Structuring basic programs for managing overlays in a small computer system

Abstract

In a small computer system, it is not unusual to write a BASIC program which is too large to fit into main memory. Such a program must be replaced by a collection of overlay modules together with inter-module sequencing logic. A sophisticated BASIC interpreter allows this sequencing to be done under program control. Unless carefully managed, a decomposition can produce an environment where programs exhibit undesirable characteristics. A structuring and design strategy is presented, discussed, and illustrated by a typical business application. Attention is given to program production, efficiency, reliability, maintainability, and modifiability using this strategy.