Segment sizes and liftetimes in Algol 60 programs

The characteristics of the virtual memory requirements of a sample of Algol 60 programs have been measured. Distributions are presented for the sizes of memory requests and for their holding times (lifetimes). The results are presented in terms of Johnston's contour model and a simple abstract machine. They provide new empirical evidence of certain aspects of the construction and behavior of real programs, and some of their implications for the design of virtual memory systems are presented and discussed.