
Gabriel was at various times the President and Chairman of Lucid Inc. The product the company shipped was an integrated Lisp IDE for Sun Microsystems’ RISC hardware architecture. This sidestepped the principal failure of Lisp machines by, in essence, rewriting the Lisp machine IDE for use on a more cost-effective and less moribund architecture. During this time period, Gabriel married his second wife, and had a daughter; he later divorced his second wife in 1993.
Eventually Lucid's focus shifted (during the AI Winter) to an IDE for C++. A core component of the IDE was Richard Stallman’s version of Emacs, GNU Emacs. GNU Emacs was not up to Lucid’s needs, however, and several Lucid programmers were assigned to help develop GNU Emacs. Friction arose between the programmers and Stallman over how to handle GUI issues, and Lucid forked; thus they were primarily responsible for the birth of what would come to be called XEmacs. One of his hires was another notable programmer, Jamie W. Zawinski.
Read more about this topic: Richard P. Gabriel, Biography