The Design of Colossus (foreword by Howard Campaigne)
Thomas H. Flowers · IEEE Annals of the History of Computing · 1983
This article describes the construction and operation of the Colossus machines. The machines had most if not all of the essential features of a modern computer, except that variable programming was provided not by memory store but by hard-wired function units selected and interconnected by switches operated by the mathematician-programmers.