Digital Electronics: Principles, Devices and Applications

13

Microprocessors

The microprocessor is the heart of a microcomputer system. In fact, it forms the central processing unit of any microcomputer and has been rightly referred to as the computer on a chip. This chapter gives an introduction to microprocessor fundamentals, followed by application-relevant information, such as salient features, pin configuration, internal architecture, instruction set, etc., of popular brands of eight-bit, 16-bit, 32-bit and 64-bit microprocessors from international giants like INTEL, MOTOROLA and ZILOG.

13.1 Introduction to Microprocessors

A microprocessor is a programmable device that accepts binary data from an input device, processes the data according to the instructions stored in the memory and provides results as output. In other words, the microprocessor executes the program stored in the memory and transfers data to and from the outside world through I/O ports. Any microprocessor-based system essentially comprises three parts, namely the microprocessor, the memory and peripheral I/O devices. The microprocessor is generally referred to as the heart of the system as it performs all the operations and also controls the rest of the system. The three parts are interconnected by the data bus, the address bus and the control bus (Fig. 13.1).

The memory stores the binary instructions and data for the microprocessor. The memory can be classified as the primary or main memory and secondary memory. Read/write memory (R/WM) and read only memory (ROM) ...