The story
The IEEE Computer Society traces its origins to the Subcommittee on Large-Scale Computing, established in 1946 by the American Institute of Electrical Engineers (AIEE), and to the Professional Group on Electronic Computers (PGEC), established in 1951 by the Institute of Radio Engineers (IRE). When the AIEE merged with the IRE in 1963 to form the Institute of Electrical and Electronics Engineers (IEEE), these two committees became the IEEE Computer Group. The group established its own constitution and bylaws in 1971 to become the IEEE Computer Society.
From Wikipedia’s article on IEEE Computer Society, shared under CC BY-SA 4.0.4
