Lisp Machines
Lisp Machines (commonly written 'LispM' and pronounced 'lispum' or 'lispem') are the nirvana (with all that implies ^_~) of Lisp users. A Lisp machine is a computer which runs an operating system and system software written entirely in Lisp, and which may have special hardware support for common Lisp operations (eg, GC, CONS).

The first official Lisp Machines were implemented at the MIT Artificial Intelligence Laboratory back in 1975 or so. The prototype machine was called the CONS, for obvious reasons. Its successor, the CADR (the 'next one') was a 48-bit general microcode processor which ran a 16-bit macrocode that implemented the lispm instruction set. An HTML version of the paper on the CADR, MIT A.I. Memo 528 is available online at Lambda Unlimited (a PDF version also exists). The only bug in this paper is that it is missing page 18, which I (James A. Crippen) hope to fix as soon as my hardcopy arrives from MIT. Or not. It turns out the hardcopy is missing page 18 too!

Many attempts have been made to implement a Lisp-based operating system for modern computers (eg the ubiquitous PC), but so far none of them have been successful. In order to avoid reimplementing the entire Lisp operating system (which is over 60 MB of source code) some intrepid hackers have embarked on an attempt to emulate a Lisp machine, the TI Explorer. The Explorer III ('E3') Project has made some progress, and work is currently underway on implementing the function calling macrocode instructions.

The other major player in the LispM market aside from TI was Symbolics; see, home of the Symbolics Museum and the 'Usual Suspects'. From their website: " is a community of people who used to work at Symbolics that have come together to share information, resources, experiences, humor, etc. Some of us put in a lot of years of our lives at Symbolics trying to create something new and better. Along the way, we made a lot of friends. The friendships and the memories have proven to be more enduring than the product. The network of personal friendships and contacts persists today, in some cases more than 20 years after the fact."

A very useful book for learning more about the Symbolics Lisp Machine is "Lisp Lore: A Guide to Programming the Lisp Machine. Second Edition. Hank Bromley and Richard Lamson". It is very expensive - but interestingly it is still being sold. The book was itself written with the Concordia publishing system on the Lisp Machine.


  1. Introduction
  2. Getting Started on the Lisp Machine
  3. Flow of Control
  4. More on Navigating the Lisp Machine
  5. What's a Flavor
  6. User Interface
  7. The Graph Example
  8. Streams and Files
  9. The Calculator Example
  10. Systems, Storage and Errors
  11. The Card Game Example
  12. More Advanced Use of the Editor
  13. A Quick Look at the Network
  14. Appendix A: Basic Zmacs Commands

NB: Right now there are several second-hand copies of this book available through

MF: Lisp lore can be found at for free!

Lisp History