ABSTRACT
This chapter examines the question of how a program performs a computation, by giving an overview of the structure of the computer system. It also examines how a high-level source program is executed. The truth of the matter is that computers are indeed magical, in the sense that they can do amazing things. Computer organization is the study of the implementation of a computer. Computer architecture studies the structure presented to a program that can be used to perform a computation. Computers are made up of many separate devices. To understand how a computer performs a computation, probably the most interesting device to examine is the central processing unit, which is often simply called the processor. A processor typically has a set of general-purpose registers available to the programmer, and they are often numbered. Technically, the processor is only making it appear that it is running several programs simultaneously.
