LIST PROCESSOR LIPQ.

A list processor LIPQ upward compatible with LISP in principle but more suitable for short memory environment is designed and implemented on PDP-11 as a host language for an AI system. Quaternary cell is introduced other than binary cell of LISP to enhance the memory efficiency and the data accessibility, and a method of explicit use of backing store, not virtual memory technique, is devised to overcome the memory space limitations at the negligible cost of run time speed. For experimental purpose the state saving structure is perfectly open to the user so that he can freely choose his own control mechanism. LIPQ includes also powerful and comfortable I/O facilities to read and write a list of arbitrary structure and to print a list in a pretty format without concerning its context.