introduction-and-evolution-of-computer file · Web viewThis process of conversion of raw material into the refined form is nothing but the data ... the Latin word “Computare

Input Process Output

Instruction[Mouse/

Keyboard]

[Input Devices]- Keyboard- Mouse- Microphone- Light Pen- Touch Pad- Joystick etc...

[CPU]Central Processing Unit

(Result)(Result)(Unseen)(Data)

I ntro d uction & E v olution of Co m puter COMPUTER SCIENCE

Computer Science is the study of the operating principles of computers, computer programming languages and algorithms for solving theoretical as well as practical problems. It involves the development and use f devices for processing information. It also deals with advantages and disadvantages of computer, its features, applications field and its impact on the society. Information in one form is presented to the device (input information) and information in other form is acquired from it (output information). This process of conversion of raw material into the refined form is nothing but the data processing. Data processing may be defined as the process of transforming data (raw material of information) into useful information by the computer.

What is Computer?The term ‘Computer’ is derived from the Latin word “Computare”, this means to

calculate.Computer is an advance electronic device which takes raw data as input from the

user and processes these data under the control of set of instructions (called program) and gives the result (output). It also saves output for the future use. It can process both numerical and non-numerical (arithmetic and logical) calculations.

In (Chetan Thapa Magar) my words, “Computer is a programmable machine that stores and retrieves data and performs high speed logical and mathematical operations under [Input-Process-Output] principles introduced by Charles Babbage.”

IPO (Input-Process-Output) Cycle:

Prepared By: Chetan Thapa Magarwww.facebook.com/MeIDoKoXorachetanthapa.wordpress.com[Page 1]

[Output Device]- Monitor

- Printer/Plotters

Input (Data):Input is the raw information entered into a computer from the input devices. It is the collection of letters, numbers, images etc.Process:Process is the operation of data as per given instruction. It is totally internal process of the computer system. CPU is the main Processing Device.Output:Output is the process data given by computer after data processing. Output is also called as Result. We can save these results in the storage devices for future use.

Characteristics of ComputerSpeed:Computer performs complex calculation at a very high speed. This speed varies from a few micro second to nanoseconds. This is the major factor, which is mainly responsible for the development of computers.Fractions of Seconds:1 Millisecond = 1/1000th of a Second (10-3)1 Microsecond = 1/1000000th of Second (10-6)1 Nanosecond =1/1000000000th of Second (10-9)1 Pico Second =1/1000000000000th of a Second (10-12)1 Pasto Seconds =1/1000000000000000th of a Second (10-15)

Accuracy:Computers are very accurate. We know that the computer perform any task

under the set of instruction called program. So, it doesn’t do anything without program. Thus, it can perform any operation accurately.Computer always gives 100% actual result (Output), if the user provides correct input and instructions. If any mistakes occur in any calculation they are due to manual error but not of computer. Since, it is 100% accurate and reliable.

Storage Capacity:The computers have the ability to stores a huge amount of data in the

secondary devices like floppy and hard disk. The stored information also can retrieve immediately. This helps in analyzing data and taking quick decisions. The storing capacity of a computer is expressed in Bytes. Normally one byte stores one character of data.0, 1 = 1 Bit4 Bits = 1 Nibble8 Bits (2 Nibble) = 1 Byte1 Byte = 1 Character1024 Byte = 1 KB (Kilobyte)1024 KB = 1 MB (Megabyte)1024 MB = 1 GB (Gigabyte)1024 GB = 1 TB (Terabyte)1024 TB = 1 PB (Pettabyte)

Versatility:


Computer is being used in different fields such as offices, schools, hospitals, etc. to perform various tasks. Versatile means ability to perform various task & computer can capable to do so. A computer can process any kind of data.Diligence:

Diligence is a capability of performing repeated operation without any tiredness and any mistakes. A computer is capable of performing the required task continuously with the same speed, accuracy, and efficient without any error. This characteristic of computer makes it useful for repetitive jobs like process control and quality control.Reliability:

Computer output is generally very reliable, if the input data and instruction is correct. Incorrect data and unreliable programs give us computer error and wrong result. Since the computer is 100% accurate and reliable.Indescribable benefits:

Many organizations and companies use computers for indescribable benefits such as flexibility, business growth and the psychological factor for attracting consumers to buy their products or services.

Uses of ComputerComputer, one of the most powerful machine today, is being used everywhere.

Let’s discuss the uses of computer on various sectors of our society.Business and Industry:

The uses of computers in business/offices improve their working efficiency. Record keeping becomes very easy. Information can be searched immediately. The use of computer in industries has improved their efficiency. The cost of production goes down and quality of products is improved. Unpleasant and hazardous work can be performed by using robots. Working hours of laborers are reduced; they get more leisure.Health Care:

Computers are also being used for planning and control purposes by health-care professionals. Computer equipment is used to measure pulse rate, blood pressure and other vital signs. This leads to correct and fast diagnosis. Medical researchers are using computers as a tool in their search for cures of deadly diseases like Cancer and AIDS.Education:

Computers are playing an important role in education. Once can get lessons on certain topics, special lectures prepared by experts etc... On the screen as many times as he/she wants until he/she understands the topic. It is working as teachers or helping teachers in educational institutions.Science and Technology:

Thousands of scientific applications are processed daily, on the computers. One of the most important daily activities is weather fore-casting, which involves solution of mathematical equations using worldwide data about pressure, temperature, humidity and other values.Humanities:


In recent years, computer have become popular among people having interests in history, literature, music, graphics, art and other branches of humanities.Communication:

Computers are capable of manipulating and transmitting texts at very fast rate. Sitting at home, anybody may do office work, bank transactions, marketing, purchase of shares, and reservation of place & bus tickets and so on. Officers and managers can contact any branch office anywhere in the world through the computer network. Text, voice, data and picture can easily be transmitted nowadays using modern communication systems, which heavily depend upon computers. Information is transmitted over long distance through satellites.Government:

Various departments of the Government use computer for their planning, control and law enforcement activities. To name a few - Traffic, Tourism, Information & Broadcasting, Education, Aviation and many others.Recreation and Entertainment:

Our entertainment and pleasure-time have also been affected by computerization. For examples:

In movies , computer generated graphics give freedom to designers so that special effects and even imaginary characters can play a part in making movies, videos, and commercials.

In sports , computers compile statistics, sell tickets, create training programs and diets for athletes, and suggest game plan strategies based on the competitor’s past performance.

In restaurants , almost everyone has eaten food where the clerk enters an order by indicating choices on a rather unusual looking cash register; the device directly enters the actual data into a computer, and calculates the cost & then prints a receipt.

Capabilities and limitation of ComputerComputers are a device, which is capable of doing almost all the works, which

can be programmed by the user. But there are some functions, which are impossible, for a computer to perform. Following are some capabilities and limitation of a computer.Capabilities:-

1) Computers can do jobs with 100% accuracy & in a very fast speed in comparison to any other devices or humans.

2) It is possible to show & do the things, which are impossible for humans.3) Computer provides faster & cheaper communication with the use of various

communication technologies.4) It can perform almost all the works but for any purpose, user must provide proper

program & necessary hardware. Limitations:1) A computer is a dull machine. It doesn’t have intelligence on it. So, whatever it

does, that is with the help of programs & devices developed by humans.2) If any error occurs in its structure or circuitry, then the output given by it is wrong

which is very hard to tackle.3) The Computer is totally depended on programmed to do any task.

Advantage of computerPrepared By: Chetan Thapa Magarwww.facebook.com/MeIDoKoXorachetanthapa.wordpress.com[Page 4]

1) Computer is very much faster than a human.2) Computers are 100% accurate and much more reliable than any other device s

well as human being.3) It is very much useful for repeated jobs, which is difficult & tedious for human to

do.4) It can be used in multiple fields.5) With the help of computer, impossible things are easy to show and simulate.6) Because of the availability of storage, programs can be modified to add features

for several purposes.

Disadvantage of ComputerWe see that computer have great impact on our society. They are even

changing the way we work. But even there are certain disadvantages also. Some of them are as follow:-

1) There may be cases of misuse in banks, leakage or misuse of personal information, etc.

2) It is electronic machine so there is much danger of electronic shock and other physical damages.

3) In underdeveloped/developing country like Nepal, it increases piracy of intellectual properties in big order/amount.

4) It increases dependency on machine. So even for very simple calculation people need them to calculate.

5) Since it is much reliable, so some times the failure programs can produce unreliable information and cause loss of data in a great extent.

6) Since computer are used in sensitive areas like natural defense, civil aviation, etc... So even simple mistakes can causes loss of life and properties.

History of ComputerYou will be amazed to know that this computer sitting so closely on your desk

today is the result of several hundred years of development. The computing history starts from early civilization of 4000 years ago. History of computer means the gradual change in the concept of computer over a long period of time. Around fifth century, Hindu philosophers developed new method of counting from 0 to 9. Counting the numbers from o to 9 can be performed with the help of fingers but it became difficult & not sufficient. So instead of the fingers, probably people use sticks, marks on the earth, scratches & symbols on stones, knots on the rope etc. After that the development of counting started from the development of simple counting device called ABACUS. History of computer is divided into three eras which are Mechanical Calculating Era, Electro-Mechanical Era and Electronic Era.Abacus:-

Abacus is the early counting and calculating device that was developed by the Chinese people. It was made of a wooden frame on which there were strings. The frame was divided into two parts, Heaven and Earth, by a mid-bar. Each string in heaven has two beads each having the value of five units and each string on earth had five beads each having the value of one unit. It was used to add, subtract, simple divide and multiply.Napier’s bones:-


In 1614 AD, a Scottish mathematician John Napier discovered the concept of Logarithms. In 1617 AD, he constructed a set of rods called Napier’s bones for doing mathematical calculation easily. It consisted of eleven sets of bone rods on which numbers were engraved. It was used for multiplication. It was based on the principle of performing multiplication by the addition of logarithms.

Slide Rule:-After the invention of logarithm in 1617 AD, William OughtRed invented the Slide

Rule in 1620. This device was made on the principle of logarithms. Slide Rule consists of two graduated scales, one small and other large one. The calculation was done by sliding the smaller scale over the large scale and the result was obtained by viewing the scales. It was used for division. It was used by engineers till 1970s but then replaced by pocket calculator.Pascaline/Pascal’s Calculating:-

Pascaline was developed by Blaise Pascal in 1642 AD. It was a mechanical calculator that used toothed wheels and gears. The numbers were written on the wheels and the calculation was done by dialing the numbers. It was used to add, subtract, multiply and divide.Leibniz’s Calculator/Stepped Reckonor:-

It was made by a German philosopher Gottrifed Wilhelm von Leibniz (G.V. Leibniz) in 1671 AD. It was based on Pascal’s principle. But it used gears, toothed wheels and drums. It was able to add, subtract, multiply, divide and even find square roots.Difference Engine:-

In 1822 AD, an English mathematician, Charles Babbage (Professor of Mathematics at Cambridge University) invented a machine called Different Engine with mechanical memory to store results. It was based on the difference tables of squares of the numbers. Due to which it got its name as Difference Engine.Analytical Engine:-

It was also developed by Charles Babbage in 1830s. It consisted of input unit for taking data and instructions, mill for performing calculation, memory (Punch-Card) with a suitable output device that was used in giving the final result. It was designed to calculate up to 20 decimal places. The same principle [Input-Process-Output] of Analytical Engine is used in the modern computer, so he is called the “Father of Computer Science”. Using the principles of Charles Babbage, about 100 years later, Mark-I (1) was developed by Howard Aiken in 1937.

The Analytical Engine was never completed due to the lack of techniques and technology because of which he was unable to get all the parts that he wanted in his machine.Lady Augusta Ada Lovelace:-

One of the great supporters of Charles Babbage was Lady Augusta Ada Lovelace (The daughter of famous poet, Lord Byron). She convinced Babbage to use binary concept in his Analytical Engine and wrote different types of programs that were used in Babbage machines, so she is remembered as the “First Programmer” in the history of computer science and has credit a computer language called ADA named after her.George Boole:-Prepared By: Chetan Thapa Magarwww.facebook.com/MeIDoKoXorachetanthapa.wordpress.com[Page 6]

George Boole was the one of the greatest English Mathematician who contributed greatly to the study of symbolic logic during the ‘19 century’s (1950s). He was very famous for discovery of mathematical logic called “Boolean Algebra”. It was the foundation of the modern electronic computer architecture by 0 or 1 for the electric circuit. Since switching mechanisms at the time could only produce the two actions ‘On & Off ’, Boolean algebra provided engineers a medium to communicate with their computers.Dr. Herman Hollerith:-

He was the first person to use punched card practically on his Census Tabulating Machine in 1880s. The information is stored as holes in cards, which are interpreted by machines with electronic sensors. The cards were punched by a machine called Punch Card Machine or Hollerith’s Tabulating Machine. Then he established Tabulating Machine Company to sell his products. Later, when other companies merged with TMC, new company were established under the name International Business Machine Company and he became the founder of IBM. It is the world’s leading computer manufacturing company.Mark-I (1):-

In the late 1930s, next important event was added in the History of Computer; the electromechanical computer was born with the development of MARK-I in 1944 by Howard Aiken with the help of IBM. It also used punch cards as designed for Difference Engine. It was 51 Ft. long, 8 Ft. high and 13 Ft. wide in size. It used 18,000 valves (vacuum tubes), large numbers of switches and resistors. It was used to produce ballistics tables in 2nd world war. All output was displayed on electric typewriter.Later after modifying Mark-I; Mark-II was made by Howard Aiken in 1947. It contains 19,000 vacuum tubes s a main component. It was faster than the comparison to Mark-I. A unique feature of Mark-II is that it had built-in hardware for several function such as the reciprocal, squares root, logarithm, exponential and some trigonometric functions. It took 5-12 sec. to execute.Atansoff Berry Computer (ABC):-

John Von Atansoff was a professor of physics and mathematics at IOWA state university. Getting the help of his student, Clifford Berry, he invented a computer, built in 1937-1942 AD to help his graduate students to solve different and difficult equation and other mathematical equations. It used 18,000 vacuum tubes as a processor and other 45 vacuum tubes for internal logic & capacitors for storage of electrical charge.John Von Neumann:-

He was the mathematician who discovered stored program technology in 1945 AD. This became the fundamental program technology for modern digital computer. This technique made computer programming and computing faster, more flexible and more efficient. The key element of the J.V. Neumann architecture was the central processing unit, which allowed all computer functions to be co-ordinate through a single source. He was also famous as “Father of Stored Program”.Electronic Numerical Integrator and Calculator (ENIAC):-

It is the first electronic computer that was developed by John Mauchly and John Prisper Eckert in 1947. It was based on the decimal number system. Vacuum Tubes were used as a main component in it. There were 70,000 resistors, 10,000 condensers and 6,000 switches. It weighed 30 tones and occupied a space 3,000 cubic feet. It could calculate 300 times faster than any calculating device at that time and it was also based on decimal number.


Electronic Delay Storage Automatic Computer (EDSAC):-In 1949, EDSAC was developed by Mauric Wikes by applying J.V. Neumann’s

“Stored Program Technique”. It contained 3,000 vacuums tubes and used mercury delay lines for memory. Program was input using paper-tape and output result were passed to a teleprinter. Additionally, EDSAC is created as using on the first assemblers called “Initial Orders”, which allowed it to be programmed symbolically instead of using machine code. It was started to invent after EDVAC but completed before it.Electronic Descrete Variable Automatic Calculator (EDVAC):-

In 1952, EDVAC was developed by J.W Mauchly and J. P. Eckert with the help of A. Burks, Goldstine and Neumann. This Machine was used to store data and information as well as the instructions. This computer operates electronically. It was a binary serial computer with automatic addition, subtraction, multiplication, division and automatic checking capacity with an ultra-sonic serial memory capacity of 1,000 uu-bit words.Universal Automatic Computer (UNIVAC):-

J.W. Mauchly and J.P. Eckert founded their own company in 1946 and began to work on the Universal Automatic Computer. It was the first general purpose electronic digital computer made for business and administrative use. Before it, mostly the computers were used for census and defense department. It was completed in 1951 AD.History of Computer in Nepal]

The first computer bought in Nepal was IBM 1401 which was brought by the Government in lease for Population Census of 1972 AD (2028 B.S.). Later, in 1975 (2031 BS) Yantrik Sarinikaran Kendra (Electronic Data Processing Center) was established which was later called as National Computer Center (NCC). Again, for the population census of 2038 BS ICL 2950/10 computer having 64 terminals was brought in Nepal by the aid of UNDP. After 2039 B.S. microcomputer like; Apple, Vector, Sirus were introduced in the capital. From that time computers have been used in different government sectors like Banking, Agriculture, and Universities etc. Now there are more than thousands of computer institutes providing computer education, assembling, maintenance etc. in Nepal.Generation of Computer

Depending on the device used, system architecture, processing mode and language used in the computers are categorized in the following five generation. The development of different types of memory devices has given a sequence of development of computers from mainframe to micro-computers. In the development of computers there is a lot of change from 1946-1990. This time is divided in different generations by scientists in a conference in 1962.First Generation Computer (1946-1954)

Introduction of the UNIVAC in 1951 marked the beginning of the first generation. J.W Mauchly and J. P. Eckert began to work on the Universal Automatic Computer (UNIVAC) in 1946; so we can considered the duration of First Generation starts from 1946 AD. We can say that those computers using vacuum tubes as a memory unit or a main processor are known as first-generation computers. The vacuum tube consumes a lot of power. The Vacuum tube was developed by LEE DeForest in 1908 AD and use later in computer.Features

1) They used valves or vacuum tubes as their main electronic component.Prepared By: Chetan Thapa Magarwww.facebook.com/MeIDoKoXorachetanthapa.wordpress.com[Page 8]

2) They were large in size, slow in processing and had less storage capacity.3) They consumed lots of electricity and produced lots of heat.4) Their computing capabilities were limited.5) They were not so reliable.6) They used machine level language for programming.7) They were very expensive.Examples of 1st Generation Computer: - ENIAC, UNIVAC, IBM 650 etc.

Second Generation Computer (1955-1964)The invention of Semi-conductor device called ‘Transistor’ had made big

revolution in the field of computer. The transistor developed by “John Eardeen, Willian Shockley & Walter Bretain” in 1947 A.D. replaced Vacuum tube. The second-generation computer used transistors as a memory unit. A transistor could do the work of 1000 vacuum tubes. Second computer are smaller in size, more reliable and faster than first generation computer. Assemble language was used for programming in second generation computer.Features

1) Transistors were used instead of Vacuum Tubes.2) Processing speed is faster than 1st Generation Computers (Micro Second)3) The input and output devices were faster.4) Smaller in size (51 square feet)

Examples of 2nd Generation Computer: - IBM 1400 and 7000 series, PDP8, Control Dat 3600etc.

Third Generation Computer (1965-1974)By the development of a small chip consisting of the capacity of 300 Transistors

first time developed by John Kilbey & Robert Noyce called “Integrated Chip”(IC). The computers, using ICs are considered as Third Generation Computer. They were smaller in size and had higher efficiency in speed & memory capacity. Very soon ICs were replaced by LSI (Large Scale Integration), which consist about 100 components. An IC containing about 100 components is called (LSI) Large Scale Integration.Features

1) They used Integrated Circuit (IC) chips in the place of Transistors.2) Semi-conductor memory device were used.3) The Mini Computers were introduced in this generation.4) They used High Level Language.5) Large Scale Integration (LSI) is developed.6) Storage capacity is increased in Mega Byte (MB).

Examples of 3rd Generation Computer: - IBM 360 Series, UNIVAC 1108, UNIVAC 9000, etc.

Fourth Generation Computer (1975-1990)The development of VLSI (Very large Scale Integration) circuit built in wafer

thin slices of extremely purified silicon crystals and microprocessor enhances the performance of Fourth Generation. The first microprocessor 8008 was developed by American Company (Intel Corporation) in 1991 and in 1974 another more powerful microprocessor 8080 was developed. The microprocessor 8080 was used in early XT computers. Microprocessor based computers fall in fourth generation computer group.The first microcomputer was designed by Steve Wozniak and S. Jobs, named as Apple-I in 1976. IBM also developed microcomputers and it led Apple Corporation by producing Home computers or Personal computers commercially in 1984. They were XT machines, which have been replaced by the 80286 microprocessor.Features


1) VLSI and Microprocessor are used in fourth generation2) Processing speed is very high in Pico Seconds.3) Storage capacity was very high in Giga Byte (GB).4) Input-Output devices were versatile.

Examples of 4th Generation Computer: - Acer, Gateways, Apple, IBM PCs, etc.

Fifth Generation Computer (1990 to incomplete)After 1990, a new generation of a computer called Fifth Generation has been

under development stage. As microprocessors were developed, huge numbers of personal computers were applied in offices, house, many companies attempts are being made to produce more efficient and fast computers. It is estimated that these computers of fifth generation will have an Artificial Intelligence (AI) with a little thinking capacity and they will understand the natural languages.Features

1) Intelligent programming2) High performance multi-processor system3) Easy Human-Computer interfaces4) They have Artificial Intelligence5) Computer will understand natural language6) They will be used BIO-CHIPS, ULSI (Ultra Large Scale Integration)Examples of 5th Generation Computer: - Not Yet Invented Completely_!

( ? )

Notes:1) In 1958 AD, The first computer to use Transistor as a switching device,

IBM 7090, is introduced.2) In 1964 AD, The first computer to used Integrated circuits, IBM 360 is

announced.3) In 1975 AD, The first micro-computer, Altair, is introduced. In the same

year, the first Super computer, Cray-1 is announced.4) In 1976 AD, Digital Equipment Corporation (DEC) introduced its popular

Minicomputer, VAX 11/780.5) In 1977 AD, Steve Wozniak and Steve Jobs establish the company “Apple

Computers”.6) In 1979-82 AD, Bjame Stroustrup of Bell Laboratories in New Jersey

introduces “C with Classes.”7) In 1984 AD, Apple introduces the Macintosh, the first widely available

computer with a “user-friendly” graphical interface using icons, windows, and a mouse device.

8) In 1989 AD, Microsoft Corporation introduces Windows for IBM Computers.


Generation First

Generation Second

GenerationThird

GenerationFourth

GenerationFifth

Generation

CPU Technology Vacuum tube ( Valve )

Transistor Integrated Circuit(IC)

Microprocessor Bio-chips

Memory Device Acoustic delay lines / Valve

Ferrite core / Magnetic core

Memory

Magnetic core/ Semi conductor

memory

Semi conductor memory

Super conductor memory

Permanent Storage Punch card Magnetic tapes Magnetic disk Magnetic and

optical disk New technology

for storage

Programming Language Machine Language

Assembly / High Level Language

High Level Language

High Level Language/4GL

Natural Language

Operating System Human Operator

Batch System Multiprocessing Multiprocessing /

real time / distributed

Intelligent operating system

Speed Very few Kilo

hertz (Mili Second)

Few kilo hertz(at most 58kilo hertz)

(Micro Second)

Mega hertz(around 12

mega hertz) Nano Second

Very high Giga hertz (Pico

second)

Higher than other generation

(Femto-Second)

Time- Duration 1945-1954 1955-1964 1965-1979 1980-1990 1990-Present

Example Mark-I, UNIVAC,EDSAC

IBM-1401, ICL 2950/10

IBM-360,PDP-8, PDP-11,STAR

PENTIUM-PC, CORE2DUO-PC,

APPLE/MACINTOS

Not Yet Invented

Classification of Computer Up to now, there is no clear-cut classification of computer. However, Computers

can be classified or typed in many ways. Some common classifications are summarized below in different groups. These are as follows:-

On the basis of Working PrincipleAnalog Computer

An analog computer is a form of computer that uses the continuously changeable aspects of physical phenomena such as electrical, mechanical, or hydraulic quantities to model the problem being solved. These Computers doesn’t use discrete values, but rather continuous values, processes can’t be reliably repeated with exact equivalence, as they can with turning machines. Analog computers were widely used in scientific & industrial applications. Thermometer, Speedometer, Fuel & Price Indicator in Petrol Pump, etc…are examples of some Analog Computer.

It repeats numbers by a physical quantity; that is, they assign numeric values by physically measuring some actual property, such as the length of an object, an angle created by two lines, or the amount of voltage passing through a point in an electric circuit. The accuracy of the data used in an analog computer is directly related to the precision of its measurements.

Digital ComputerDigital computers are based on discrete quantities & represented with Binary

number. They are based on binary digit. Binary system is such system of numbering in which only 2 digits are used. Those digits are 0 and 1. Meaning of 0 is either Off, False, No, etc... & 1 is On, True, Yes, etc... So the basic principle of these computers is either present or absence of electrical pulses in the signals.

Digital computers are much faster than analog computer & far more accurate. They are the most versatile machine in electronic family. They perform calculation by counting. They are mainly used in airline reservation system, bank check-processing system, military weapons system, etc...Hybrid Computer (Analog + Digital)

Hybrid Computers are computers that exhibit features of Analog computers & Digital computers. It can do any types of tasks of Analog & Digital Computers. They are usually used for special purpose in which input data derived from measurements is converted into digits and processed by computer. They are mostly used in scientific research, industrial application, aero-planes etc.

In Hybrid computer, the digital component normally serves as the controller & provides logical operation, while the analog component normally serves as a solver of differential equation. It can be used to obtain a very good but relatively imprecise seed value, using an analog computer front-end, which is then fed into digital computer iterative process to achieve the final desired degree of precision. Modem, Hybrid Watch, etc. are the best examples of Hybrid Computer.


# Difference Between Analog Computer S.N. Digital Computer

They are generally specific purpose computers. 1 They are general purpose computers.Generally, storage facility is available. 2 Storage facility is availableAccuracy of these types of computers is very less. 3 Accuracy of these types of computers

is very high.Reprogramming is impossible. So they are not flexible. 4 Reprogramming is possible. So they

are flexible.The output generated by analog device is in wave, curve or other graphical form.

5 The output generated by digital device is in digital pulses.

Thermometer, speedometer, seismograph, etc are the e.g. of analog computer.

6 IBM PC, Mac., Palmtop, Mobile, etc. are e.g. Of digital computer.

On the basis of Size

Mainframe ComputerThe term Mainframe computer was created to distinguish the traditional large

institutional computer intended to service multiple users from the smaller, single user machines. These computers are capable of handling and processing very large amount of data quickly. The processing speeds of these computers are Billions Instruction per Seconds (BIPS) & respond up to 100s of billions of users at a time.

Up to 1975 AD, Mainframe computers were used for all data processing, complex engineering designs and scientific computation. Now days, they are generally used in huge organizations and government departments for large-scale data processing like Population Census, Result Processing, Taxation, Custom Office, large multi-national corporation, etc..Mini Computer

Mini Computers are a class of multi-user computers that lie in the middle range of the computing spectrum, in between the smallest mainframe computers and largest single user system (Personal/Mini Computers). The term super-minicomputer was used to distinguish more powerful minicomputers that approached mainframes in capability. Super-mini computers were usually 32-bit at a time when most minicomputers were 16-bit. The contemporary term for minicomputer is midrange computer, such as the higher-end SPARC, POWER & Itanium based system from Oracle Corporation, IBM & Hewlett-Packard (HP).

Mini Computers are medium in size than Super and Mainframe Computers but larger than Micro-Computers. At least 50 people can work at a time. They can use in Local Area Networking. They are specially used in data processing, Programming, Desktop publishing fields, etc...Micro Computer

Micro Computers are the most common kind of computers in use as of 2015. The term “Micro computers” was introduced with the advent of systems based on single chip called microprocessors. The best-known early system was the Altair 8800, introduced in 1975 AD. The term Micro-Computer has practically become an anachronism.


Micro-Computers are also known as Personal Computer or Home Computer. They are extensively used at home, office, school, etc... Micro-Computer can do one task at a time.

Micro-Computer include:- Desktop Computer: - A case & a display, put under & on a desk. In-Car Computer (Carputer):- Built into a car for entertainment, navigation, etc... Game Consoles: - Fixed computers, specialized for entertainment purpose (Video

Game Laptop/Notebook/Palmtop Computer: - Portable & all in one case. Varying size but

other than smart expected to be a full computer without limitation Tablet Computer: - Like laptop, but with a touch-screen, sometimes entirely

replacing physical keyboard Super Computer

Super computers are 64-bit systems computer with 100 MIPS (Millions Instruction per Seconds) speed and 8 MB to 64 MB storage capacity. Super Computer use parallel processing technology instead of sequential or serial processing system.

Super Computers are used in designing complicated machines as supersonic jets, space research, and picture composition for movie films, crystallographic analysis and for weather forecasting. Huge amount of calculations and large volume of data can be processed only in Super Computers with fast speed and large memories. Super Computers are designed to process complex scientific jobs. They are made for special purpose. Super Computers have the largest, fastest and most expensive systems in the world. Examples of Super Computer: - Cray I/II/III, etc.# Difference Between

Mainframe Computer S.N. Micro ComputerThis computer supported about 100 users at a time. 1 This computer supported only one

user at a time.They had massive data storage facility. 2 They had less storage facility

compared to mainframes.It was the fastest, powerful, and most expensive computer of at that time. 3 It was slower and cheaper than

mainframe.They were used by large organizations, agency and government for large scale data processing.

4These computers were used for multitasking, multimedia and networking.

They are huge in size. 5 They are portable.IBM S/370, DEC 10, NEC610 etc. are e.g. of mainframe computer. 6

IBM Pentium PC, Apple/ Macintosh, Zenith, etc. are e.g. of micro computer. On the basis of Brand

IBM ComputersThe Computers manufactured by IBM (International Business Machine) company

are called IBM Computers. IBM is one of the leading companies in computer manufacturing. IBM Computers are more reliable, strong and have high processing speed. IBM Computers are quite expensive than other and of original types. The microcomputers of IBM Company are called IBM PC (PC-Personal Computer).IBM Compatible

Computers developed on the principles of IBM Computers are called IBM Compatibles. It can perform the entire task that an IBM computer does. IBM Compatibles are less expensive than original (IBM) Computers.


Apple/MacintoshThe computers manufactured by the Apple Company are called Apple Computers.

They are specially used in Desktop-Designing. Apple/Macintosh Computers are originals and quite expensive than IBM and IBM Compatibles. The Operating System and other peripherals are completely different than IBM and IBM compatibles.

On the basis of ModelXT

XT stands for extra or extended technology. It is an old technology with very slow processing speed. It is text based system with no GUI (Graphic User Interface) based. Input/Output (I/O) device wasn’t flexible and slower than present devices. Processors like Intel 8080, 8086, 8088 are used in this computer.

ATAT stands for extra or extended technology. At Computers is faster in processing

and can run both GUI and CUI (Character User Interface) based. Input/Output (I/O) devices are interactive, flexible and faster than XT Computers. It was a medium speed processing device. Processors like 80286, 80386, 80486, Pentium I, Pentium II, etc are used in AT Computers.PS/2

PS/2 stands for personal system 2. It is the modification of AT Computer, making the computer faster than AT. It was mostly used in laptops with rechargeable & battery operated system with faster and flexible. In other words PS/2 Computer is being made portable sometimes called a Notebook also. It works like AT Computers and run almost all software and programs.Configuration of Computer System1. Power Supply Unit [Stabilizer, UPS(Uninterruptible Power Supply)]

We all know that, Computer is an electronic device so Electricity is the compulsion to operate it. Each and every component of the computer can sustain a fixed current capacity so; fluctuation of voltage may damage these components. That’s why; we have to use Volt Guard, Stabilizer etc. to maintain the voltage fluctuation.UPS is a power storage device so; it helps to supply power regularly at the time of interruption of electricity.

2. Input DeviceThese devices are used to give raw data (Input) to the computer to perform the

specific tasks. The purpose of input devices is to translate data and information from human-readable format to electrical impulses.

The common input devices are as follow:A) Mouse

The mouse is a pointing input device that is used Visual(Video) Display Unit [VDU] at computer system. It is a small box with a round ball on the bottom and more than one buttons on the top. It is hold in one hand and moved across a flat surface. In all case the pointer is used to move the cursor around the screen. Most pointer manufactures have now adopted the middle wheel or scroll buttons as standard.

A mouse can be divided into three categories:

i) Mechanicalii) Opto-Mechanicaliii) Optical


Based on the method used to interface or to connect the mouse to the main computer system, mouse can be divided into following categories:

# Serial Mouse# Bus (PS/2 mouse)# USB Mouse# Wireless Mouse

In this type of mouse everything is similar to the conventional mouse except that no cable is used to connect the mouse to the computer. Basically there are two type of wireless mouse: Infrared Wireless Mouse and Radio-Controlled Wireless Mouse.

B) Keyboard

This is the most popular data entry system used in almost all modern computers. The most important thing to watch out for is the keyboard connector. If you build an ATX system, you’ll need a keyboard with a PS/2 connector, if you built an AT system, you’ll need keyboard with a DIN connector (Germany’s Deutsche Industries Norm, a committee that set German Standard).

Most new keyboards come across these days have a nice non-click touch. The difference between click and non-click keyboard is their design. Click keyboards are mechanical, whereas non-click keyboards use soft rubber membranes to close contact.

The computer keyboard has three categories of keys:I) Alphanumerical KeysThe alphanumeric keys comprises of alphabets (A-Z and a-z), numbers (0-9) and

other characters and symbols.II) Special KeysThe special keys perform special task. Some of the special keys are Enter,

Backspace, Del , Ins., Shift, ESC, Alt, Ctrl etc.

III) Function KeysThe function keys (F1-F12) are used to perform a set of operation by a single

keystroke.C) Scanner

Scanners are the devices suitable for entering of graphical information into the computer. Some scanners are able to read text so this way of entering textual information will be much quicker than typing.

Scanners are used for quick input of text or images. Recognition of text or images depends on software. It is a very easy input method. Scanners come in the following sizes:

Pens (Scan line at a time)Hand-Held or counter-mounted (Scan bar codes or pictures)Desktop (Scans page at a time)

Types of ScannersI) Graphics ScannersII) Optical character Recognition Reader (OCR)III) Simple character recognitionIV) Full text recognition scanner

D) JoysticksIt is also an input device, used to give input for game play. The actual movement

of the joystick is controlled in much the same way that some mouse pointers use. There are two main types of joysticks available:

I) Digital JoysticksII) Analogue Joysticks

E) Digital CameraPrepared By: Chetan Thapa Magarwww.facebook.com/MeIDoKoXorachetanthapa.wordpress.com[Page 15]

Clock Unit

R e g i s t e r s

Control Unit

Arithmetic Logic Unit

CPU

F) Touchpad etc...3. CPU (Central Processing Unit)

The main unit inside the computer is the CPU. This unit is responsible for all events inside the computer. It controls all internal and external devices, performs arithmetic and logical operations. The CPU is the device that interprets and executes instructions.

The CPU has ability to fetch, decode and execute instruction and transfer information to and from other resources over the computer's main data-transfer path, the bus. It is the chip that functions as the "Brain" of a computer.

The CPU is the composed of several units...

4. Output DevicesOutput Devices are used to get Final Result from the computer. Firstly, Output is

displayed on Monitor then we can printout these outputs on a paper with the help of Printer. The purpose of the output devices is to translate data and information from electrical impulses to human-readable format.

The output device, which is necessary for the computer to display messages to the user, is a monitor. If we want to keep the copy of the work on a paper, we use printers. Plotters are devices that are more suitable for large scale outputs like engineering drawings and high quality graphics.5. Memory Devices (Attached to the System Box/CPU/Casing/Cabinet)

Computer uses memory to hold the programs and data in use by the CPU. Most computers have several type of memory. The main purpose of memory is to store programs and data so that the CPU may access and process it. It also can store partial solutions during the computer run.Mainly, there are two general categories of memory device inside the computer commonly used today.

I) Primary Memory(Main Memory) RAM(Random Access Memory or Read Write Memory)

It is the running workspace of computer. Initially, every task is stored in RAM, when we save these information then information are stored in Secondary Memory (Storage Device). It is also called Volatile Memory because the information is erased when the power is switched off.

RAM is often referred to as main memory or primary storage. It occupies a number of chips connected together. It is used to store programs and data being used by these programs while the computer is on.

ROM (Read Only Memory)

It is the programming chips, where the system information’s entire are kept at the time of manufacture. We can see the information’s of ROM at the time of booting the computer. We can only read the information of ROM. Write/Delete isn’t available on it. The ROM allows us to read only the content of that memory at many times as desired. ROMs are Non-Volatile and Non-Destructive.

When we turn on the computer, the CPU gets its first instructions from the ROM. These instructions are burnt into the chip with the help of special equipment before


the chip is installed inside the computer. User don’t access to the ROM, so they can’t change these instructions.II) Secondary Memory (Auxiliary Memory)

Magnetic Tape Hard Disk Optical Disk


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introduction-and-evolution-of-computer file · Web viewThis process of conversion of raw material into the refined form is nothing but the data ... the Latin word “Computare