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ComputerComputer FundamentalFundamental

Computer Fundamental

Introduction of Computer:The term of computer word from the Greek word “COMPUTE” which means to

calculate. The term of computer word stands for Common Oriented Machine Popular Used for Trade Education Research. Actually, computer is an electronic machine which accepts the Input data, stores a large amount of data in a small place and does the Arithmetical and Logical operations rapidly and gives the data (Output) in a desired format. In the year 1822 Charles Babbage a mathematician of Cambridge University developed a new machine known as COMPUTER. So he was regarded as father of computer.

Now a day’s computers are highly used in various sectors because to save time, Quick performance, Avoid mistakes and stores data in a small place for longer period.

A computer has basically four components that are keyboard, Mouse, C.P.U., and Monitor. By those four components are Input Unit, Process Unit and Output Unit. Key Board and Mouse come under Input Unit. By using two components a user can give any type of data to the computer. Then comes C.P.U. (Central Processing Unit) it means by using this C.P.U. a computer does all type of operation like Arithmetic, Logic and control operation and gives the output. Then come Output Unit. Under this category basically Monitor and Printer is used. By using these two components a computer displays the output data. So above all there are four Units make a computer as a complete machine.

The activity of processing data using a computer is called data processing. Data processing consists of three sub activities: capturing input data, manipulating the data and managing the output results. Data is raw material used as input the data processing and information is the processed data obtained as the output of data processing. Parts of a computer system:

A computer is an electronic device that processes data, converting it into information that is useful to people. A computer system consists of four parts hardware, software, one or more user and data. Users:

People are the computer operators also known as users.Data:

Any type of instruction, information or command used by the user is known as data. The data become various in types like alphabetic data, logical data, and arithmetic data, when a user uses any type of data in a computer it must be a series of logical steps. Then the computer understands and does the operation required by the user. A file that the user can open and use is often called a document. Need of Computer:

Now a computer is highly used in various sector because to save the time, to avoid mistake, quickly performance, store data easily in a small place and for better performance.Feature of Computer:

In this day’s computer is essential part of the life. Now a day’s computers have 8 mini characteristics. This changes the life style due to the following fracture.

Speed Accuracy Memory Automation Versatility Diligence No IQ like slave No fillings

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Speed:A computer is very fast devices. It can process instruction in fraction. So performance of

computer depends upon in speed. In a few second a computer Can perform the task that a human being can ‘t does in a year or more. The speed of the computer is divided in 4categories that is as follow.

1 millisecond =1/1000 sec =10-3

1Micro second =1/106sec =10-6

1Nino second =1/109sec =10-9

1Pico second =1/1012sec =10-12.

Accuracy: It is a most accurate machine in this world. The accuracy of computer is constantly high it

depends upon the data given by the user. If a user inputs the data accurately as per required. Memory:

A computer can remember what even we tell it to store. Every piece of data may be store in a computer memory, as long we desired it. It has large memory power. And the memory of computer can define as fallows: - 1 or 0 =1 bit 8 bits = 1 Byte 4 Bits = 1 Nibble 1024 Byte =1 kilo Byte 1024 K.B = 1 Mega Byte 1024 M.B = 1 Gaga Byte 1024 G.B = 1 Tara Byte Automation:

Thought the data a computer can perform all types of task in a few second. Once you input data computer dose all types of operation automatically to give the output data. It does not require any types and human help during the operation.Versatility:

Computer can perform any types of task in every few second. And also it is a multi-tasking machine. We can do two or three types of works in a single time. But it always needs a prepare data or the data must be a series of logical steps to perform. So versatility is one most wonderful character sticks of computer.Diligence:

Human being generally gets tired after a couple of hours of work, and makes the mistakes. But computers simply don’t get bored and can perform the same operation repeatedly over any long of time. Move over the computer will take the since to do the first calculation as the thousand calculation.No feeling:

A computer has no felling because it has no life. It is only a machine. We the human being can choose what is bad of or what is good. But computer never do things this way. When a user gives wrong data, it takes and when input accurate data if it receives. He never thought what is perfect or not. So, it has no feeling.No IQ:

A computer is a magical device but it’ IQ is zero. A computer cannot take its own decision in this day. It works like a slave. Once you order some things it performs. Otherwise it can’t these are the character sticks of a computer.




Evolution or History of computer: Necessity is mother of invention so human beings invent computer. At fast computer were

invented because of human being’s search for fast time accurate calculating device.

History of computer is divided into three type that as fallows Dark Age (before 1500 AD)

Middle Age (1500-1900 AD)Modern Age (1900 onwards)

Dark Age:IN this age human beings are living in jungles. They don’t know any things after few years

they do exchange product to purchase and thing. So that ere is known as Dark Age of human society. Roman number system was introduced in this age. In this age ABACUS (Abundant beads addition and Calculation Utility System) was introduce. Middle Age:

In this generation, lots of things have been developed. A new year has been come through in this century. In the year 1617 john Napier discovered logarithms. In 1642 Blaise Pascal designs a first mechanical calculating (adding) machine called Pascaline for addition and substation. In the year 1671 Baron Gottfried Wilhelm Von Leventiz of Germany developed first calculator machine to multiplied and divide.

In the year 1822 a leady mathematician known as leady Ada Lovelace of Cambridge University developed a program to build a machine. In the same year by adapting that program a mathematician of same University known as Charles Babbage (Father of modern digital computers) build a machine known as “Deferential machine”. In 1842, Babbage came out with new idea of Analytical Engine which was intended to be completely automatic. Modern Age:

Later in the year 1933 again he designed a machine called Analytic Machine known as complete computer. So, he was regarded father of computer.Mark-1 computer:

The Mark-1 computer was the fast fully automatic calculating machine designed by Howard A. Aiken of Harvard University, in collaboration with IBM (International Business Machines) Corporation in 1937-44. It was an electro mechanical device, since both mechanical and electronic components were used in its design. Atansoff-Berry Computer:

The Atansoff-Berry Computer is an electronic device. It was developed by Dr. John Atansoff to solve certain mathematical educations in 1939-42. It used 45 vacuum tubes for internal logic and capacitors for storages.ENIAC:

In 1943-46 ENIAC (Electronic Numerical Integrator and Calculator) developed computers which have 18000 vacuum tubes, 70000 resisters, 10000 capacities, 6000switch took 30 tones consumed 15000 square foot 130 Kilo watt current. It was the first all electronic computer. It was constructed at the Moore School of Engineering of the University of Pennsylvania. It was design by Professors J. Presper Eckert and John Mauchly. EDVAC:

The EDVAC (Electronic Discrete Variable Automatic Computer) was developed in 1946-52 by John von Neumann. The basic idea behind this concept is that a sequence of instructions, as well as data, can be stored in the memory of the computer for automatically directing the flow of operations. It was designed on stored program concept.




EDSAC:The EDSAC (Electronic Delay Storage Automatic Calculator) was developed in 1047-49 by a

group of scientists, headed by Professor Maurice Wilkes, at the Cambridge University Mathematical Laboratory. UNIVAC:

The UNIVAC (Universal Automatic Computer) was introduced in 1951 and was used for 10 years. It was the first digital computer which was not “one of a kind”. In 1952, the International Business Machine (IBM) Corporation introduced the 701 commercial computers. In 1953, IBM produced the IBM-650.

Generation of Computer:“Generation” in computer talks is a step-in technology. It provides a framework for the

growth of the computer industry. Today there are several millions of computers in use. The evolution of computer has been rapid developments in electronic technology by this reason the generation of computer has been classified in to six types. That is as fallows. 1st Generation (1942-1955):

In this generation thousands vacuum tubes are used and they were too bulky in size, requiring large space for installation. A vacuum tube was a fragile glass device, which used filaments as a source of electronics and control & amplify electronic signal. Vacuum device was only high speed electronic switching device. In these computer thousands of individual components had to assemble manually by hand into functioning circuits. So computer is difficult to programming. In this generation machine label language (Binary code) was used.

Ex: - ENIAC, EDVAC, EDSAC, UNIVAC, IBM 701Advantages:

Vacuum tubes were the only electronic component. These computers were the fastest calculating device of their time.

Disadvantages: They were too bulky in size. It was unreliable. They were produces large amount of heat. Frequently computer hardware was failure in this generation. It requires constant maintenance and Air condition. It was non-portable

2nd Generation (1955-1964) 2nd generation computer used transistors in place of vacuum tubes. Transistor is an

electronic switching device, was invented at Bell Laboratories in 1947 by John Bardeen, Willian Shockley and Water Brattain. It consumed almost one-tenth the power consumed by a tube

Ex: -1BM1400Advantages:

It was fastening then 1st generation. It was small in size and more reliable. It consumed much less power than 1st generation computers. It easier to program and use than the first-generation computers. They were produces less amount of heat.

Disadvantages:




It requires maintenance and air conditioning room.

3rd generation: (1964-1975) 3rd generation computer used Integrated Circuit chip(IC). So they are much more powerful

then 2nd generation. It was small in size and less power required. They used storage devices like magnetic tapes, discs. Integrated Circuit was invented by Jack St. Clair Kilby and Robert Noyce in 1985. This circuit consists of several electronic components like transistor, resisters and capacitors grown on a single chip of silicon. IC is known as Microelectronics because it contains large number of circuits in small surface of silicon. Initially the IC contained only about ten to twenty components. This technology was named as Small Scale Integration. Later IC chips became possible to integrate up to about hundred components on a single chip. This technology was named as Medium Scale Integration. Also high label language like FORTRAN & COBOL ware used in the 3rd generation. FORTRAN and COBOL were standardized by the American National Standards Institute (ANSI) in 1966 and 1968 respectively. FORTRAN stands for Formula Translation and COBOL stands for Common Business Oriented Language.

In this generation, John Kemeny and Thomas Kurtz of Dartmouth College introduced the concept of Timesharing Operation System. Timesharing Operating System allows a large number of users to directly access and shares the computing resources in a manner.

The development and introduction of minicomputers took place during 3 rd generation period. The first commercially available minicomputer, PDP-8 (programmed Data Processor) was introduced in 1965 by Digital Equipment Corporation (DEC). It could easily fit in the corner of a room and did not require the attention of a full time computer operator.

Ex:-IBM360Advantages:

They are much more powerful then 2nd generation. It was small in size and less power required. Even lower heat generated than 2nd generation computer. They were more reliable and less prone to hardware failures than 2nd generation

computer.Disadvantages:

It requires air conditioning room in many cases.4th generation (1965-1990):

4th generation machines are used silicon chips. This chip was possible to integrate over 30000 electronic components on a single chip. This technology was named as Large Scale Integration (LSI). After, this chip was possible to integrate about one million electronic components on a single chip. This technology was named as Very Large Scale Integration (VLSI). In this generation, development the electronic chip is known as microprocessor which used for creation of a microprocessor. A microprocessor contains all the circuits needed to perform arithmetic logic and control functions on a single chip.

Another significant development during the 4th generation period is known as networking. It was high speed computer networking, which enabled multiple computers to be connected together, to enable them to communicate and share data. Local Area Network became popular for connecting several dozen or hundred computers within organization. Wide area Network became popular for connecting computers located at larger distance. In this generation, Graphical User Interface (GUI) was developed. GUI was providing icons and menus, which users can select with a mouse. During 4th generation period, the UNIX operating system and ‘C’ programming language became very popular. Operating system was introduced to provide multiprogramming system.




Advantages: It doesn’t require air condition in must case. Hardware failure is negligible and hence minimal maintenance is required. Heat generated is negligible in these generations. They consumed much less power than the 3rd generation computer.

Disadvantages: It requires highly sophisticated technology.

5th generation (1989-2005):The 5th generation computer is states with Pentium and used microchip technology. The

VLSI technology became ULSI (Ultra Large Scale Integration) technology in the fifth generation. The ULSI having ten million electronic components. Input & output devices, Programming, internet, CD-ROM, floppy disk, hard disk and Multiprocessing facilities are developed in this generation.Advantages:

Searching for artificial intelligence.6th generation (2005 onwards): -

In 6thgeneration, the since have been developed much more things in our computer. Now a day we are using multiprogramming, multitasking, in super computers. Advantages:

Significant research.Classification of computer:

Classy a computer can be classified in to several ways according to the purpose that is follows.

1. Digital computer2. Analog computer3. Hybrid computer

Digital computer: The digital computer works with digits. In other word a digital computer is a counting device. All the expressions are coded into digits (0-9). Inside the computer it manipulates them instruct on. It has low memory power.Analog computer:

It is unlike a digital computer. It is used to measuring voltage, speed. Also it can use to count signal & display output continuously when current is flow within it. But the accuracy of this machine is quite low.Hybrid computer:

Hybrid computer is one, which combines best feature of analog or digital computer. These machines are used for scientific & industrial sectors.

Again the computers are divided into 4 categories as per this & purpose. 1. Microcomputer2. Mini computer3. Mainframe computer 4. Super computer

Microcomputer:These are the smallest in size and memory. So they are single user and used as personal

computer in small jobs and it is less efficient, by the introduced of micro chips it became so powerful.

Ex: -home PC.




Minicomputer:It is larger the microcomputer with multitasking facility. By involving centralized Processing

system or in other word user can transform the data during a specified area like business, education, and scientific and engineering fields.

Ex: -Air ticket railway reservation.Mainframe computer:

These computers are very big in size with a powerful process. High speed, large memory accepts in big job. They involved in multitasking by decentralized processing system or in other word we can transfer the data universally.

Ex: - Air ticket railway reservation.Super computer:

The powerful main frames are called as super computer. They are used in weather forecasting, nuclear research center, and in military application. It is multi tasking, multi user, multi-programmable computer with lots of memory power.

On use of computer are again classified into 2types they are, 1 general computer 2. Special computer

General purpose:A general purpose computer is designed to meets the needs of many different

applications. When one job is over, the instruction for another job can be loaded into the memory. These are broadly classified as micro -computer, minicomputer, main frame computer and super computer.Special purpose:

A special purpose computer is dedicated as per requirements of a particular set of application. The computerized programs loaded in the chips. They are used cameras, TV sets, watch, singing toys etcAbout the computer:

A total computer system includes both hardware & software. The computer hardware tells us the physical equipments necessary for a computer. Software is a set of instruction that directs the computer (CPU) to perform a particular task into a particular order. It related each other and can’t function independently. In other word when we studied that language of computers is known as software. Computer system has two main units that is Hardware and Software.1. Hardware:

The study of physical components of computer is known as hardware. The physical devices that make up the computer are called hardware. A computer’s hardware consists of interconnected electronic devices that we can use to control the computer’s operation, input and output. It is combination of mechanical electrical devices. So it has four types of devices.

1. Input device 2. Output device3. Processing device4. Storage device

Input device:The devices by which enter or input data or instruction into the computer for processing is

called input device. Input devices accept data and instructions from the user. There are many devices. Some important input devices are keyboard, mouse, joysticks, light pen, optical scanner, touch screen, microphone for voice as input and trackball.Keyboard:




Key board is most common input device. It allows data entry into a computer by a input device. The keyboard is connected to the back side of the CPU. There are alpha numerical keys such as A to Z, 0 to 9, special character (! , @, # $etc.) and mathematical symbol in the keyboard. There are ctrl, shift, alt which are used combined with some other function key. There are function key such as f1 to f12, four cursor movement keys and special keys such as page down, page up, home, end, insert and delete are used in case of running different types of program. The back space key is used to erase the left side text of the cursor position. The Del or delete key is used to erase the right side text of the cursor position. The caps lock key will be type in upper case letter. Mouse:

It is an input device. It is an electro-mechanical, hand-held device. It is a point and device. It is held in one hand and moved across a flat surface. The mouse pointer moves on the screen the direction of the mouse movement. The mouse point is also known as graphics corner. There are used in every function of the any time. There are three bottoms such as left and right bottom and round bottom. A mouse is used replace hard to remember key combinations with easier point and click actions. There are two types of mouse. They are optical mouse and mechanical mouse. An optical mouse has no moving part. It is used with a special pad covered with a grid of vertical and horizontal lines. A mechanical mouse detects the direction in which the ball is rolling and moves the screen pointer accordingly.Joystick:

It is also a pointing device which work on the same way us a track ball. We make movement of the mouse pointer there is a stick on the top of the stick and there is a small in the top. Joysticks are used in case of video game.Light pen:

There is pen like device used to draw directly on the monitor. This is called light pen. A light pen is similar to a mouse, except that with a light pen we can move the pointer and select objects on the display screen by directly pointing to the objects with the pen. Touch screen:

The VDU screens are designed such that the touch of a particular point of the screen with our fingers is recognized by the system. These are very useful when menu driven programs are run. The menu is displayed in the screen and the user just touch the item to be selected with fingers.

Scanner:Scanners are used to scan picture and scripts and store them in computer. If a picture has

to be stored in computer, the picture can be scanned by using scanner. While scanning the picture is held below the scanner. Immediately the scanner digitizes the picture and stores it in the computer. We could immediately see the picture in the computer screen. There are several types of scanner. The color scanners are capable of scanning color pictures with high resolution. The hand scanners are used in DTP centers to scan signatures and logos. Track ball:

It is the most important of input devices. It moves much similar to the mechanical mouse. In case of track ball is placed on the right side of the keyboard to move the mouse pointer rolled the ball with the finger. There are usually one to three buttons next to the ball which you see just like mouse button.Optical character reader (O.C.R):

It is an input device which can be use the printed character directly and understand them. For this purpose each character can be printed standard shape, which is standardized by ANSI




(American national standardized institute). This device is not hundred percent successful because it is very difficult to write a character in a particular cell.

The advantage of OCR is that no internet device is needed during the preparation of data. The disadvantage of this device that the equipments are very expensive and any small variation in the character shape, we need to incorrect result. Optical mark reader (O.M.R):

These input device are capable of accepting a predefine type of mark made by pencil or pen. It is mostly used in correcting multiple choice questions in competitive examinations.

Optical bar reader (O.B.R):The data codes in the form of small lines are known as bar code data. The bar code

represented as alpha numerical data by combination of vertical lines. This type of scanner is used in super market and department.Magnetic ink character reader (M.I.C.R):

It is similarly to O.C.R. It is used by banking industry for vary fast and large volume of checks. The bank which is used a specify type of ink which is called magnetic ink for writing checks number bank identification number and account number. Output device:

Output devices are used to show the information stored in a computer or the result of any processing done by the computer to the outside of world. The output unit of the computer presents the result of calculation. The V.D.U. screen or monitor, printers and plotters are some popular output devices. Some output units are card punch, paper tape, punch m magnetic tape and magnetic disk. Visual Display Unit (V.D.U):

It is most commonly use in output devices. Generally monitor is considered as visual display unit which is like a television screen. The result is displayed on the screen the VDU screen act as an effective man machine interface in the field of information technology. There are monochrome soft white screen and color screen. Now-a-days color screens are widely used almost all computers. A VDU normally consists of 20 rows and 80 columns, the screen is represented by an array of dots are called pixels. It has 200 pixels from top to button and 640 pixels left t0 right.

There are basically 6 types of technology used for constructing display screen. 1. Cathode Ray Tubes (CRT)2. Liquid Crystal Display (LCD)3. Light Emitting Diodes (LED)4. Plasma Display Panels (PDP)5. Vacuum Florescent Display (VFD)6. Electric Luminescent Display (ELD)

Printer:Printers are the most popular output devices. They produce printed output of results

programs and data. Printers are the mostly used output devices today for producing hard-copy output. There are different types of printers depending upon the printing mechanism, speed and quality of printing. Impact printer:

The printer that can be used to produce multiple copies of a document in a single printing by using carbon paper is known as impact printer.Dot-Matrix printers:




Dot-Matrix printers are character printers which print one character at a time. It is an output device. A dot matrix printer has a print head, which can move horizontally across the paper. It allows the printer to print many special characters, different sizes of print and the ability to print graphics such as charts and graphs. It is impact printer. Inkjet printer can be used to produce multiple copies by using carbon paper. It is slow and speed usually ranging between 30 and 600 characters per second. Drum printers:

Drum printers are line printers, which print one line at a time. It consists of a solid cylindrical drum with characters embossed on its surface in the form of circular bands. Each band consists of all the printing characters supported by the printer in its character set and the total number of bands is equal to the maximum number of characters that can be printed on a line. The drum rotates at a high speed.

A drum printer with 132 characters per line and supporting a character set of 96 characters. It is an output device. It is impact printers. The drum printers are print by hammering the paper and the inked ribbon against the characters embossed on the drum. The drum of drum printer is can’t be changed. Typical speeds of drum printers are in the range of 300 to 2000 lines per minutes. Chain printers:

It is a line printer, which print one line at a time. The chain printer consists of a metallic chain or band on which all the characters of the character set supported by the printer are embossed. Chain printers are impact printers because they print by hammering the paper and the inked ribbon against the characters embossed on the chain. They can be used to produce multiple copies by using carbon paper or equivalent. Typical speed of chain printers re in the range of 400 to 3000 lines per minutes. Non Impact printer:

The printer that can’t be used to produce multiple copies of a document in a single printing by using spraying ink on the paper is known as impact printer.Inkjet printers:

Inkjet printers are character printers, which form characters and all kinds of images by spraying small drops ink onto the paper. It is an output device. It is a non-impact printer. They are print by spraying ink on the paper. Inkjet printers cannot be used to produce multiple copies document in a single printing. Inkjet printers are slower than dot-matrix printers with speeds usually ranging from 40 to 300 characters per second. Laser printer:

Laser printers are page printers which print one page at a time. The main components of a laser printer are a laser beam source, a multi sided mirror, a photoconductive drum and toner. Laser printers produce very high quality output, because they form characters by vey tiny ink particles. Laser printers are non impact printers, because they do not have hammers striking on an inked ribbon or paper. Laser printers cannot be used to produce multiple copies of a document in a single printing.

Processing device:The procedure that transforms raw input data into useful information for output is called

processing. The device which are used for process to the user data or instruction for result is called processing device.

Ex- CPUCentral processing unit (CPU):




The procedure that transforms raw input data into useful information for output is called processing. To perform this transformation, the computer uses central processing unit. The CPU or processor is the “brain” of the computer. All major calculations and comparisons performed by a computer are carried out inside its CPU. The CPU is responsible for activating and controlling the operations of other units of the computer system. The CPU has three basic parts they are

1. Control unit (CU)2. Arithmetic logic unit (ALU)3. Register

Control unit:The control unit manages all the computer resources and coordinates all the computer

activities it contain the basic instruction for execution of programs. So any type of data can operate or perform in CPU in other word it is the brain of computer. A list of all the operations execute by user it performs on CPU. The control unit can thought and direct to the CPU by using all data.Arithmetic logic unit:

When control unit check the data an instruction that involves mathematically calculation decision means arithmetic operation (add, subtract, multiply, divide) or a logical operation (<,>,=) it passes the control to the second component the ALU. It does any types of mathematical operation. Microprocessor is a single tiny silicon chip.Register:

The register is smallest high storage area in the CPU. When we put some data through keyboard or mouse the data must have represented in this resister before it can process. It does not store the data. The length of register equals the number of bits it can store. Hence a register can store 8 bits normally. Now CPU has 32-bits or 64 bits registers. There are different types of registers such as:

Memory Address registers (MAR): it holds the address of the active memory location. It is located from the program control register when an instruction is read from memory. Memory Buffer Register (MBR): It holds the contents of the memory word read from or written in memory. A word to be stored in a memory location must first be transferred to the MBR, from where it is written in memory.Program Control Register (PCR): It holds the address of the next instruction to be executed. Accumulator register (AR): It holds the data to be operated upon the intermediate results and the results of processing. It is used during the execution of most instructions. Instruction Register (IR): It holds the current instruction, which is being executed. As soon as the instruction is stored in this register, the operation part and the address part of the instruction are separated. The address part of the instruction is sent to the MAR and the operation part is sent to control unit. Input/output Register: it is used to communicate with the input/output devices. All information such as instruction and data are transferred to this register by an input device.

Storage device:The devices which are used for store the data or information for feature reference is called

storage device. There are two type of storage device such as primary and secondary storage device.Storage Evaluation criteria

Any storage unit of a computer system is characterized and evaluated based on some properties such as:




Storage capacity: it is the amount of data which can be stored in the storage unit. A large capacity is desired. As compared to secondary storage units, primary storage units have less storage capacity. Access time: it is the time required to locate and retrieve stored in the storage unit, in response to a program instruction. As compared to secondary storage units, primary storage units have faster access time.Cost per bit of storage: it refers to the cost of a storage unit for a given storage capacity. As compared to secondary storage units, primary storage units have higher cost per bit of storage.Volatile: if the storage unit can retain the data stored in it, even when the power is turned off or interrupted, it is called non-volatile memory. If the data stored are lost, when the power is turned off or interrupted, it is called volatile memory. In all computer system, the primary storage units are volatile and secondary storage units are non-volatile. Random access: If the time taken to access a piece of data from the storage unit is independent of the location of the data in the storage unit, it is called random access storage or random access memory.

The execution of an instruction by the CPU, during program execution, normally involves fallowing steps:

1. The CU takes the address of the next program instruction to be executed from the program control register, and reads the instruction from the corresponding memory address, into the instruction register of the control unit.

2. The CU then sends the operation part and the address part of instruction, to the decoder and the memory address register, respectively.

3. The decoder interprets the instruction and accordingly the CU sends signals to the appropriate unit, which needs to be involved in carrying out the task specified in the instruction.

Ex: if it is an arithmetic or logical operation, the signal is sent to the ALU. In this case, the CU also ensures that the data corresponding to the address part of the instruction is loaded in a suitable register in the ALU, before the signals sent to the ALU. The ALU performs the necessary operation on the data and signals the CU as soon as it has finished.

4. As each instruction is executed, the address of the next instruction to be executed is automatically loaded into the program control register, and step 1to 4 repeated.

Primary memoryEvery computer has such a storage space which is known as primary memory or main

memory or simply memory. It is a temporary storage area which is built into the computer hardware. Physically, this memory consists of some chips either on the motherboard or on a small circuit board attached to the motherboard of a computer system. The primary memory is 100 times faster than from a high speed secondary storage like disk.

In a computer the memory has been divided in two types like RAM ROM is known as temporary memory of computer or volatile memory of computer. Again ROM is known as permanent memory of computer. All types of data must be given a file name before store in to it. RAM activate ROM. RAM does all the work. The primary memory consists two types of memory that is

1. Random Access Memory 2. Read Only Memory

RAMThe CPU have not sufficient storage space to execute the program so the control unit store

the data and instruction receive from input devices into primary memory called RAM. RAM can store data indefinitely. RAM holds information only while the computer is on. http://bibhutinew.blogspot.in of 22



When the computer is turn off or restart the information disappears unless it has been store into it. RAM is known as volatile memory or temporary of computer. Again the RAM has divided into 3 types

1. Dynamic RAM (DRAM)2. Static RAM (SRAM)3. Synchronous Dynamic RAM (SDRAM)

ROMSome data and instruction remain permanently stored into memory which can’t be

changed. This memory is called read only memory. ROM contains a set of instruction that check to see whether the rest of memory is functioning properly. It is CPUs permanent storage device. So it can’t be change or lost. Thus it is known as non-volatile memory. Again it is divided into three categories like

1. Programmable ROM (PROM)a. Manufacturer PROMb. User PROM

2. Erasable PROM (EPROM)a. Ultra Voilet EPROMb. Electrically EPROM

Programmable ROM:It is non volatile storage i.e. the stored information remains intact even if power is witched

off. It is possible to read the stored information. ROM is known as PROM, because a user can program it. PROM are programmed to record information using a special device, is known as PROM-programmer. Manufacturer PROM:

Manufacturer PROM chips are supplied by the manufacturers of electronic equipment. It is not possible for user to modify the programs or data stored inside the ROM chips.User PROM:

User PROM is one in which the user can load and store read only programs and data. It is possible for a user to customize a system by converting his own programs to micro programs and storing them in a user programmed micro chip.Erasable PROM:

It is possible to erase information stored in an EPROM chip and the chip can be reprogrammed to store new information. Ultra Voilet EPROM:

The stored information is erased by exposing the chip for some time to ultraviolet light that is known as Ultra Voilet EPROM.Electrically EPROM:

The stored information is erased by using high voltage electric pulse that is known as Ultra Voilet EPROM. It is also known as flash memory. Flash memory is used in many new I/O and Storage devices.Cache memory:

When using to main memory, the memory processor speed mismatch with which the CPU can process instructions because there is a 1 to 10 speed mismatch between the processor and main memory. Hence many situations the performance of processors gets limited due to the slow speed of main memory. Obviously, the overall performance of processors can be greatly improved by minimizing the memory-processors speed mismatch. Cache memory is used for minimizing the memory processor speed mismatch. It is an externally fast, small between CPU and main memory.




It acts as a high speed buffer between CPU and main memory and is used to temporarily store very active data and instructions during processing. It is faster than main memory.

Secondary storage devices:To store large amount of data for longer period we use the secondary storage device. It is

non-volatile memory. We can transfer data from one place to another place by using this secondary storage device. It is like floppy disk, hard disk, magnetic tape, pan device, CD, DVD etc. these components are external storage devices of computer.

There are two types of secondary storage device such as:1. Sequential access device

a. Magnetic tape2. Direct access device

a. Magnetic diski. Floppy disk

ii. Hard disk1. Zip disk2. Disk pack3. Winchester disk

b. Optical disk i. CD-ROM

ii. WORM diskFloppy disk:

It is a magnetic storage media using flat circular platter. Floppy disk are primarily used on PCs. Information on a floppy disk is recorded in the magnetized states of particles of iron oxides evenly placed upon concentric circles known as tracks, tracks are further divided into sectors. Physical size and storage capability of disks vary. Type size capacity Double density 5.25” 360KB High density 5.25” 1.2MB Double density 3.5” 720KB High density 3.5” 1.44MB Very high density 3.5” 2.88MBHard disk:

It is non-removable enclosed magnetic disk included in most PCs. A hard disk holds much more information than a floppy disk is used to store relatively large amount of data. The physical size and storage capabilities of a hard disk vary. For PCs the storage capacities vary from 1GB to about 8-10 GB.Zip disks:

In this type, a single hard disk platter is encased in a plastic cartridge. A commonly used to Zip disk is having a storage capacity of about 100 MB, depending on the formatting style used by a particular computer system.Disk pack: A disk pack consists of multiple hard disk platters mounted on a single central shaft.Winchester disks:

A Winchester disk also consists of multiple hard disk platters mounted on a single central shaft.Magnetic tape:

Magnetic tape is the most popular storage medium for large data which are sequential access media and process which means to get to a particular point on the tape. The magnetic tape mainly used for taking backup of hard disk. In contrast disks are random access media because a http://bibhutinew.blogspot.in of 22



disk drive can access ay point at random without passing through intervening points. So the magnetic tapes can’t be practically used for data that we need often.Optical disk: The need for ever greater storage capacities has driven hardware many- factures to use optical storage technology as the main alternative to magnetic storage.

The two most popular types of optical disks are CDROM and WROM disk.

CDROM:CDROM stands for compact disk read only memory. It is most popular optical storage

medium. CDROM uses the same technology that is used in music CDs. One can’t write data to a CDROM but can always read it. A single CD can hold up to 650 MB of data. Larger CDs can store up to 20GB. WROM:

WROM stands for write once, read many. This disk allows the users to create their own CD-ROM disk by using a CD-Recordable drive which can be attached to a computer as a regular peripheral device.

Structure of computer

Software: A computer cannot do anything on its own. Computers always need proper instructions to

tell them what to do, how to do when to do. A set of instruction written in a sequence which is on processing gives out the information as desire by the user is known as program. Software is a set of instructions that makes the computer perform tasks.

A large program which helps the user in doing the task in a complete way is known as software. Relationship between hardware and software:

Both hardware and software are necessary for a computer to do useful job. Both hardware and software are complementary to each other. The same hardware can be loaded with different software to make a computer system

perform different types of jobs, just as different songs can be played using the same cassette player.


ALU: Arithmetic Logic UnitCU: Control UnitROM: Read Only MemoryRAM: Random Access Memory

Monitor, printer, speaker

Key board, mouse, magnetic tap, floppy disk, CD, DVD, pen drive , scanner , joy stick , light pen

OUTPUT UNIT

INPUT UNIT

ROMRAM

CUALU

REGISTER

PRIMARY MEMORY

SECONDARY MEMORY



Hardware is normally a onetime expense whereas software is a continuing expense. Basically there are two kinds of software like 1. System software2. Application software

System software:The software, which requirement for booting process of computer i.e. system switch of or

switch on is known as system software. System software is a set of one or more programs, designed to control the operation and extend the processing capability of a computer system. Hence system software makes the operation of a computer system more efficiently. It helps the hardware components work together. It provides execution of application. The programs included in a system software package are called system software.

Ex-DOS, Windows 98/XP, UNIX, LINUX, VISTA

Types of system software: Depending on its used, the system software is two types such as:-

I. Operating systemII. Utility software

Operating System:An operating system is a set of program use to control the operation of computer system.

The operating system can’t perform any application or does not give us any type of result. We can only make a print out of those particulars. An operating system is system software which acts an interface the user and hardware. Duties of an operating system: Every operating system has got four important duties such as

Processor management Memory management Device management Input output management

Types of an operating system:Depending on number of uses that can work on the operating system, there are two type

of operating system such as: - Single user operating system Multi user operating systemDepending on weather the operating system supports networks, there are two types such

as: - Network operating system Non network operating system

Structure of operating systemLogically an operating system is divided into two parts such as kernel and shell.

Kernel: It is a collection of one or more files which interact with the hardware to carry out a

specific type of task. It is linear layer of an operating system. It received valid data or instruction from the shell. It is common interpreter. It closes with the hardware. It executes the command. Shell:

It is a collection of one or more files which interact with the user. It is outer layer of an operating system. It received command i.e. data or instruction from the user. Then it verifies that weather the command is valid or not. If the command is invalid, it displays on error message. If http://bibhutinew.blogspot.in of 22



the command is valid then request the kernel on behalf the user to execute the command. It is also known as execution. It closes with the hardware. It verifies to the command.Booting:

It is a process of loading of operating system from the external device to the main memory. Depending on wane booting is done the booting is two types such as: -

1. Cool or cold or soft booting2. Warm or hot or hard booting

Cool booting: When the computer is switch on then booting which occurs at this time is called as cool booting. Hot booting: When the computer is booted the pressing control, alt, delete or key combination or by pressing the restart button then that type of booting is called as hot booting.

Utility operating system:The system software which interfaces between the operating system and the hardware is

called as utility software.

Application software: The software, which not requirement for booting process of computer i.e. system switch

of or switch on is known as Application software. Application software is a set of one or more program, designed to solve a specific problem or do a specific task. Similarly, a program written by a user to solve a particular research problem is also known as application software. The programs included in an application software package are called application software.

Ex. - MS Word, MS Excel, Photoshop, Type tutor etc.

Programming Language: A communication between two parties always needs a common language to

communication each other. So the language is used to communicate between the computers the user is known as programming language. They are two types such as Low level language and High level language.

Low level language:In the first generation low level languages are used communicate with computer user.

Again the low level language was divided into two types1. Machine language2. Assembly language

Machine language: The binary code (0, 1) is the only method of communication with a computer. A user must

be convert normal language to binary language before feed into a computer is known as machine level language. It is used in 1st generation.Assembly language:

This is a low level language which user general statement to generate machine code. This language is also called as second generation language. The user must be adopting programming language after machine code. A program written in assembly language must be translated into machine language before the program is executed. The translation can be donning by a programmer known as assembler.

High level language:In third generation high level language were introduced. It is a programming language that

uses grammatical or mathematical or those language used by us. That is known as high level language. But every language must be a series of logical stapes or in a sequence. Again this high level language is divided into two categories




1. Interpreter language2. Compiler language

Interpreter An interpreter first reads each line to the program and converts them from unsolved

problem to solved problem. If it finds the line, error – free, it executes and thus the process continues till the end of program. Compiler:

A compiler is a program written in machine level language whose function is to translate the high level program into the machine level program. A compiler usually compiles the whole program from first to last line before attempting to solve the program.

Number systemIntroduction:

A computer system doesn’t understand our language. When data is typed into a computer, the keyboard converts each keystrokes into a binary character codes and vice versa.Binary:

A computer can store and process the data in two state devices. It can be either ON or OFF. So two symbols numerically used are 0 and 1. Definition:

Number are written in a systematically way or sequential way is called number system. Type of number system:

Depending on the position of the number, number systems are two types:1. Non-positional number system2. Positional number system

Non-positional number system:In early days, human beings counted on fingers. When ten fingers were not adequate,

stones, pebbles or sticks were used to indicate values, this method of counting is called non-positional number system. In this system, we have symbols, such as I for 1, II for 2, III for 3, etc. each symbol represents the same value, regardless of its position in the number and the symbols are simply added find out the value of a particular number.Positional number system:

In a positional number system, there are only a few symbols called digit and these symbols represent different values, depending on the position, they occupy in the number. The value of each digit in such a number is determined by three considerations:

The digit itself. The position of the digit in the number. The base of the number system.




Depending on base of the number, positional number systems are 4 types:I. Binary number systemII. Decimal number systemIII. Octal number systemIV. Hexadecimal number system

Binary number system:In this number system, the base is 2. Hence there are only two symbols and digits 0 or 1.

Latest single digit is 1. Example: (1101)2

In this number system we are fallow three rules: In addition

1+1=10, 1+0=1, 0+1=1, 0+0=0 In subtraction

1-1=0, 1-0=1, 0-1=-1, 0-0=0 In multiplication

1x1=1, 1x0=0, 0x1=0, 0x0=0Some example:

Q1. (11011)2 + (111)2 = (?)2 11011

+ 111 100010

Q2. (110001)2 - (101)2 = (?)2

110001- 101101100

Q3. (111)2 x (11)2= (?)2

111 x 11 111 111 10101

Decimal number system:The number system used almost universally by human is called decimal number system. In

this number system, the base is 10. Hence there are only ten digits or symbols: 0, 1… 9. The latest single digit is 9.

Example: (986)10

Octal number system:In this number system, the base is 8.hence there are only 8 digits or symbols: 0 to 7. The

latest single digit is 7.Example: (123)8

Hexadecimal number system:In this number system, the base is 16. hence there are only 16 digits or symbols:0 to

9,A,B,C,D,E,F Where A=10, B=11, C=12, D=13, E=14, F=15.Example: (BCA) 16, (3EF) 16, (123)16.




Converting to decimal from another base: Multiply to every digit of the given number by determine the column value of each digit. Sum of products calculated in step-1. The total is the equivalent value in decimal.

Some basic example:Q1. (234)8 = (?)10

234 = 2 X 82 +3 x 81 + 4 x 80

= 2 x 64 +3x 8 +4x1 = 128+24+4 = 156

Q2. (111001)2 = (?) 10

111001 = 1x25+1x24+1x23+0x22+0x21+1x20

= 32+16+8+0+0+1 = 57

Q3. (BCA) 16= (?)10

BCA= Bx162+Cx161+Ax160

=11x256+12x16+10x1 =2816+192+10

= 3018 Converting from decimal to another base:

Divided the number by the base of required value. Write the reminder as rightmost digit of the new quotient number. We are continuing this process until quotient is equal to zero. Write reminder value down to up this number is equivalent value of required Value.

Q1. (546)10= ( ) 2

2 5462 273 02 136 12 68 02 34 02 17 02 8 12 4 02 2 02 1 0 0 1(546)10= (1000100010) 2

Q2. (270)10= ( ) 16

16 270 16 16 14 E 16 1 0 0 1

(270)10= (10E) 16

Q3. (98)10= ( ) 8




8 988 12 28 1 4 0 1(98)10= (142) 8

Converting from base other than 1o to base other than 10 : Convert the original number to a decimal number system. Convert the decimal number to a required number system.

Q1. (234)8 = (?)2

234 = 2 X 82 +3 x 81 + 4 x 80 = 2 x 64 +3x 8 +4x1 = 128+24+8 = 156 (234)8 = (156)10

2 156 2 78 0 2 39 0 2 19 1

2 9 1 2 4 1 2 2 0

1 0(156)10= (10011100)2

(234)8 = (10011100)2



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