Fundamentals of Computer By Dr Virender Khurana Associate

Fundamentals of Computer By Dr. Virender Khurana Associate Professor, Vaish (PG) College Rohtak

• Computer • Characteristic features of computers • Computers’ evolution to their present form • Computer generations • Characteristic features of each computer generation

COMPUTER • The word computer comes from the word “compute” , which means, “to calculate” • Thereby, a computer is an electronic device that can perform arithmetic operations at high speed • Computer is an electronic device which can accept data from outside world (Input), process it and gives us right/desired Output

Characteristics of Computers • 1) Automatic: Given a job, computer can work on it automatically without human interventions • 2) Speed: Computer can perform data processing jobs very fast, usually measured in microseconds (10 -6), nanoseconds (10 -9), and picoseconds (10 -12) • 3) Accuracy: Accuracy of a computer is consistently high and the degree of its accuracy depends upon its design. Computer errors caused due to incorrect input data or unreliable programs are often referred to as Garbage-In. Garbage-Out (GIGO)

• 4) Diligence: Computer is free from monotony, tiredness, and lack of concentration. It can continuously work for hours without creating any error and without grumbling • 5) Versatility: Computer is capable of performing almost any task, if the task can be reduced to a finite series of logical steps • 6) Power of Remembering: Computer can store and recall any amount of information because of its secondary storage capability. It forgets or looses certain information only when it is asked to do so

Disadvantages • 7) No I. Q. : A computer does only what it is programmed to do. It cannot take its own decision in this regard • 8) No Feelings: Computers are devoid of emotions. Their judgement is based on the instructions given to them in the form of programs that are written by us (human beings)

Evolution of Computers • Blaise Pascal invented the first mechanical adding machine in 1642 • Baron Gottfried Wilhelm von Leibniz invented the first calculator for multiplication in 1671 • Keyboard machines originated in the United States around 1880 • Around 1880, Herman Hollerith came up with the concept of punched cards that were extensively used as input media until late 1970 s

• Charles Babbage is considered to be the father of modern digital computers Ø He designed “Difference Engine” in 1822 Ø He designed a fully automatic analytical engine in 1842 for performing basic arithmetic functions Ø His efforts established a number of principles that are fundamental to the design of any digital computer § The Mark I Computer (1937 -44) § The Atanasoff-Berry Computer (1939 -42) § The ENIAC (1943 -46) § The EDVAC (1946 -52) § The EDSAC (1947 -49) § Manchester Mark I (1948) § The UNIVAC I (1951)

Computer Generations • “Generation” in computer talk is a step in technology. It provides a framework for the growth of computer industry • Originally it was used to distinguish between various hardware technologies, but now it has been extended to include both hardware and software • Till today, there are five computer generations

• Generation in computer terminology is a change in technology a computer is/was being used. Initially, the generation term was used to distinguish between varying hardware technologies. Nowadays, generation includes both hardware and software, which together make up an entire computer system. • There are five computer generations known till date. Each generation has been discussed in detail along with their time period and characteristics. In the following table, approximate dates against each generation has been mentioned, which are normally accepted.

First Generation (1946 -1959) • The computers of first generation used vacuum tubes as the basic components for memory and circuitry for CPU (Central Processing Unit). These tubes, like electric bulbs, produced a lot of heat and the installations used to fuse frequently. Therefore, they were very expensive and only large organizations were able to afford it. • In this generation, mainly batch processing operating system was used. Punch cards, paper tape, and magnetic tape was used as input and output devices. The computers in this generation used machine code as the programming language.

• The main features of the first generation are − * Vacuum tube technology * Unreliable * Supported machine language only * Very costly * Generated a lot of heat * Slow input and output devices * Huge size * Need of AC * Non-portable * Consumed a lot of electricity • Some computers of this generation were − ENIAC EDVAC UNIVAC IBM-701 IBM-650

Second Generation (1959 -1965) • In this generation, transistors were used that were cheaper, consumed less power, more compact in size, more reliable and faster than the first generation machines made of vacuum tubes. In this generation, magnetic cores were used as the primary memory and magnetic tape and magnetic disks as secondary storage devices. • In this generation, assembly language and high -level programming languages like FORTRAN, COBOL were used. The computers used batch processing and multiprogramming operating system.

• The main features of second generation are − Ø Reliable in comparison to first generation computers Ø Smaller size as compared to first generation computers Ø Generated less heat as compared to first generation computers Ø Consumed less electricity as compared to first generation computers Ø Faster than first generation computers Ø Still very costly AC required Ø Supported machine and assembly languages • Some computers of this generation were − IBM 1620 IBM 7094 CDC 1604 CDC 3600 UNIVAC 1108

Third Generation (1965 -1971) • The computers of third generation used Integrated Circuits (ICs) in place of transistors. A single IC has many transistors, resistors, and capacitors along with the associated circuitry. • The IC was invented by Jack Kilby. This development made computers smaller in size, reliable, and efficient. In this generation remote processing, time-sharing, multiprogramming operating system were used. High-level languages (FORTRAN-II TO IV, COBOL, PASCAL PL/1, BASIC, ALGOL-68 etc. ) were used during this generation.

• The main features of third generation are − Ø Ø Ø IC used More reliable in comparison to previous two generations Smaller size * Generated less heat * Faster Lesser maintenance * Costly * AC required Consumed lesser electricity Supported high-level language • Some computers of this generation were − • • • IBM-360 series Honeywell-6000 series PDP (Personal Data Processor) IBM-370/168 TDC-316

Fourth Generation (1971 -1980) • Computers of fourth generation used Very Large Scale Integrated (VLSI) circuits. VLSI circuits having about 5000 transistors and other circuit elements with their associated circuits on a single chip made it possible to have microcomputers of fourth generation. • Fourth generation computers became more powerful, compact, reliable, and affordable. As a result, it gave rise to Personal Computer (PC) revolution. In this generation, time sharing, real time networks, distributed operating system were used. All the high-level languages like C, C++, DBASE etc. , were used in this generation.

• The main features of fourth generation are − Ø Ø Ø Ø Ø VLSI technology used Very cheap Portable and reliable Use of PCs Very small size Pipeline processing No AC required Concept of internet was introduced Great developments in the fields of networks Computers became easily available • Some computers of this generation were − Ø Ø Ø DEC 10 STAR 1000 PDP 11 CRAY-1(Super Computer) CRAY-X-MP(Super Computer)

Fifth Generation (1980 onwards) • In the fifth generation, VLSI technology became ULSI (Ultra Large Scale Integration) technology, resulting in the production of microprocessor chips having ten million electronic components. • This generation is based on parallel processing hardware and AI (Artificial Intelligence) software. AI is an emerging branch in computer science, which interprets the means and method of making computers think like human beings. All the high-level languages like C and C++, Java, . Net etc. , are used in this generation.

• The main features of fifth generation are − Ø Ø Ø Ø ULSI technology Development of true artificial intelligence Development of Natural language processing Advancement in Parallel Processing Advancement in Superconductor technology More user-friendly interfaces with multimedia features Availability of very powerful and compact computers at cheaper rates • Some computer types of this generation are − Ø Ø Ø Desktop Laptop Note. Book Ultra. Book Chrome. Book

Computer Types • Computers can be broadly classified by their speed and computing power. • PC (Personal Computer) It is a single user computer system having moderately powerful microprocessor • Workstation It is also a single user computer system, similar to personal computer however has a more powerful microprocessor. • Mini Computer It is a multi-user computer system, capable of supporting hundreds of users simultaneously. • Main Frame It is a multi-user computer system, capable of supporting hundreds of users simultaneously. Software technology is different from minicomputer. • Supercomputer It is an extremely fast computer, which can execute hundreds of millions of instructions per second.

Personal Computer (PC) • A PC can be defined as a small, relatively inexpensive computer designed for an individual user. PCs are based on the microprocessor technology that enables manufacturers to put an entire CPU on one chip. Businesses use personal computers for word processing, accounting, desktop publishing, and for running spreadsheet and database management applications. At home, the most popular use for personal computers is playing games and surfing the Internet. • Although personal computers are designed as single-user systems, these systems are normally linked together to form a network. In terms of power, now-a-days high-end models of the Macintosh and PC offer the same computing power and graphics capability as low-end workstations by Sun Microsystems, Hewlett-Packard, and Dell.

Workstation • Workstation is a computer used for engineering applications (CAD/CAM), desktop publishing, software development, and other such types of applications which require a moderate amount of computing power and relatively high quality graphics capabilities. • Workstations generally come with a large, high-resolution graphics screen, large amount of RAM, inbuilt network support, and a graphical user interface. Most workstations also have mass storage device such as a disk drive, but a special type of workstation, called diskless workstation, comes without a disk drive. • Common operating systems for workstations are UNIX and Windows NT. Like PC, workstations are also single-user computers like PC but are typically linked together to form a local-area network, although they can also be used as standalone systems.

Minicomputer • It is a midsize multi-processing system capable of supporting up to 250 users simultaneously.

Mainframe • Mainframe is very large in size and is an expensive computer capable of supporting hundreds or even thousands of users simultaneously. Mainframe executes many programs concurrently and supports many simultaneous execution of programs.

Supercomputer • Supercomputers are one of the fastest computers currently available. Supercomputers are very expensive and are employed for specialized applications that require immense amount of mathematical calculations (number crunching). • For example, weather forecasting, scientific simulations, (animated) graphics, fluid dynamic calculations, nuclear energy research, electronic design, and analysis of geological data (e. g. in petrochemical prospecting).

• In this next section you will learn about: • Basic organization of a computer system • Basic operations performed by all types of computer systems • Input unit and its functions • Output unit and its functions • Storage unit and its functions • Types of storage used in a computer system

Basic Organization of a Computer System

The Five Basic Operations of a Computer System • Inputting The process of entering data and instructions into the computer system • Storing Saving data and instructions to make them readily available for initial or additional processing whenever required • Processing Performing arithmetic operations (add, subtract, multiply, divide, etc. ) or logical operations (comparisons like equal to, less than, greater than, etc. ) on data to convert them into useful information • Outputting The process of producing useful information or results for the user such as a printed report or visual display • Controlling Directing the manner and sequence in which all of the above operations are performed

Input Unit • An input unit of a computer system performs the following functions: • 1. It accepts (or reads) instructions and data from outside world • 2. It converts these instructions and data in computer acceptable form • 3. It supplies the converted instructions and data to the computer system for further processing

Output Unit • An output unit of a computer system performs the following functions: • 1. It accepts the results produced by the computer, which are in coded form and hence, cannot be easily understood by us • 2. It converts these coded results to human acceptable (readable) form • 3. It supplies the converted results to outside world

Central Processing Unit (CPU) • CPU is considered as the brain of the computer. CPU performs all types of data processing operations. It stores data, intermediate results, and instructions (program). It controls the operation of all parts of the computer. • CPU itself has the following three components Ø ALU (Arithmetic Logic Unit) Ø Memory Unit Ø Control Unit

Arithmetic Logic Unit (ALU) • Arithmetic Logic Unit of a computer system is the place where the actual executions of instructions takes place during processing operation Control Unit (CU) Control Unit of a computer system manages and coordinates the operations of all other Components of the computer system

Storage Unit • The storage unit of a computer system holds (or stores) the following : • 1. Data and instructions required for processing (received from input devices) • 2. Intermediate results of processing • 3. Final results of processing, before they are released to an output device

Two types of Storage • Primary storage Ø Used to hold running program instructions Ø Used to hold data, intermediate results, and results of ongoing processing of job(s) Ø Fast in operation Ø Small Capacity Ø Expensive Ø Volatile (looses data on power dissipation)

Two types of Storage • Secondary storage Ø Used to hold stored program instructions Ø Used to hold data and information of stored jobs Ø Slower than primary storage Ø Large Capacity Ø Lot cheaper that primary storage Ø Retains data even without power

The System Concept • A system has following three characteristics: 1. A system has more than one element 2. All elements of a system are logically related 3. All elements of a system are controlled in a manner to achieve the system goal • A computer is a system as it comprises of integrated components (input unit, output unit, storage unit, and CPU) that work together to perform the steps called for in the executing program