Three criteria for designing computing systems to facilitate debugging

Abstract

The designer of a computing system should adopt explicit criteria for accepting or rejecting proposed system features. Three possible criteria of this kind are input recordabillty, input specifiability, and asychronous reproducibility of output. These criteria imply that a user can, if he desires, either know or control all of the influences affecting the content and extent of his computer's output. To define the scope of the criteria, the notion of an abstract machine of a programming language and the notion of a virtual computer are explained. Examples of applications of the criteria concern the reading of a time-of-day clock, the assignment of capability indices, and memory reading protection in multiprogrammed systems.