Because of changes in computer technology and terminology, it is often difficult for present-day observers to judge the significance of early digital computer projects. This article follows some architectural themes of interest, as they evolved in the design of three innovative Manchester University computers: the Mark I, Atlas, and MU5. It traces themes such as operand address generation, instruction formats, and memory management during the period from 1948 to 1975. These themes are illustrated by a set of normalized diagrams that may aid further study of the original references.he purpose of this review is to explain in modern termi-T nology the structure of the principal digital computer designs to emerge from Manchester University in the period from 10% h180/Y1/0700 004$03 00 i 1993 IEEE