COMPUTER SYSTEM AND ITS WORKING
Computer Definition: A Computer is an electronic device that converts data into information. The computer accepts input in the form of data from users, processes it based on programming instructions, and then provides the Output in the desired format is known as information. The word computer has been derived from the word "compute" which means "to calculate". The first computers were used primarily for numerical calculations but today computer is a data processing machines because more than 80% of work done by computers is processing data. Data can be numerical or non-numerical or a combination of both likes marks of students, and employee details (name, address, age, designation, etc.).
Modern computers are electronic devices that are used for a variety of purposes ranging from browsing the web, writing documents, editing videos, creating software, playing video games, etc. The computer represents numbers, texts, and pictures through a string of binary digits. The computer is a very fast and accurate device. It can perform millions of calculations in a second. Charles Babbage is known as the father of computers who developed the first calculating machine in 1830. It was a mechanical computer(Analytical engine) that used punch cards as input. The first general-purpose electronic computer was ENIAC (Electronic Numerical Integrator and Computer) built in 1946 at the University of Pennsylvania, USA by John Mauchly and Presper Eckert.
A computer is often referred to as a data processing machine because it can store, process, and retrieve data whenever desired by the user. The processing of data includes performing many types of operations on data like arithmetic operations, logical operations,comparison operations, arranged in ascending or descending order, printing of data files, etc.
A general-purpose computer performs four main functions namely: it accepts data or instructions by way of input, process input or data, store the data or results and display the desired output. It has the
following four main components:
(1) Input Unit: This unit accepts data as input and converts it into computer-readable form. The input entered may be in the form of text, image, graphics, sound, video, etc. Input devices such as keyboard, mouse, scanner, etc are used to provide input.
2) Central Processing Unit: Central Processing Unit or CPU is also called the brain of the computer. It controls all input, processing, and output activities. It is also known as the processor. It performs arithmetic, logical, and controlling functions. CPU has the following two main sub-units:
(a) Arithmetic Logic Unit (ALU): This unit performs arithmetic and logical operations like add, subtract, multiply, divide, AND, OR, NOT, etc.
(b) Control Unit : This subunit is responsible for coordinating various operations using timing signals. It controls the flow of data from and to all parts of the computer. It is the supervisory system of the computer as it provides necessary control signals and is run by the computer's main clock.
(3) Storage Unit (Memory): A memory Unit is used to store data and information in a computer. The memory in a computer system is subdivided in two ways namely: Primary and Secondary Memory. The memory with which the processor can directly interact i.e. processor cache, RAM, and ROM is called primary memory whereas secondary memory is a term used for other storage devices like hard disk drives, flash drives, etc. mainly used for bulk storage.
(4) Output Unit: This unit provides the processed data in the desired form as ourput. The output may be text, sound, image, etc, Output devices such as Monitors, printers, speakers, plotters, etc. are used to provide output.
Fig. 1.1. Block Diagram of Computer
COMPUTER MCQS
