Computer science

UNIT-1 Introduction and Evolution of Computer 1.1.  Concept and Characteristics of Computer 1.2.  Application of Computers 1.3.  History of Computer: Mechanical Calculating era, Electro-Mechanical era, Electronic computers era. 1.4.  Generation of Computers: First, Second, Third, Fourth and Fifth Generation(AI) and its features, 1.5.  Computer speed and Measurement Unit

Unit-1 Introduction and Evolution of Computer

Definition of Computer

@ Computer is an advanced electronic device which takes raw data as input from the user and processes these data under the control of a set of instruction (program) and gives output.

@ A computer is an electronic device that manipulates information or data provided by user and process them which can be stored, retrieved at the time of necessity.

@ Computer is an electronic device that can perform mathematical calculations and logical operations at a very high speed.

@ Computer is an advance electronic device that must be completed IPO cycle.

@ A Computer is a collection of hardware and software components that help us to complete many different asks at enormous speed.

@ Computer is a programmable machine that stores and retrieves data and performs mathematical calculations as well as logical operations.

@ It can process both numerical and non-numerical (arithmetical and logical) calculations.

@ Computer is an electronic data processing device which

ü  accepts and stores data input,

ü  processes the data input, and

ü  Generates the output in a required format.

Functionalities of a computer

Any digital computer carries out five functions in gross terms:

ü  Takes data as input.

ü  Stores the data/instructions in its memory and use them when required.

ü  Processes the data and converts it into useful information.

ü  Generates the output

ü  Controls all the above four steps.

The term computer is derived from the Latin term ‘computare’, this means to calculate/count or programmable machine. The computer stands for:-

C = Command or Common. O = Operating or Obedient. M = Machine. P = Purpose or Provider. U = Useful or User. T= Technology or True. E = Education or Everything. R = Research or Right

IPO cycle

Input                                                                              

         Input is the raw information entered into a computer from the input devices. It is the collection of alphabets, digits, symbols, special character, graphics (picture or photo), audio, video etc. Input is always seen. Keyboard, Mouse, Joysticks, Scanner, Light pen, Touch pad, Digitizer etc are some of the input devices.

Process

         Process is operation of data as per given instruction. It is totally internal process of the computer system. CPU is the main processing device. Process is always unseen.

Output

         Output is the processed data (information) given by computer after data processing. We can save these outputs in the storage device for the future use. Monitor (screen), Printer etc are some of the output devices.

The main parts of Computer system

ü  CPU (Central Processing Unit).

ü  VDU (Visual Display Unit) or Monitor.

ü  Mouse.

ü  Keyboard.

ü  Printer.

ü  Scanner etc.

ü  UPS

Feature/ Characteristics of Computer.

ü  Speed.

ü  Electronic.

ü  Non-Intelligent.

ü  Word Length.

ü  High Storage Capacity.

ü  Automatic.

ü  Accuracy.

ü  Diligence.

ü  Versatility.

ü  Reliability.

ü  Multimedia supports.

Speed

 A Computer can perform very complex calculations at very enormous speed. One second is very long time period for the computer. Therefore, the computer speed varies from microsecond to nanosecond, even picoseconds.  Generally, the speed of computer is measured in terms of fraction of second.

• Second(s)-Second (1/1)                                                                                  -10^-0Hz
• Milliseconds – One thousandth of a second (1/1000)                                                -10^-3KHz
• Microseconds – One Millionth of a second (1/1000000).                              -10^-6MHz
• Nanoseconds – One billionth of a second (1/1000000000).                           -10^-9GHz
• Picoseconds – One trillionth of a second (1/1000000000000).                      -10^-12THz
• Femto second(fs)- One quadrillionth of second(1/1000000000000000)       -10^-15PHz

·         Alto second(As)- One of Femtosecond 1/10000000000000000000)                        -10-18EHz

Storage

A computer has the ability to store a large volume data permanently. User can use this data at any time. The storing capacity of computer is generally expressed in Bytes. Normally one byte stores one character of data. The storage capacity is measured in terms of:

0 or 1	1 Bit
4 Bit	1 Nibble
8 Bits or 2 Nibble	1 Byte
1 Byte	1 Character
1024 Bytes	1 Kilobyte(KB)
1024 kilo Bytes	1 Megabyte(MB)
1024 Mega Bytes	1 Gigabyte(GB)
1024 Giga Bytes	1 Terabyte(TB)
1024 Terabytes	1 Petabyte(PB)
1024 Petabytes	1 Exabyte(EB)
1024 Exabytes	1 Zeta Byte(ZB)
1024 Zetabytes	1 Yotta Byte (YB)

Accuracy

Computer always performs its tasks without making any mistake if the instruction is provided correctly. So the accuracy of computer is cent percent.

Versatility           

Versatile means ability to perform various tasks. A Computer has a wide range of application and is used in different fields such as education, science & technology, astronomy, business, entertainment, medicines etc.

Diligence

Computer is capable of doing the required tasks again and again without affecting its speed, accuracy and efficiency.

Reliability

 Computer output is generally very reliable, if the input data and instruction is correct. Incorrect data and unreliable programs give us computer errors and wrong results, the computer is 100% accurate, and it is reliable.

Automatic          

 Computer can be programmed to perform a series of complex tasks automatically. So, the computer has been used for quality control in industries. For example: If we can double click on Ms Word file that can automatically open & convert it into useful format.

Non-intelligent

Computer is a dumb machine and it cannot do any work without instruction from the user. So a computer cannot take its own decision as we can.

Word Length

Word Length refers to the number of bits that the CPU can process in parallel at a time. Modern processors, including embedded systems, usually have a word length of 8, 16, 24, 32, 64 bits, while modern general purpose computers usually use 32 or 64 bits. The power of computer depends upon the word length that makes the more powerful computer.

Electronic

Limitations of Computer

Although computer are very useful device and applied n various fields but there are limitations of computer.

@ Computer does not have its own intelligence. It is a dull machine.

@ Computers cannot memorize as long as they are no given the instruction to store in the secondary storage

@ Instructions are needed to perform any task.

Advantages of Computer

@ It is a reliable machine and performs the task with 100% accuracy rate.

@ Comparing with human being it is much faster.

@ It can be very useful while doing repeated tasks.

@ It is versatile as it can do many types of jobs once at a time.

@ They have large storage capacity, so we can store large amount of data for

Disadvantages of Computer

@ Computer is expensive and still not affordable.

@ Repair and maintenance is required frequently.

@ People are becoming too much dependent on computers.

@ Very difficult to maintain the privacy.

@ Skilled user is required to work with the computer.

@ It cannot be used on the dusty and the rough environment.

@ To increase unemployeement.

@ To increase laziness.

@ To damage our eyes.

@ Dangerous of electricity.

 Application of Computer

Computer is used in large areas such as banking, education, hospital, industries, research, hospital, data processing, science and engineering, offices, railways, advertisement, communication, library, simulation, weather forecasting etc.

a)      Banking & Financial Company - Computer are used in bank and financial company for electronic money transfer, statistical report, voucher, ledger, balance sheet etc.

b)      Education - Computer can be used as teaching learning tool, result processing, students' data processing, question preparation, handouts and note preparation etc.

c)      Industries - Industrial research, budgeting, process control all are computer based in modern industries.

d)     Hospital - In hospitals, computers are applied in medicine, surgery, research, diagnose disease etc.

e)      Science & Engineering - Computer is a strong tool for every branch of engineering such as civil, electrical, computer, aeronautic, ceramics, chemical etc.

f)       Advertisements - Computers are used for advertisement such as business advertisement, film advertisement. It is also used to make cartoon films, special effects and image processing.

g)      Communications - E-mail, e-fax, internet etc are computer based communications. The computer and Internet integration is the backbone of recent communication.

h)      Library - Computer software are used for the management of library. It is used for keeping books, borrowing books, updating the records etc.

Data processing

Data processing is the process of transforming data (raw material of information) into useful information by the computer is called data processing. During data processing the following operations take place.

v    Input and output operations.

v    Text manipulation and calculation operations.

v    Logical and comparison operations.

                                               Data and Information

Data	Information
Data is a collection of raw facts and figures about a person, place and things.	Information is processed data by the computer after data processing.
Data is unorganized.	Information is organized.
Data is not arranged.	Information is arranged.
Data is meaningless information.	Information is meaningful.
Data is input.	Information is output.
Examples: 2, (, &, ram, pen, bench etc.	Examples: Ram is a boy, Pen is writing tool. etc

History of Computers

The history of computer starts from 4000 years ago. History of computer means the gradual change in the concept over a long period of time. According to the technology and concept used on devices, we have three types of calculating devices:

• Early development mechanical devices
• Electro mechanical computers
• Electronic computers.

Mechanical Calculating Devices

a)      Abacus

• Created by Chinese about 3000 years ago.
• The first mechanical aid to calculations.
• Calculations are performed by manipulating the beads.
• It is a rectangular box, divided into two parts by mid bar, upper part is called heaven consists of two beads and each bead equal to value 5 and lower part is called earth, consists of five beads and each bead equal to value 1.

b)      Napier’s Bone

·         Napier’s bones is a multiplication tool invented in 1617 AD by mathematician Johan Napier of Scotland.

·         Multiplication tables were inscribed on strips of wood or bone.

·         Possible to perform calculations with two numbers.

·         It is mainly used for multiplication table.

·         He also developed the concept of logarithm (logarithm table) in 1614 AD

c)      Slide Rule

• Invented by William Oughtred (1574-1660), an English mathematician in 1620.
• An analog device used the principle of logarithms.
• Could perform simple multiplication and division problems.
• Consists of 2 graduated scales, during calculation time, small scale sliding over larger scale and the result was obtained by viewing the scale. 

d)     Pascaline

• Developed by Blaise Pascal (1623-1662) in 1642 to help his father’s tax work.
• It contains eight dials, gears and wheels.
• It was capable of performing additions and subtractions up to 8 digits.
• It could add and subtract by the movement of wheels, not used for division and multiplication.

e)      Stepped Reckoner

• Developed by Gottfried Wilhelm Von Leibniz (1646-1716), a German Mathematician & philosopher in 1671.
• It could evaluate square roots by series of stepped additions.
• The centerpiece of this machine was its stepped-drum gear design.
• Could perform all four of the basic arithmetic functions – addition, subtraction, multiplication and division.

f)       Difference Engine

• Designed by Charles Babbage (1792 – 1871) an English mathematician, in 1822.
• It could solve equations.
• This project could not be completed due to lack of funds.
• It is housed in the Science Museum, London and is till in perfect working order.

g)      Analytical Engine

• Developed by Charles Babbage in 1833.
• It had a ‘store’ for storing data and intermediate results.
• It had an output device to produce printed results.
• It had a unit for calculation called ‘mill’.
• All the modern computers are based on analytical engine (input-process-output).

h)      Hollerith Tabulator

• Developed by an American Dr. Herman Hollerith (1869-1926) in 1887.
• It used punched cards for input, output and instructions.
• This machine was used by American Department of Census to compile their 1890 census.
• In 1896, he founded the tabulating machine company which was renamed as IBM (International Business Machine) later.

Charles Babbage (1792-1871)

• A professor of mathematics developed a machine called Difference Engine in 1822.
• In 1833, he developed the Analytical Engine.
• He is known as the ‘Father of the Modern Computer’ as his invention Analytical Engine had far more of the characteristics of modern computers.

Lady Augusta Ada Lovelace (1816-1852)

• An English mathematician (daughter of English Poet Lord Byron) carried forward the work of Charles Babbage.
• She developed programs for performing mathematical calculation on the Analytical Engine.
• She was the first computer programmer.
• One programming language ‘Ada’ was named after her.

Electro-Mechanical Computers

a)      Mark-I

·         Designed by Howard Aiken (1900-1973), a Harvard engineer in 1937.

·         It was the first automatic electromechanical computer.

·         It was 51 ft. long, 8 ft. tall and 3 ft. wide having 18000 vacuum tubes.

·         It used instructions stored in paper tapes and punched cards.

·         It consists of 7 lakhs 50 thousands parts.

b)      ABC (Atanasoff-Berry Computer)

·         First electromechanical digital computer.

·         Built in 1937-1942 at Lowa State University by John V. Atanasoff and Clifford Berry.

·         It introduced the ideas of binary arithmetic and logic circuit.

·         It used punch cards as secondary storage.

Electronic Computers

a)      ENIAC (Electronic Numerical Integrator and Calculator)

·         Designed by Dr. John W. Mauchly and Dr. J. P. Eckert, completed in 1946.

·         It was built from 18,000 vacuum tubes, and 70,000 resistors.

·         Power consumption – 50,00,000 Kilowatt and floor space – 1,800 square feet.

·         It could add two numbers in 200 microseconds and multiplication of two numbers in 2800 microseconds.

b)      EDSAC ( Electronic Delay Storage Automatic Computer)

·         Designed by Maurice Wilkes at Cambridge University, mathematical laboratory in 1947.

·         It was the first operational stored-program computer.

·         It contains 3000 vacuum tubes and operated on 30 Kilowatt.

·         It used a mercury delay line storage system.

c)      EDVAC (Electronic Discrete Variable Automatic Computer)

·         Designed by J. Mauchly and J.P. Eckert at Pennsylvania University and was completed in 1950.

·         It included a stored-program, a central processor and a memory for both data and programs.

d)      UNIVAC (Universal Automatic Computer)

• Produced by Universal Accounting Company & set up by John Mauchly and J.P. Eckert in 1951.
• It consisted of magnetic tape for data input and output.
• It was the first general-purpose electronic digital computer designed for commercial use.

Computer Generation         

       A continues stage of computer who continue develop the computer system is called computer generation.  The generation of computer means the gap between the developments of the computer in terms of the technologies. Computer generation depends on the device and technology of computer hardware and software, timeline, cost, speed, size, accuracy and reliability. There are totally five computer generations known till date.

    First Generation of Computer (1946-1959)

ü  Major components – Vacuum Tubes

ü  Very slow, large in size, consumed a lot of electrical power.

ü  The operating speed was measured in terms of milliseconds.

ü  Storage capacity was too small only 1 to 4Kb.

ü  Used stored program concept.

ü  For input: - Punched cards.

ü  For output: - paper, punched cards.                

ü  Language: - Supported machine language only

ü  Storage: - Punched paper tape, magnetic tape etc.

ü  Generate lots of heat.

ü  Programming mainly at the hardware level.

ü  Non-portable

ü  Need of A.C.

ü  Few 1^st Gen. Computers – Mark – I, ENIAC, EDVAC, EDSAC, UNIVAC etc.

Second generation computer (1959-1965)

ü  Major components – Transistors instead of vacuum tube

ü  Smaller and faster than first generations computers.

ü  The operating speed was measured in terms of microseconds.

ü  Magnetic tapes were used as secondary storage media.

ü  Consumed less electricity, Generated less heat as compared to first generation computers

ü  Still very costly

ü  A.C. needed

ü  Supported machine and assembly languages

ü  For technology or electronic circuitry: - Transistor.

ü  For input: - Punched cards.

ü  For output: - paper.      

ü  Language: - Assembly language.

ü  Storage: - magnetic cores, magnetic storage cores etc.

ü  Programming mainly at the hardware level.

·         Few 2^nd Gen. Computers - LEO Mark III, ATLAC, UNIVAC I, ICL 1901, IBM 1620, 1400, 7000,CDC 1604, 3600, 160A, 3600,  Honeywell 800, 400 series etc.

Third generation computer (1965-1971)

ü  Major components – IC (Integrated Circuits) instead of vacuum tubes and transistor.

ü  Smaller size, Generated less heat, Faster, Lesser maintenance, still costly.

ü  High-level languages (FORTRAN-II TO IV, COBOL, PASCAL PL/1, BASIC, ALGOL-68 etc.) were used during this generation

ü  A.C needed.

ü  Consumed lesser electricity.

ü  Supported high-level language,

ü  Used high level language for giving instructions.

ü  For technology or electronic circuitry: - LSI, MSI

ü  For input: - Punched cards, keyboard.

ü  For output: - paper, monitor.                

ü  Language: - High level language.

ü  Storage: - Magnetic disks, magnetic tapes etc.

ü  Programming did not dependent on the hardware level.

ü  RAM and ROM were used for memory.

ü  High operating speed, multiprogramming, multiprocessing.

ü  Mainframe and minicomputer were introduced in this generation.

ü  Few 3^rd Gen. Computers - IBM 360 Series, ICL 1900 Series, VAX 1/780, IBM-360 series, Honeywell-6000 series, PDP(Personal Data Processor), IBM-370/168, PDP-8, PDP-11 series, CDC 7000, 7600, TDC-316, control data 3300, 6600 ,7600, Burroughs-6700 etc

Fourth generation computer (1975 – present)

ü  Major components: - microprocessor (VLSI).

ü  The size was greatly reduced.

ü  In this generation time sharing, real time, networks, distributed operating system were used.

ü  All the high-level languages like C, C++, DBASE etc., were used in this generation.

ü  No A.C. needed, Concept of internet was introduced

ü  Portable and reliable, Very small size, Pipeline processing

ü  For technology or electronic circuitry: - Microprocessor.

ü  For input: - keyboard, mouse, scanner, digitizer etc.

ü  For output: -monitor, printer, plotter etc.                

ü  Language: - High level language (non-procedural language).

ü  Storage: - Magnetic disks, magnetic tapes, optical disk, floppy disk etc.

ü  Programming did not dependent on the hardware level.

ü  First microprocessor 4004 was introduced by American Intel Corporation in1971.

ü  They have very high speed of processing; they are 100 % accurate, reliable, diligent and versatile.

ü  The size varies from desktop to laptop or palmtop.

ü  Few 4^th Gen. Computers – Pentium I/II/III/IV, HP 3033, APPLE II, DEC 10, STAR 1000, PDP 11, CRAY-1(Super Computer), CRAY-X-MP(Super Computer), IBM PC, Apple/Macintosh Microcomputer, IBM-3080, IBM system/370, UNVAC 1108, UNVAC 9000 series, HP-9000, HP-3000, AMD athelon, Cray 2 XMP,

Fifth generation computer (coming generation)

AI includes:

ü  Robotics, Neural Networks, Game Playing

ü  Development of expert systems to make decisions in real life situations.

ü  Natural language understanding and generation.

The main features of fifth generation are:

ü  Major components – ULSI (Ultra Large Scale Integration)

ü  ULSI technology: - Bio Chips (Organic Chips).

ü  Advancement in Parallel Processing

ü  Advancement in Superconductor technology, More user friendly interfaces with multimedia features

ü  All the high-level languages like C and C++, Java, .Net etc., are used in this generation.

ü  The concept of AI (Artificial Intelligence) has been introduced to take its own decision.

ü  Bio chips and Gallium Arsenide (GaAs) are used as memory devices.

ü  Extremely high-speed processing capability.

ü  Large uses of natural language processing and user friendly.

ü  Few 5^th Gen. Computers projects – ICOT program in Japan, MCC project in the USA etc.

ü  Availability of very powerful and compact computers at cheaper rates

ü  Examples: -Desktop, Laptop. Notebook, Ultra Book, Chrome Book

Some popular terms:

Vacuum Tubes

• The vacuum tube was invented by Lee De Forest in 1907.
• Lee De Forest was born o\in Council Bluffs, Lowa (USA) in August 26, 1873.
• It is a set of metal electrodes and grids contained in a glass or metal tube.
• The Vacuum tube was used in First generations computers.
• Formerly used for amplification and switching in electronic circuits, now used in CRT (Cathode Ray Tube).

Transistors

• Short for: transfer resistor
• It is a solid state semi-conductor device which can be used for amplification, switching, voltage stabilization, signal modulation etc.
• It transfers a signal from a low resistance to high resistance.
• It was invented in 1947 by three Bell Lab scientists John Bardeen, Walter Brattain, and William Shockley.
• Used in second generation computers as major components.

Integrated Circuits (IC)

• An IC is a circuit consisting of a large number of electronic components placed on a single silicon chip by a photolithographic process.
• Jack Kilby invented it in 1958.
• Used in third generation computers as major components.
• IC is used for a variety of devices, including microprocessor, audio and video equipment and automobiles.

Microprocessor

• The microprocessor is a computer processor built onto a single piece of silicon, known as a wafer or chip.
• First microprocessor is Intel 4004 developed by American Intel Corporation in 1971.
• Used in fourth generation computers as a major component.

Artificial Intelligence (AI)

A branch of computer science that refers to the use of computer in such a way that they are able to reason and draw, recognize voice and have language processing ability is called AI.

Biochip

The future device will be used in 5th generation computers, made of large organic molecules and a genetically engineered protein is called Biochip.