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INTRODUCTION A COMPUTER is an electronic device that can be instructed to carry out an arbitrary set of arithmetic or logical operations automatically. Characteristics of Computers Speed: The speed of computation is very high as the signals pass at the speed of light. Thus, millions of calculations can be done in a second. Accuracy: As computers work on inbuilt software programs, there is no scope for human errors and are hence, highly accurate. Information and Storage: A computer can store a large amount of data or instructions in its memory which can be retrieved at point of time. Other characteristics include: Consistency, Automatic Operation, and Flexibility. History of Computers Father of Computer: Charles Babbage Father of Modern Computer Science: Alan Tuning First Un-programmable Electronic Digital Computer: Atanas off Berry Computer (ABC) First Purpose Electronic Digital Computer: Electronic Numerical Integrator and Calculator (ENIAC) GENERATIONS OF COMPUTERS: First Generation (1946 - 1959) Used vacuum tubes & batch processing OS Machine & Assembly Languages used Examples: ENIAC, EDVAC, UNIVAC, IBM-701, IBM-650 Second Generation (1959-1965) Used transistors OS: Multi-Bag remaining, Time sharing Memory: Magnetic cores, magnetic tapes and disks Used assembly and high-level languages like FORTRAN, COBOL, Algol Examples: IBM 1620, IBM 7094, CDC 1604 Third Generation (1965-1971) Used ICs OS: Remote processing, Time-sharing, Real-time, Multi-programming Used High-level languages FORTRAN-II TO IV, COBOL, PASCAL PL/1, BASIC, ALGOL-68 Examples: IBM-360 series, Honeywell-6000 series, PDP, IBM-370/1683 Fourth Generation (1971-1980) VLSI Circuits Used Memory: Semiconductor and Winchester disk High level Languages: Fortan 77, Pascal, Cobol used REKIB AFREDI 2 Visit:www.rekibafredi.com
Examples: DEC 10, STAR 1000, PDP 11, Super Computers (CRAY-1, CRAY-X- MP) The present generation of computers is the Fifth Generation of computers, i.e. 1980-till date. The computers use ultra large scale integration (ULSI). High level languages like C++, Java, NET, etc. are used. Some examples are: laptop, desktop, ultrabook etc. TYPES OF COMPUTERS 1. Personal Computers: Small, inexpensive computer for personal use Also called a micro-computers Popularly used at homes for playing games and/ or surfing the Internet. Used for word processing, desktop publishing, spreadsheet and database management applications 2. Mini Computers These were designed for specific tasks but have now lost popularity due to the advent of Pcs. 3. Mainframes These are expensive and large sized computers Are capable of supporting hundreds of users simultaneously Used for specific large scale applications 4. Super Computers Powerful, expensive and the fastest computers Used for applications that require large amounts of mathematical computations For example: weather forecasting, fluid dynamics, graphic design etc. COMPUTER FUNDAMENTALS A computer system has four basic components. Parts of a Computer System Hardware: represents the physical and tangible components of the computer (keyboard, mouse, monitor etc.). Software: is a set of electronic instructions called programs that make the computer perform tasks. Data: the raw facts, which the computer stores and reads in the form of numbers. Users: the people who make use of a computer to obtain certain results/ outcomes. REKIB AFREDI 3 Visit:www.rekibafredi.com
DATA PROCESSING CYCLE OF A COMPUTER A computer's data processing cycle comprises of the following three steps: 1. Input: It refers to the commands given by a user to the computer using input devices like mouse, keyboard etc. 2. Processing: In this step, the command given by the user are carried out by the computer. Thus, this step produces a more useful form of data at the end. 3.Output: The result of the processing that is stored and displayed to the user by means of output devices like monitor, printer etc. is called output. REKIB AFREDI 4 Visit:www.rekibafredi.com