New LISP Techniques for a Paging Environment

Abstract

The system described herein employs the block concept, and that of global and local variables, in addition to the methods applied in most LISP systems. Also, a new means of list representation is used: “local sequential” for lists created during compilation, and “block level sequential” for those created dynamically. A new garbage collection algorithm has been introduced to make lists as compact as possible; partial garbage collection is performed after each block exit instead of total garbage collection when storage is exhausted. The algorithm does not use the customary flagging procedure. This combination of features has eliminated the need for a free list, and effectively minimizes the number of pages used at any moment. © 1971, ACM. All rights reserved.