Computers architecture is concerned with the structure and behavior of digital computers. It has developed into a discipline for the design and evaluation of computers largely in response to the proliferation of these machines over the last couple of decades. This proliferation has, in turn, been driven by advances in computer technology, both hardware and software. In particular, the development of very large scale integration (VLSI) has had a profound influence in lowering the cost and improving the performance of all types of computers. Recent developments such as VLSI-based personal computers and relatively low-cost supercomputers have allowed computers to be used in many new applications. Consequently, the concepts of computer architecture and organization have become increasingly relevant to a large number of scientists, engineers, and other professionals.