A multiprocessing system for the direct execution of LISP

ABSTRACT

Current implementations were found to be impractical for airborne use due to LISP's incompatability with conventional computer architectures. Direct execution of LISP with tasks distributed between three processors, seemed to be a workable solution. The language was analyzed, and a special token was devised, using a descriptor with a single pointer. Through careful distribution of responsibilities, control and data flow between the processors was minimized. Significant memory savings resulted from ASCII storage and real time garbage collection. A simulation was used to help estimate execution times and showed a factor of 50 to 100 increase in speed. Thus, through the direct execution of LISP by a multiprocessing system, Computer-Aided Decision-Making could be implimented to enhance the safety of flight operations.

REFERENCES

• 1: Chien, R.T., et al, "Computer-Aided Decision-Making for Flight Operations, Technical Report No. 2", Coordinated Science Laboratory Report T-18, University of Illinois, June 1975.
• 2: Douglas Wells Clark, List structure: measurements, algorithms, and encodings., 1976
• 3: Greenblatt, Richard, "The LISP Machine", Working Paper No. 79, MIT Artificial Intelligence Laboratory, November 1974.
• 4: Baker,Jr., Henry G., "List Processing in Real Time on a Serial Computer", Working Paper No. 139, MIT Artificial Intelligence Laboratory, February 1977.

INDEX TERMS

Primary Classification:
  C. Computer Systems Organization
  C.1 PROCESSOR ARCHITECTURES
      C.1.2 Multiple Data Stream Architectures (Multiprocessors)

Additional Classification:
  D. Software
  D.3 PROGRAMMING LANGUAGES
      D.3.2 Language Classifications

          Nouns: LISP

General Terms:
Design, Languages