SEGMENT SIZES AND LIFETIMES IN ALGOL 60 PROGRAMS

AN EMPIRICAL STUDY WAS CONDUCTED ON THE NATURE OF THE MEMORY DEMANDS MADE BY A COLLECTION OF ALGOL 60 PROGRAMS. THE STUDY FOCUSED ON THE CHARACTERISTICS OF THE AMOUNT OF MEMORY REQUESTED AND THE HOLDING TIME. THE CONTOUR MODEL, WHICH INVOLVES A PROCESS DESCRIBED BY AN ALGORITHM AND A TIME ORDERED SEQUENCE OF RECORDS OF EXECUTIONS, WAS USED. THIRTY FOUR B5500 ALGOL 60 PROGRAMS WERE USED IN THE STUDY, WITH THE LARGEST HAVING A VIRTUAL MEMORY REQUIREMENT OF 162 WORDS. THE RESULTS SHOWED THAT THE MEDIAN LIFETIME FOR BLOCKS WAS BETWEEN 150 AND 200 MACHINE LANGUAGE INSTRUCTION EXECUTIONS. ALSO, THE MAJORITY OF ARRAY DECLARATIONS HAD NONDYNAMIC BOUNDS, WITH MOST BEING ALLOCATED ONCE. FINALLY, THE SHORT CONTOUR LIFETIMES AND THE SMALL MEDIAN SIZE OF THE CONTOUR DATA SEGMENTS INDICATE THAT A STACK IMPLEMENTATION OF THE ALGOL 60 PROCEDURE CALLS IS DESIRABLE. CHARTS. DIAGRAM.