The Distinguished Dissertation series is published on behalf of the Conference of Professors and Heads of Computing and the British Computer Society, who annually select the best British PhD dissertations in computer science for publication. The dissertations are selected on behalf of the CPHC by a panel of eight academics. Each dissertation chosen makes a noteworthy contribution to the subject and reaches a high standard of exposition, placing all results clearly in the context of computer science as a whole. In this way computer scientists with significantly different interests are able to grasp the essentials - or even find a means of entry - to an unfamiliar research topic. This is the first book in the area of Hardware Evolution. It uses a series of experiments to explore the practicalities of removing the constraints on circuit structure and dynamics which are normally needed to permit design abstractions, culminating in a simple but non-trivial application.