In no field has the mutual reinforcement of the development of device technology and system applications been more pronounced, wide spread or faster than in the area of computers. The rapid improvements in raw computational power available, cost-performance ratio, reliability, size and power consumption have all been remarkable in the recent past. Initially, computers could be visualized only as isolated stand-alone systems. Recent trends in minicomputers and microcomputers have however permitted them to be used as subsystems in larger systems and even as components in small subsystems and units.The availability of raw computational power and high information handling capabilities make large computers useful in such diverse applications as numerical weather prediction, management information systems and iiuclear research. The high reliability, speed and versatility of minicomputers are responsible for their being used increasingly in route switching and message switching applications in communications, on...