INTRODUCTION TO MICROPROCESSOR SYSTEM HARDWARE

A computer is made up of four basic functional units: the central processing unit (CPU),  memory, input, and output (I/O). The central processing unit does the actual computing  and is composed of two subparts: the arithmetic logic unit and control sections  Figure 2. The arithmetic logic unit (ALU) performs the actual numerical and logic  calculations such as addition, subtraction, AND, OR, and so on. The control section of
the CPU manages the data flow, such as reading and executing the program instructions.  If data require calculations, the control section hands it over to the ALU for processing.  In a microprocessor-based computer, the microprocessor is the CPU.