Fundamental of Computer_BSC

Computer: - Computer is an electronic data processing device, which accepts and store data input, processes the data input and generates the output in a required format. All physical parts of the computer that we can touch or feel are known as hardware. Example keyboard, mouse, monitor etc. A group of program that a computer uses to perform specific task is called software. Example Mozilla Firefox, MS Paint etc.

How does a computer work: - Computer transfer input (data) into required output (information). During this transformation, a computer functions in the following manner:

The computer accepts input:-The process of entering data and program in to the computer system. An input device includes keyboard, mouse, scanner etc. Input includes words and symbols in a document, number for calculation, instruction for completing a process, picture and so on.

The computer stores data:-The process of saving data and instruction permanently is known as storage. Storage device includes Hard disk, Tapes, CD/DVDs, pen drive, floppy disk etc.

The computer processing the data: - The task of performing operation like arithmetic and logical operation is called processing.

The computer produces output: - The process of producing results from the data for getting useful information. Output device includes printer, monitor, speaker etc.

The Computer System: - A computer contains different hardware components that interact with each other to perform the task. Major hardware component in computer system are Central Processing Unit, Input Unit, Output Unit, Primary memory, secondary storage and communication devices.

Central processing unit: - The ALU and CU of a computer system are jointly known as central processing unit. CPU is the brain of any computer that takes all major decisions, makes all sorts of calculation and directs different parts of the computer function by activating and controlling the operation.

CPU consists of following components

o   Arithmetic and logic Unit (ALU)

o   Control Unit(CU)

o   Registers

ALU perform fundamental mathematical operation consisting of addition, subtraction, multiplication and division. It also performs logical operation that consists of comparisons like equal to, less than, greater than etc.

Control Unit (CU) coordinates and controls the operation of a computer system. It controls the activities between memory and ALU and between CPU and input/output devices.

Registers are high speed storage areas in the CPU that store very small amount of data and instruction for short period of time during calculation.

Input unit:-A device is used to feed data into a computer is called input devices or input unit. It sends data into the CPU or RAM. Example keyboard, mouse, scanner, touch screen, light pen etc.

Output unit: - Any device that receives and displays output from a computer is called an output device or output unit. Example monitor, printer, plotters, speaker.

Primary memory: - A memory that is accessible directly by the processing unit is called primary memory. CPU can read data directly from the primary memory and can also write data directly to it. We can store and retrieve data much faster with primary memory. The rate of fetching data from this memory is of the order 50 nanosecond/byte. Example RAM, ROM, Cache memory.

Secondary memory: - The memory or storage devices that are not directly accessible to CPU are called secondary memory. It is used to store large volume of data on permanent base that can be partially transferred to primary storage, whenever required for processing. Example floppy disk, Hard disk, CD/DVD, flash memory, Sequential Access Device, Direct Access Device, Magnetic Disk etc. This type of memory is located outside the computer system.

Communication devices: Hardware devices that support data transmission and reception across a telecommunications system are called communication devices. This device includes MODEM, Multiplexer, Network Interface Card etc.

Difference between primary memory and secondary memory

Primary memory	Secondary memory
Normally volatile in nature. This means content of primary memory is lost when power is lost.	Normally non-volatile in nature. This means content of secondary memory can be retailed after power loss.
Used to store program instruction and data that are used during current execution	Used to hold programs and all data needed by the program
Faster than secondary memory	slower than primary memory
Much more expensive than secondary memory	Lot of cheaper compared to primary memory
Accessible to CPU directly	Cannot be accesses by CPU directly.
example RAM, ROM,  Cache memory	example Hard disk, flash memory, DS/DVDs

How CPU Works: - Set of micro-operations needed to complete an operation is called instruction cycle. Basically a machine cycle consists of following micro-operations

Fetch: - Control units read the instruction to be executed form memory and load it into the register called instruction register.

Decode: - After reading the instruction control unit identifies the operation to be performed, identifies the operands and reads the operands form memory.

Execute: - Once the operation and operands are available.  ALU performs the specified operands and put the result in any one of the register.

Store: - If the result produced by ALU needs to be stored in memory then this operation is needed, this operation is no need for all instructions.

Factor affecting the performance of the CPU include:

·        Clock Speed: The time needed to change the state of a transistor is called clock speed. It is measured in megahertz (millions of cycles/sec) and gigahertz (billions of cycles/second). Higher the clock speed, faster the CPU will be.

·        Word length: The number of bits (0s and 1s) that can be processed by the CPU at any one time. Higher the world length, faster the CPU will be.

·        Bus Width: The size of the physical path through which the data and instructions travel as electrical impulses on s computer chip. Larger the width, faster the CPU will be.

·        Line width: The distance between transistors is known as line width. The smaller the line width, the faster will be the chip. Smaller the line width, faster the CPU will be.

Characteristics of computers

High-speed:-Computer is a very high speed electronic device. It can perform any calculation in a few milliseconds. Computer can perform complex calculation at a high speed that human being may not be able to do. The following terms are used to describe the speed of computer.

Unit of Time	Parts of Second
Millisecond(ms)	1/1000 of second
Microsecond(us)	1/1000000 of second
Nanosecond(ns)	1/1000000000 of second
Picoseconds(ps)	1/1000000000000 of second

Accuracy: - Even though the computer has great speed, computers are very accurate. Computer acts upon the data as per given instruction and then gives the desired output. So accuracy means if the data, instruction is correct and reliable then the output produced by the computer is also correct and reliable. This is known as garbage in garbage out (GIGO).

Storage capacity:-The physical space inside the computer where we can store huge amount of data is called storage. Example hard disk, CDROM, DVD-ROMs, magnetic tape etc.

The storage capacity for a computer is measured in

Units	Meaning
0 or 1	1 Bit
4 Bits	1 Nibble
8 Bits	1 Byte
1024 bytes	1 Kilobyte (KB)
1024 Kilobytes	1 Megabyte (MB)
1024 Megabyte	1 Gigabyte (GB)
1024 Gigabyte	1 Terabyte (TB)
1024 Terabyte	1 Petabyte (EB)
1024 Petabyte	1 Exabyte
1024 Exabyte	1 Zetabyte (ZB)
1024 Zetabyte	1 Yottabyte (YB)

Diligence: -A computer is capable of performing the task continuously in the same speed for a long time. The characteristic of computer makes it useful for repetitive job like process control and quality control.

Versatility: -Computers are versatile machine. Computers are being used in different areas for different propose like in office, home, banks etc. the capabilities of computer to perform different task and has a wide range of areas depending upon different program used in it known as versatility.

Automatic: - Computers are automatic machine because one started on a job they carry out the job without any human intervention until it is finished.

Reliability-A computer is a reliable machine. Modern electronic components have long lives. Computers are design to make maintenance easy.

Limitation of computer

1.      No self-Intelligence: - Computer can do very complex and dangerous task which are impossible for human being. It works according to the give instruction only. It does not have any intelligence of its own.

2.      No thinking and Decision making power(IQ): - It cannot take any decision of its own, it does only those tasks which are already instructed to it in the form of program. It is we to decide what we want to do and in what sequences.

3.      No feeling: - A computer cannot feel anything as human. It does not have feelings or emotion, taste, knowledge and experience.  This it does not get tired even after long hours of works.

4.      No learning power: - Computer has no learning power. Once we give instruction to a computer how to perform a task. It cannot perform the same task if we do not give it any instruction for the next time.

History of Computer

Abacus: - It was derived from Latin word ABAX. Abacus consists of a rectangular frame carrying number of rods and coils along with beads. It is divide into two parts:- Sliding the beads towards or away from the central bar, the calculation was performed .

Napier's Bone:-It was invented by John Napier in 1617 A.D. In 1614 he published the first table of logarithm in the book called Rabdologia which was much helpful in simplifying the multiplication of large number. In 1617, he invented a small instrument constructed of ten rods called Napis Bone which were multiplication table inscribed on strips of wood or bone.

Slide rule: - In 1620 AD, slide rule was discovered by William Aughtred, an English mathematician of U.K. which is an analog device. It uses the principle of logarithm. It is easy to find the product, quotient or any other functions simply viewing on the scales. It was used by engineers for multiplication and division.

Pascal's Machine:-in 1642, the French scientist Blaise Pascal invented a first true mechanical calculating device called Pascaline. Pascaline consists of toothed wheels or gears with each wheel or gear having digits 0 through 9 engraved on it. The machine had capacity to add, subtract 8-bit number. The basic principle of his calculator is still used in water meters and modern day odometers.

Leibnitz's calculation machine: - In 1671, a German mathematician Gottfried Wilhem Von Leibniz invented a calculating machine called Leibniz Calculation Machine. The stepped Recknoer could perform addition, subtraction, multiplication and division.  Although the stepped reckoner employed the decimal umber system (each drum had 0 flutes), Leibniz was the first to advocate the use of binary number system which is fundamental to the operation of modern computers.

Charles Babbage:- Charles Babbage , the professor of mathematician at Cambridge University invented different engines in 1823. In 1833, he invented analytical engine. He is known as the father of computer science. he has a concept of using digital in his machine. The Engine would be able to computer tables of numbers, such as logarithm table.

Babbage realized that pouched paper could be employed as a storage mechanism, holding computer number of future reference. Because of the connection to the Jacquard's Loom, Babbage called the two main parts of his analytical Engine the "Store and the Mill".

Lady Augusta ADA Lovelace:- She was the daughter of great poet baryon. She gave the idea to use binary number to Charles Babbage in his analytical machine. She was known as the first programmer in the computer history. ADA invented the subroutine as was the first to recognize the importance of looping.

Howard Mark I:- Mark-I is an electromechanically operated computer made by Professor Howard Aiken in 1937. This machine used punched cards which Charles Babbage also used for his Analytical Engine. This machine was 51 feet long, 3 feet wide and 8 feet height. It has 18000 Vacuum tubes, 750000 parts and cable connection about 500 miles long. It took 1 second for 3 mathematical addition and 4.5 seconds for multiplication.

Dr. John Von Neumann: - He gave a concept that the program can be stored and these stored programs can be used in future processing and instruction, which is called stored program concept. The computer can work in two state 0 and 1 i.e. binary system.

ENIAC:-It was developed by Professor J.P Eckert and John W. Mauchly. It had the storage concept developed in it. It is an electronic calculator. It is very huge machine. It has various switches to feed the instruction. It can perform multiplication in 3000th of a second. It has 18,000 vacuum tube and 7000 registers.

EDSAC:-It was invented by Maurice Wilkes at Cambridge University in 1949. It used 39000 vacuum tubes, 30 KV of electricity power. In EDSAC, an additional operation took 1500 microseconds and multiplication operation took 4000 microseconds.

EDVAC: - In 1952, John Mauchlyu and J.P. Eckert and John Von Neumann invented EDVAC. It was used to stored data as well as instruction. It used 400 vacuum tubes and 1000 crystal diodes, the EDVAC used the stored program concept in its design.

 
UNIVAC-1:- John W. Mauchly and J.P. Eckert got encouraged and opened owned company started to design UNIVAC-1. UNIVAC-II was commercial purpose machine and used in Census Bureau of Statistics. Later IBM Company developed better and cheaper computer series in 1945-55, since then IBM is one of the leading computer manufacturing company.

Generation of computers: - Each generation of computer is characterized by the major technological development that fundamentally changed the wat computer operates, resulting in increasingly smaller, cheaper and more powerful and meot efficient and reliable devices. The computesr are broadly classified into five different generations. They are

First generation computer (1946-1959):- It used Vacuum tubes for memory device. Example ENIAC, MARK-I and EDVAC.

Advantage

v  Vacuum tubes were the only electronic component available during those days

v  vacuum tube technology made possible the advent of electronic digital computers

v  These computers were the fastest calculating device of their time. they could perform computations in milliseconds

Disadvantages

v  Too bulky in size so not portable

v  very unreliable because prone to frequent hardware failures

v  Thousands of vacuum tubes that were used emitted large amount of heat and burnt out frequently. So air conditioning is required.

v  Manual assemble of individual components into functioning unit is required.

v  Commercial production was difficult and costly so limited to commercial uses.

Second generation computer (1959-1965): - It uses transistors. One transistor could replace with 1000 vacuum tubes. Mark-1 has 18000 vacuum tubes and can be replaced by 18 transistors. Example IBM 1401, ICL 1300.

Advantages

v  Smaller in size as compared to first generation computers and thus have better portability.

v  More reliable that first generation computer because less prone to hardware failures

v  Generates less heat and hence can be operated for longer times.

v  These computers were able to reduce computational times from milliseconds to microseconds

v  Wider commercial use than first generation computers

Disadvantage

v  Air condition is rewired

v  Manual assembly of individual components into a functional unit was required.

Third generation computer (1965-1971):- It used IC (Intergrated Circuit) as memory device. Programming languages such as FORTRAN, COBOL etc are the features of 3rd generation computer. Example BM360, ICl-1901 etc

Advantages

v  Smaller in size as compared to previous generation computers and increases portability

v  More reliable and generates less heat that second generation computers.

v  These computers were able to reduce computational times form microseconds to nanoseconds.

v  Totally general purpose. Widely used for various commercial applications all over the world

v  less power required than previous generation computers

v  Manual assembly of individual components into a functional unit not required. So human labor and cost involved at assembly stage reduced drastically

v  Commercial production was easier and cheaper.

Disadvantages

v  Air conditioning required in many cases

v  Highly sophisticated technology required for the manufacture of IC chips

Fourth Generation computer (1971-1980) :-It used microchip (VLSI) as memory device. Example Intel 4004, Macintosh Apple, IBM-PC etc.

Advantages

v  Smallest in size because of high component density and hence are portable

v  Very reliable and heat generated is negligible

v  No air conditioning is required in most cases

v  Much faster in computation than previous generation

v  Hardware failure is negligible and hence minimal maintenance is required.

v  Totally general purpose and minimal labor and cost involved at assembly stage.

v  cheapest among all generations

Disadvantages

v  Highly sophisticated technology required for the manufacture of LSI chips.

Fifth generation computer: - It is going to use Biochip. Biochips will use materials like gallium that have much more conductivity than silicon. It will be able to understand natural language and will have thinking power called artificial Intelligence (AI)

Features

v  BIO chip will be used as main component in 5th generation

v  They will have artificial intelligence.

v  They will provide natural computer interface.

v  They will use multi/parallel processor system.

Classification of computes

On the basis of working principle: - On the basis of working principle, computers are categorized into three types-

Analog Computer: -A computer in which problem variables are represented as continuous variable physical quantities such as temperature, electrical, mechanical or hydraulic quantities. Presley is an example of analog computer.

Characteristic

·        Analog computer measures the continuous physical variations such as pressure, temperature, voltage etc

·        It generates analog signals

·        It has very low accuracy

·        I has high cost

·        It is used for special purpose

·        Re-programmed is not possible

·        E.g. Speedometer, Seismograph

Digital computer: - A digital computer is an electronic computing machine that uses the binary digits (bits) 0 and 1 to represent all forms of information in digital form.

Characteristic

·        Digital computer processes discrete data such as number, letters etc.

·        It generates digital signal

·        It has high accuracy

·        It is used for general purpose

·        Re-programmed can be possible

·        E.g. IBM PC, IBM Compatible, Apple/Macintosh

Hybrid computer: - Computer that contains the features of analog computers is capable of inputting and outputting in both analog and digital signal. Example FMC, EICS.

Characteristic: -

·        Can process both continuous and digital data

·        It has capacity to convert one type of data into another

·        These are special purpose machine.

·        These computers normally have high cost

On the basis of power and size

Super computer:-Supercomputer is one of the fastest computer current available. Super computers are very expensive and are employed for specialized application that required immense amount of mathematical calculation. Example weather forecasting, scientific simulation, animated graphics, fluids dynamics calculation, nuclear emery research, electronic design and analysis of geological data. Example Cray-1, ETA10, Y-MP/C90 etc

Mainframe computers:-It is a general purpose computer designed for large scale data processing. This machine can handle word length of 32 to 64 bits having an execution speed of 100 to 200 MIPS hand having the memory size of 256 to 512 megabits (MB). Memory access time is of 123 nanoseconds; this computer can enter 100 to 200 data operator worked at the same time with a single CPU. Example IBM-1401, IBM-4300 seried, IC2950/10  etc.

Minicomputer: -Mimi Computer is a general purpose computer which is comparatively small and less expensive than a mainframe computer. It has slower operating speed, smaller vacuum storage, limited hardware and lesser memory capacity compared to a install and operated Mini computers are relatively easy to install and operate in a multi-terminal device,. These have a memory of 64 to 256 MB; access time being 75 to 100 nanoseconds an can handle 16 to 32 bit word length. Example IBM AS1400, IBM/B60, HP-900, PDP-II, VAX-11/780, plesley etc.

Workstation: - Work station is a computer used for engineering application (CAD/CAM). Desktop publishing, software development which require a moderate amount of computing power and relatively high quality graphics capabilities.

Personal computers: - A personal computer is a single user oriented and general purpose micro computer processing system that can execute the program instruction to perform a wide variety task. a person computer contains a monitor keyboard, mouse etc. Several high level languages can be used in personal computer, popular operating system such as MSDOS, Microsoft Windows, Windows NT, Linux, and UNIX are used in this type of computer system.

Application areas of computers

1.      Office: - Important work performed in office such as preparation of letters, reports, copy of advertisement, publicity, contract, forms, notes etc are efficiently performed by computer. Computer helps the user ion preparing, storing and retrieving information.

2.      Desktop publishing system: -All magazines, newspaper, books, comics are produced using computers. Software such as word-processing is used for text typing, dia for drawing, figure etc.

3.      Data Analysis: Software such as spreadsheet can be used to tabulate result, calculate number of students, average marks. One can prepare product sales, profit, invest from an organization. Computers are widely used for statistical data analysis.

4.      Computer Aided manufacturing (CAM): Computer is used to control the production of certain engineering products, chemical products etc. Example in a mechanical industry, designer used Auto CAD for designing the machines and machine parts. CAM system is used to automate the production such as quality control, measuring the size of the item during production, measuring packaging the item after production and many more.

5.      Graphics: Computers are being used to draw drawing, graphics and picture. Graphics packages such as MS paint, Adobe Photoshop, Coral Draw etc. are used for two and three dimension drawing.

6.      Database Management: Computers are extensively used to store and retrieve information. File are now stored in magnetic memory. There is no need of paper to store the information. Database management system not only stores the information but also does data analysis of information popular database management software are ORACLE, Sybase, SQL, MS ACCESS etc.

7.      Project management: A project management project used to plan, schedule and control man power, material and other resource needed to complete the project in schedule time period at a reasonable cost. Computer are used to plan, schedule and perform the detail analysis of the work done, in case of project delay, computer helps to increase the speed id time for completion.

8.      Communication: Computers are extensively used in sending and receiving information. The information transfer may take place either between two points or throughout a computer network that connects a number of computers or workstations. Different communication services such as Electronic mail (e-mail), teleconferencing or video conferencing, internet phone, bulletin board system (BBS), chatting, online banking, satellite communicant etc. are used for communication.

9.      Education: In educational institutions, computers are used as a teaching aid, information resource and research tools. When a computer is used as a teaching tool, it is referred to as Computer Assisted instructions (CAI). Internet technology provides several educational materials, online lectures and tutorials for students.

10.   Medical field: Computer is widely used in hospital to help doctors in diagnosis, getting information on patients, diseases, treatment, drugs etc. They are also used in administration and in keeping patient records.

11.   Reservation System: Computers store all information in connection with tickets reservation such as train /bus/aero plane number, station, distance, number of seats.