Class 11 - Computer || Chapter 1 || Introduction & Evolution of Computer

Chapter 1 

Introduction & Evolution of Computer


Computers are seen everywhere around us, in all spheres of life. May it be the field of education and research, travel and tourism, weather forecasting, social networking, e-commerce or any other, computers have now become an indispensable part of our lives. The manner, in which computers have revolutionized our lives because of their accuracy and speed of performing a job, is truly remarkable. Today no organization can function without a computer. In fact various organizations are trying to become paper free owing to benefits of computers. But the computers of today have evolved over the years from a simple calculating device to the portable high speed computers that we see today. 

Characteristics of Computer 

The characteristics of computer are described below:

▶️ Speed

A computer works with much higher speed andaccuracy compared to humans while performing mathematical calculations. Computers can process millions (1,000,000) of instructions per second. The time taken by computers for their operations is microseconds and nanoseconds.

▶️ Accuracy

Computers perform calculations with 100% accuracy. Errors may occur due to data inconsistency or inaccuracy.

▶️ Diligence

A computer can perform millions of tasks or calculations with the same consistency and accuracy. It doesn’t feel any fatigue or lack of concentration. Its memory also makes it superior to that of human beings.

▶️ Versatility

Versatility refers to the capability of a computer to perform different kinds of works with same accuracy and efficiency.

▶️ Reliability

A computer is reliable as it gives consistent result for similar set of data i.e., if we give same set of input any number of times, we will get the same result.

▶️ Automation

Computer performs all the tasks automatically i.e. it performs tasks without manual intervention.

▶️ Memory

A computer has built-in memory called primary memory where it stores data. Secondary storage are removable devices such as CDs, pen drives, etc., which are also used to store data.

Application Areas of Computer

The application areas of computer are described below:

▶️ Banks:

Banks provide online accounting facility, which includes current balances, deposits, overdrafts, interest charges, shares, and trustee records. ATM machines are making it even easier for customers to deal with banks.

▶️ Engineering: 

Computers are widely used in engineering purpose. One of major areas is CAD (Computer aided design). That provides creation and modification of images.

▶️ Medicine: 

Computers have become important part in hospitals, labs, and dispensaries. The computers are being used in hospitals to keep the record of patients and medicines. It is also used in scanning and diagnosing different diseases. ECG, EEG, Ultrasounds and CT Scans etc., are also done by computerized machines.

▶️ Education: 

The computer provides a tool in the education system known as CBE (Computer Based Education). The computer education is rapidly increasing the graph of number of computer students. It is used to prepare a database about performance of a student and analysis is carried out on this basis.

▶️ Ticketing: 

In today's world one can book air or railway tickets online with the help of computer and internet and could knows all the relevant information. Ticketing system are also applied in bus, hotel and cinemas tickets reservations.

▶️ Defense: 

Computers are largely used in defense. Modern tanks, missiles, weapons etc. Military also employs computerized control systems. Some military areas where a computer has been used are missile control, military communication, military operation and planning.

▶️ Business: 

A computer has high speed of calculation, diligence, accuracy, reliability, or versatility which made it an integrated part in all business organizations. Computers are used in business organizations for payroll calculations, budgeting, sales analysis, financial forecasting, etc.

▶️ Government: 

Computers play an important role in government. Some major fields in this category are budget, sales tax department, income tax department, computerization of voters lists, weather forecasting,etc.

▶️ Desktop publishing: 

We can use computer for desktop publishing, for example: create layout for magazine, newspaper, book, etc. One can create animation and portrait also with the help of different software tools.

▶️  Communication:

Communication means to convey a message, an idea, a picture or speech that is received and understood clearly and correctly by the person for whom it is meant for. Some main areas in this category are email, chatting, ftp, telnet, etc.

Evolution of Computers 

The growth of computer industry started with the need for performing fast calculations. The manual method of computing was slow and prone to errors. So attempts were made to develop faster calculating devices. The journey that started from the first calculating device i.e. Abacus has led us today to extremely high speed calculating devices. Let us first have a look at some early calculating devices and then we will explore various generations of computer.


Abacus was discovered by the Mesopotamians in around 3000 BC. An abacus consisted of beads on movable rods divided into two parts. Addition and multiplication of numbers was done by using the place value of digits of the numbers and position of beads in an abacus. 

Fig: Abacus 

The Chinese further improved on the abacus so that calculations could be done more easily. Even today abacus is considered as an apt tool for young children to do calculations. In an abacus, each row is thought of as a ten’s place. From right to left , row no-1 represents the one’s column and the second column represents ten’s place. The third column represents the hundred’s place and so on. The starting position of the top beads (representing the value of five) is always towards the top wall of the abacus while the lower beads (representing the value of one) will always be pushed towards the lower wall as a starting position. 

Napier’s Logs and Bones

The idea of logarithm was developed by John Napier in 1617. He devised a set of numbering rods known as Napier’s Bones through which both multiplication and division could be performed. These were numbered rods which could perform multiplication of any number by a number in the range of 2-9. There are 10 bones corresponding to the digits 0-9 and there is also a special eleventh bone that is used to represent the multiplier. By placing bones corresponding to the multiplier on the left side and the bones corresponding to the digits of the multiplicand on the right , the product of two numbers can be easily obtained. 

Fig: Napier’s Logs


Blaise Pascal, a French mathematician invented an adding machine in 1642 that was made up of gears and was used for adding numbers quickly. This machine was also called Pascaline and was capable of addition and subtraction along with carry-transfer capability. It worked on clock 

Fig: Pascaline

work mechanism principle. It consisted of various numbered toothed wheels having unique position values. The addition and subtraction operations was performed by controlled rotation of these wheels.

Leibnitz’s Calculator

In 1673 Gottfried Leibnitz, a German mathematician extended the capabilities of the adding machine invented by Pascal to perform multiplication and division as well. The multiplication was done through repeated addition of numbers using a stepped cylinder each with nine teeth of varying lengths. 

Fig: Leibnitz’s Calculator

Jacquard’s Loom

In order to make the cotton weaving process automatic, Joseph Jaquard devised punch cards and used them to control looms in 1801. The entire operation was under a program’s control. Through this historic invention, the concept of storing and retrieving information started.

Fig: Jacquard's Loom 

Difference Engine and Analytical Engine

Charles Babbage, an English mathematician developed a machine called Difference Engine in 1822 which could calculate various mathematical functions, do polynomial evaluation by finite difference and theoretically could also solve differential equations. 

Fig: Difference Engine and Analytical Engine

Thereafter in 1833, he designed the Analytical Engine which later on proved to be the basis of modern computer. This machine could perform all the four arithmetic operations as well as comparison. It included the concept of central processor, memory storage and input-output devices. Even the stored information could be modified. Although the analytical engine was never built that time but Babbage established the basic principles on which today’s modern computers work.

Both these great inventions earned him the title of Father of Modern Computers.

Mark 1 

In 1944 Prof Howard Aiken in collaboration with IBM constructed an electromechanical computer named Mark 1 which could multiply two 10 digit numbers in 5 seconds. This machine was based on the concept of Babbage’s Analytical engine and was the first operational general purpose computer which could execute preprogrammed instructions automatically without any human intervention. 

Fig: Mark 1

In 1945, Dr. John Von Neumann proposed the concept of a stored program computer. As per this concept the program and data could be stored in the same memory unit. The basic architecture of the Von Neumann computer is shown in the figure below

Fig: Von Neumann Computer 

According to Von Neumann architecture, the processor executes instructions stored in the memory of the computer. Since there is only one communication channel, the processor at a time can either fetch data or an instruction. That means at one point of time either the data or an instruction can be picked (fetched) from the storage unit for execution by the processor. Hence execution takes place in sequential manner. This limitation of Von Neumann Computer is known as Von Neumann bottleneck. EDVAC (Electronic Discrete Variable Automatic Computer) was the first stored program computer developed in 1952. After the invention of first electronic computer ENIAC (Electronic Numerical Integrator and Calculator) in 1946, the computer technology improved tremendously and at very fast pace. 

Generation of Computers 

Growth in the computer industry is determined by the development in technology. Each phase/generation of computer development is characterized by one or more hardware/software developments that distinctly improved the performance of the computers of that generation. Based on various stages of development, computers can be divided into different generations. 

The First Generation (1942-1955) 

The first generation computers used the concept of ‘stored program’ and were characterized by vacuum tubes. A vacuum tube is a delicate glass device that can control and amplify electronic signals. The first generation computers were made using thousands of vacuum tubes and were the fastest calculating devices of their time. These computers were very large in size, consumed lot of electricity and generated lot of heat. UNIVAC 1 was the first electronic computer of this generation and was used for business applications. 

Salient features of First generation computers: 

▶️ Used vacuum tubes to control and amplify electronic signals 

▶️ Huge computers that occupied lot of space 

▶️ High electricity consumption and high heat generation 

▶️ Were unreliable since they were prone to frequent hardware failures 

▶️ Commercial production was difficult 

▶️ They were very costly and required constant maintenance 

▶️ Continuous air conditioning was required 

▶️ Programming was done in machine language although assembly language also started at the end of this generation Example : ENIAC , EDVAC , UNIVAC 1 

Note: ENIAC weighed about 27 tons, was of the size 8 feet × 100 feet × 3 feet and consumed around 150 watts of power.

The Second Generation (1955–1964)

The second generation computers were characterized by transistors. A transistor is a solid state semiconductor device that revolutionized the electronic industry. Transistors were smaller, highly reliable, consumed less electricity and generated less heat. Also magnetic core memories were developed during this generation. These are tiny ferrite rings that can be magnetized in either clockwise or anticlockwise direction so as to represent binary 1 or binary 0. Magnetic cores were used as primary memories. Later magnetic disks also came into existence and were used as secondary storage devices. All these new developments – transistors, magnetic core memory and magnetic disk storage devices made the computers more powerful and reliable. This further led to the existence of operating systems. Programming languages like FORTRAN, COBOL, Algol etc. also developed. Commercial applications of the computer increased and now the computers were used in business and industries for applications like payroll, employee management, inventory control etc. IBM 1401 and IBM 1620 were popular computers of this generation. 

Salient Features of Second generation computers: 

▶️ Use transistor based technology 

▶️ Were smaller and less expensive as compared to first generation 

▶️ Consumed less electricity and emitted less heat 

▶️ Magnetic core memories and magnetic disks were used as primary and secondary storage respectively 

▶️ First operating system developed 

▶️ Programming in assembly language and in the later part high level languages were used 

▶️ Wider commercial use but commercial production was still difficult 

▶️ They also required constant air-conditioning. 

Examples: IBM 1401, IBM 1620, UNIVAC 1108

The Third Generation (1964-1975) 

In 1964, the Integrated Circuits or ICs or chips revolutionized the electronic industry and started the third generation of computers. An IC is a small silicon chip or wafer made up of extremely purified silicon crystals. It has numerous transistors, capacitors, resistors and other elements of an electronic circuit. A small scale integration (SSI) chip used to have about 10 transistors on a single chip and a medium scale integration (MSI) chip had about 100 transistors per chip. The size of memories also increased. Various mainframe computers and minicomputers were developed during this generation. Even operating systems with multitasking and multiprogramming features were developed. Since ICs made the computers highly reliable, relatively inexpensive and faster, computers these days were found in areas of education, small businesses and offices along with industrial and business applications. IBM 360 was a very popular third generation computer.

Salient Features of Third Generation computers: 

▶️ Used integrated circuits 

▶️ Computers were smaller , faster and more reliable 

▶️ Low power consumption and less emission of heat as compared to previous generations 

Examples: IBM 360 series, Honeywell 6000 series

The Fourth Generation (1975 onwards) 

In this generation Large Scale Integration (LSI) and Very Large scale integration (VLSI) technology was used by which up to 300,000 transistors were used on a single chip. Thus integration of complete CPU on a single chip was achieved in 1971 and was named microprocessor which marked the fourth generation of computers. The computers based on microprocessor technology had faster accessing and processing speeds. In addition to this the increased memory capacity further made the computers more powerful and also more efficient operating systems were developed for these computers. New concepts of microprogramming, application software, databases, virtual memory etc were developed and used. The computers that we use today belong to this generation. These portable computers can be carried from one place to another owing to their compact size. They are much more accurate. Even memory sizes have become phenomenal. Commercial production of these computers is easier and they are the least expensive, compared to the earlier generation computers. Also computer networks starting coming up during this generation. It is today one of the most popular means to interact and communicate with people. 

Salient features of Fourth generation Computers

▶️ ICs with LSI and VLSI technology 

▶️ Microprocessors developed 

▶️ Portable computers developed 

▶️ Networking and data communication became popular

▶️Different types of secondary memory with high storage capacity and fast access developed 

▶️ Very reliable ,powerful and small in size 

▶️ Negligible power consumption and heat generation 

▶️ Very less production cost 

Fifth Generation Computers 

Fifth Generation computers are still under development. This generation is based on the concept of artificial intelligence. In simple terms the computers of this generation are supposed to behave like humans. The principles of parallel processing (many processors are grouped together) and superconductivity are being used to develop devices that respond to human languages and will have the ability to apply previously gained knowledge to execute a task. They will let them make decisions of their own to execute a task. Some applications like voice recognition, visual recognition are a step in this very direction. 

Salient features of fifth generation computers: 

▶️ Parallel Processing 

▶️ Superconductivity 

▶️ Artificial Intelligence

Functional Components of a Computer 

The computer is the combination of hardware and software. Hardware are the physical components of a computer like motherboard, memory devices, monitor, keyboard etc. while software is the set of programs or instructions. Both hardware and software together make the computer system function. Let us first have a look at the functional components of a computer. Every task given to a computer follows an Input- Process- Output Cycle (IPO cycle). It needs certain input, processes that input and produces the desired output. The input unit takes the input, the central processing unit does the processing of data and the output unit produces the output. The memory unit holds the data and instructions during the processing.

Input Unit

The input unit consists of input devices that are attached to the computer. These devices take input and convert it into binary language that the computer understands. Some of the common input devices are keyboard, mouse, joystick, scanner etc. 

Central Processing Unit (CPU) 

Once the information is entered into the computer by the input device, the processor processes it. The CPU is called the brain of the computer because it is the control centre of the computer. As the CPU is located on a small chip, it is also called the microprocessor. It first fetches instructions from memory and then interprets them so as to know what is to be done. If required, data is fetched from memory or input device. Thereafter CPU executes or performs the required computation and then either stores the output or displays on the output device. The CPU has three main components which are responsible for different functions – Arithmetic Logic Unit (ALU) , Control Unit (CU) and Memory registers. 

Arithmetic and Logic Unit (ALU)

The ALU, as its name suggests performs mathematical calculations and takes logical decisions. Arithmetic calculations include addition, subtraction, multiplication and division. Logical decisions involve comparison of two data items to see which one is larger or smaller or equal. 

Control Unit 

The Control unit coordinates and controls the data flow in and out of CPU and also controls all the operations of ALU, memory registers and also input/output units. It is also responsible for carrying out all the instructions stored in the program. It decodes the fetched instruction, interprets (understands) it and sends control signals to input/output devices until the required operation is done properly by ALU and memory. 

Memory Registers 

A register is a temporary unit of memory in the CPU. These receive data/information and then this data/information is held in them as per the requirement. Registers can be of different sizes(16 bit , 32 bit , 64 bit and so on) and each register inside the CPU has a specific function like storing data, storing an instruction, storing address of a location in memory etc. The user registers can be used by an assembly language programmer for storing operands, intermediate results etc. Accumulator (ACC) is the main register in the ALU and contains one of the operands of an operation to be performed in the ALU. 


Memory attached to the CPU is used for storage of data and instructions and is called internal memory. During processing, it is the internal memory that holds the data. The internal memory is divided into many storage locations, each of which can store data or instructions. Each memory location is of the same size and has an address. With the help of the address, the computer can find any data easily without having to search the entire memory. The internal memory is also called the Primary memory or Main memory. When the task is performed, the CU makes the space available for storing data and instructions, thereafter the memory is cleared and the memory space is then available for the next task. The time of access of data is independent of its location in memory, therefore this memory is also called Random Access memory (RAM). Primary memory is volatile in nature. That means when the power is switched off, the data stored in this memory is permanently erased. That is why secondary memory is needed to store data and information permanently for later use. Some of the examples of secondary storage devices are hard disk, compact disks, pen drives etc. 

Output Unit

The output unit consists of output devices that are attached with the computer. It converts the binary data coming from CPU to human understandable from. The common output devices are monitor, printer, plotter etc.

History of Computer in Nepal

The history of computer in Nepal is not that old since Nepal has not given any contribution in the development of evolution of computer. It was in 2028 B.S. when HMG brought IBM 1401 (a Second Generation computer) on rent for Rs. 1 lakhs and 25 thousand per month to process census data. Later the computer was bought by National Computer Center (NCC). In 2038 B.S., a fourth generation computer was imported with the aid of UNDP and UNFPA from England for 20 lakhs US dollars. Its name was ICL 2950/10. This computer had 64 terminals and it is kept in museum now.

At that time British Government helped to develop manpower of NCC. In the meantime Nepalese students went to India, Thailand and USA for the computer education themselves. In 2039 B.S., microcomputers such as Apple, Vector, Sins, etc were imported by private companies and individuals. Many private companies like Computer Consultancy (CC), Management Information Processing System (MIPS), Data System International (DSI), etc were established. Such private companies started selling computers and training people in other to produce manpower in Nepal itself.

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