“The CONS was the first Lisp Machine produced at MIT (development started in 1973 with the first prototype available in 1976) and was designed by hackers for hackers. The CONS was superceded by an improved version in 1978 called the CADR. There were only about 25 CADRs produced by MIT, but the CADR was the basis for the first commercial LispM's that were produced by both LMI and Symbolics (both of which were created/staffed by ex-MIT hackers). Although a lot of the top MIT Lisp hackers left MIT to work for the commercial LispM manufacturers, Richard Stallman stayed on at MIT and, for several years, reproduced a lot of the commercial innovations on the MIT LispMs . Therefore, even though MIT's LispM will not have all the features of the later commercial LispM's, it is still a fabulous development environment. In fact, it is the basis for what is probably the most hacker-friendly development environment ever produced.” – Bill Clemenson