The late B. Holdsworth was born in Leeds and after war service in the Royal Navy he was awarded the B.Sc.(Eng.) degree by London University, and later in 1964 was awarded the M.Sc. degree by the University of Birmingham. After working on Radar Development with the Marconi Company for a number of years he was appointed Senior Lecturer at the University of Science and Technology, Kumasi, Ghana. This appointment was followed by further university appointments in Nigeria and Zambia.On returning to the UK in 1968 he joined the staff of the University of London at Chelsea College where he held successively the appointments of Lecturer and Senior Lecturer until he retired in 1985. During this period he developed and ran a number of short courses on digital techniques designed for practising engineers. He was also invited by the International Telecommunications Union on a number of occasions to give a series of lecture courses on the Indian sub-continent. In addition to the present volume he has written a book entitled "Microprocessor Engineering and acted as editor for the "Digital Systems Reference Book. For the first ten years of his retirement he worked as a part-time visiting lecturer at King's College and University College, London University.R.C. Woods was born in Leicester, England, and was awarded the B.A. and M.A. degrees in Physics by New College, Oxford University. He then worked in the Clarendon Laboratory, Oxford University, on magnetic resonance in rare earth metal alloys, and was awarded the D.Phil. degree in 1980. Next followed a period as a Research Assistant in the Engineering Science Department at the University of Oxford, where he worked on surface-acoustic wave devices. From 1982 to 1983, he was Senior Scientist at Plessey Research (Caswell) Ltd., Towcester, specialising in semiconductor lasers and LED systems. He was then a Lecturer (and subsequently Senior Lecturer) in Electronic and Electrical Engineering at the University of Sheffield, and in 2001 he was appointed Full Professor of Electrical and Computer Engineering at Iowa State University, Ames, Iowa. He currently has research interests in magnetic recording, novel solid-state devices, and device modelling, and he has authored more than 70 refereed research publications in these fields. He has been in charge of courses on Digital Systems and Semiconductor Devices for many years.