Microprcessor Bsc CSIT Sem second

>Introduction

Chapter – 1

Introduction

A Microprocessor is a multipurpose programmable, clock driven, register based electronic device that reads binary instructions from a storage device called memory, accepts binary data as input, processes data according to those instructions and provide result s as output. The microprocessor operates in binary 0 and 1 known as bits are represented in terms of electrical voltages in the machine that means 0 represents low voltage level and 1 represents high voltage level. Each microprocessor recognizes and processes a group of bits called the word and microprocessors are classified according to their word length such as 8 bits microprocessor with 8 bit word and 32 bit microprocessor with 32 bit word etc.

Fig 1.1: A Programmable Machine

Terms used

     ·         CPU: - Central processing unit which consists of ALU and control unit.
     ·         Microprocessor: - Single chip containing all units of CPU.
     ·         Microcomputer: - Computer having microprocessor as CPU.
     ·         Microcontroller: single chip consisting of MPU, memory, I/O and interfacing circuits.
     ·         MPU: - Microprocessing unit – complete processing unit with the necessary control signals.

     Basic Block Diagram of a Computer

Traditionally, the computer is represented with four components such as memory, input, output and central processing unit (CPU) which consists of arithmetic logic unit (ALU) and control unit (CU).

 

 

Fig 1.2 (a): Traditional Block diagram of a computer

 

The CPU contains various registers to store data, the ALU to perform arithmetic and logical operations, instruction decoders, counters and control lines.

The CPU reads instructions from memory and performs the tasks specified. It communicates with input/output (I/O) devices either to accept or to send data, the I/O devices is known as peripherals.

Later on around late 1960’s, traditional block diagram can be replaced with computer having microprocessor as CPU which is known as microcomputer. Here CPU was designed using integrated circuit technology (IC’s) which provided the possibility to build the CPU on a single chip.

Fig 1.2 (b): Block Diagram of a computer with the Microprocessor as CPU

 

Later on semiconductor fabrication technology became more advanced, manufacturers were able to place not only MPU but also memory and I/O interfacing circuits on a single chip known as microcontroller, which also includes additional devices such as A/D converter, serial I/O, timer etc.

 

Fig 1.2 (c): Block Diagram of a Microcontroller

 

     Organization of a microprocessor based system

Microprocessor based system includes there components microprocessor, input/output and memory (read only and read/write). These components are organized around a common communication path called a bus.

Fig 1.3: Microprocessor Based System with Bus Architecture

 

Microprocessor:

 

It is clock driven semiconductor device consisting of electronic logic circuits manufactured by using either a large scale integration (LSI) or very large scale integration (VLSI) technique. It is capable of performing various computing functions and making decisions to change the sequence of program execution. It can be divided in to three segments.

A.      Arithmetic/Logic unit: It performs arithmetic operations as addition and subtraction and logic operations as AND, OR & XOR.
B.      Register Array: The registers are primarily used to store data temporarily during the execution of a program and are accessible to the user through instruction. The registers can be identified by letters such as B, C, D, E, H and L.
C.      Control Unit: It provides the necessary timing and control signals to all the operations in the microcomputer. It controls the flow of data between the microprocessor and memory & peripherals.

Setting the Viewport

This example does not really do anything, other than showing you how to add the viewport meta element.