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FUNDAMENTALS OF COMPUTER TECHNOLOGY

COMPUTER

A computer is an electronic device which accepts input data, processes and gives the

output accurately. The computer can perform arithmetic operations like addition,

Subtraction, multiplication and division and also perform logical Operations by comparing

data. This logical ability of computer helps Us to select verity of choices. But a computer

user must always remember that even though it can do any complicated calculations it is still

a machine, it has no brain and hence it cannot think.

A computer is a general purpose device that can be programmed to carry out a

finite set of arithmetic or logical operations. Since a sequence of operations can be readily

changed, the computer can solve more than one kind of problem.

Conventionally, a computer consists of at least one processing element, typically a central

processing unit (CPU) and some form of memory. The processing element carries out

arithmetic and logic operations, and a sequencing and control unit that can change the

order of operations based on stored information. Peripheral devices allow information to be

retrieved from an external source, and the result of operations saved and retrieved.

The first electronic digital computers were developed between 1940 and 1945 in the

United Kingdom and United States. Originally they were the size of a large room,

consuming as much power as several hundred modern personal computers (PCs).[1] In

this era mechanical analog computers were used for military applications.

Modern computers based on integrated circuits are millions to billions of times more

capable than the early machines, and occupy a fraction of the space.[2] Simple computers

are small enough to fit into mobile devices, and mobile computers can be powered by

small batteries. Personal computers in their various forms are icons of the Information Age

and are what most people think of as "computers". However, the embedded computers

found in many devices from mp3 players to fighter aircraft and from toys to industrial

robots are the most numerous.

In its most basic form a computer is any device which aids humans in performing

various kinds of computations or calculations. In that respect the earliest computer was the

abacus, used to perform basic arithmetic operations.

Every computer supports some form of input, processing, and output. This is less

obvious on a primitive device such as the abacus where input, output and processing are

simply the act of moving the pebbles into new positions, seeing the changed positions, and

counting. Regardless, this is what computing is all about, in a nutshell. We input

information, the computer processes it according to its basic logic or the program currently

running, and outputs the results.

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Modern computers do this electronically, which enables them to perform a vastly

greater number of calculations or computations in less time. Despite the fact that we

currently use computers to process images, sound, text and other non-numerical forms of

data, all of it depends on nothing more than basic numerical calculations. Graphics, sound

etc. are merely abstractions of the numbers being crunched within the machine; in digital

computers these are the ones and zeros, representing electrical on and off states, and

endless combinations of those. In other words every image, every sound, and every word

have a corresponding binary code.

While abacus may have technically been the first computer most people today associate the word

“computer” with electronic computers which were invented in the last century, and have evolved

into modern computers we know of today

History - Generation of computers:- The electronics computer came into

existence during the middle of this century. Generation of computer is classified into

The following stages.

1) Ist generation Computer(1945-50): During this period, business computers invented. The

main Parts of these computers are, ”vacuum tubes” or “valves”.

First electronic computers used vacuum tubes, and they were huge and complex.

The first general purpose electronic computer was the ENIAC (Electronic Numerical

Integrator And Computer). It was digital, although it didn’t operate with binary code, and

was reprogrammable to solve a complete range of computing problems. It was

programmed using plug boards and switches, supporting input from an IBM card reader,

and output to an IBM card punch. It took up 167 square meters, weighed 27 tons, and

consuming 150 kilowatts of power. It used thousands of vacuum tubes, crystal diodes,

relays, resistors, and capacitors.

The first non-general purpose computer was ABC (Atanasoff–Berry Computer), and other

similar computers of this era included german Z3, ten British Colossus computers, LEO,

Harvard Mark I, and UNIVAC. They were Costly and difficult to maintain. These computers

generate heavy heat and require heavy air-cooling /conditioning.

2) IId generation Computers(1951-60): In this generation vacuum tubes are replaced by

“Transistors”. The second generation of computers came about thanks to the invention of

the transistor, which then started replacing vacuum tubes in computer design. Transistor

computers consumed far less power, produced far less heat, and were much smaller

compared to the first generation, albeit still big by today’s standards.

The first transistor computer was created at the University of Manchester in 1953. The

most popular of transistor computers was IBM 1401. IBM also created the first disk drive in

1956, the IBM 350 RAMAC.

The size of the computer is reduced and still generates heat. These also require air-cooling.

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3) IIIrd generation of computers(1961-70) :These computers are started by using

“Integrated circuits” – (IC). The invention of the integrated circuits (ICs), also known as

microchips, paved the way for computers as we know them today. Making circuits out of

single pieces of silicon, which is a semiconductor, allowed them to be much smaller and

more practical to produce. This also started the ongoing process of integrating an ever

larger number of transistors onto a single microchip. During the sixties microchips started

making their way into computers, but the process was gradual, and second generation of

computers still held on.

First appeared minicomputers, first of which were still based on non-microchip transistors,

and later versions of which were hybrids, being based on both transistors and microchips,

such as IBM’s System/360. They were much smaller, and cheaper than first and second

generation of computers, also known as mainframes. Minicomputers can be seen as a

bridge between mainframes and microcomputers, which came later as the proliferation of

microchips in computers grew. The size of the computer becomes less and heat was almost

reduced. Minimum air-cooling is required. Operating system Concepts are introduced in this

generation.

4) IV th generation of computers(1971onwards): VLSI (Very large scale integration)

“Microprocessors” or ”Chips” are the main parts of this generation computers.

First microchips-based central processing units consisted of multiple microchips for

different CPU components. The drive for ever greater integration and miniaturization led

towards single-chip CPUs, where all of the necessary CPU components were put onto a

single microchip, called a microprocessor. The first single-chip CPU, or a microprocessor,

was Intel 4004. The advent of the microprocessor spawned the evolution of the

microcomputers, the kind that would eventually become personal computers that we are

familiar with today. Size of the computer is very small and producing of heat is negligible.

This doesn‟t require any air-cooling.

5) V th generation of computers : These are now in experimental stage and trying to build

Artificial intelligence (AI) and Super Conductivity.

GENERATION PERIOD Parts Speed Air-cooling

I 1945-50 Vacuum tubes Very slow Required

II 1951-60 Transistors Slow Required

III 1961-70 Integrated Circuits Fast Minimum Required

IV 1970 onwards Micro processors Or chips Very fast Generally Not required

V Artificial intelligence & Super

conductivity.

Super fast Not required

CLASSIFICATION OF COMPUTERS

Computers are classified based on two categories:-

A) Based on principle of operations.

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B) Based on memory size.

A) Classifications based on their principle of operations:-

1) Digital computers:- These represent in the form of data into digits and then all the

operations are done on these digits at extremely fast rates A computer that stores data in terms of digits (numbers) and proceeds in discrete steps from one

state to the next. The states of a digital computer typically involve binary digits which may take

the form of the presence or absence of magnetic markers in a storage medium ( memory), on-off

switches or relays. In digital computers, even letters, words and whole texts are represented

digitally. Unlike analog computers, digital computers can only approximate a continuum by

assigning large numbers of digits to a state description and by proceeding in arbitrarily small

steps. 2)Analog computers:- These computers set an analogy of the problem and operate by

measuring rather than Counting.

An analog computer is a form of computer that uses the continuously changeable

aspects of physical phenomena such as electrical, mechanical, or hydraulic quantities to

model the problem being solved. In contrast, digital computers represent varying quantities

symbolically, as their numerical values change.

3)Hybrid computers:- These computers make use of both Analog and digital computer

principles and techniques.

There is an intermediate device, a 'hybrid' computer, in which an analog output is

converted into digits. The information then can be sent into a standard digital computer for

further computation. Because of their ease of use and because of technological

breakthroughs in digital computers in the early 70s, the analog-digital hybrids were

replacing the analog-only systems.

Hybrid computers are used to obtain a very accurate but not very mathematically precise

'seed' value, using an analog computer front-end, which value is then fed into a digital

computer, using an iterative process to achieve the final desired degree of precision. With

a three or four digit precision, highly accurate numerical seed, the total computation time

necessary to reach the desired precision is dramatically reduced, since many fewer digital

iterations are required (and the analog computer front end reaches its result almost

instantaneously).

4)Optical Computers:- These are super high speed computers yet to be developed which

shall work on quadree system basic.

B) Classifications based on Memory size:- Computers are also classified based on their

memory sizes.

1)Micro Computers:- These computers uses Micro processes and are very small in size.

The memory is up to 12MB. Following are the different types of micro computers.

a) Home computers b)Personal Computers c) Laptop Computers

Home computers are generally used by Hobbyists laptop computers are very Small and light in

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size and can be carried from place to place as a briefcase. Personal computers are used by

professionalists for professional application, Business application etc.,

2) Mini Computers:-

These are the very fast computers and five times faster than A micro computer and CPU

speed is about 5000 Kilo instructions per second

3)Main frame computers:- These are the large size computers which occupies a large air

Condition space and have

main memory size up to 128mb. Since all its Peripherals are mounted in large cabinet type

of frames. These computers are used in large industrial set-ups.

4) Super computers:- These are very fast computers having memory size of about 250mb

A supercomputer is a computer at the frontline of current processing capacity, particularly

speed of calculation. Supercomputers were introduced in the 1960s and were designed

primarily by Seymour Cray at Control Data Corporation (CDC), and later at Cray

Research. While the supercomputers of the 1970s used only a few processors, in the

1990s, machines with thousands of processors began to appear and by the end of the

20th century, massively parallel supercomputers with tens of thousands of "off-the-shelf"

processors were the norm.[2][3]

Characteristics / Special features of computers:-

a) Speed:- computers are very fast calculators.

b) Accuracy:- Results of computer is hundred percent accurate i.e. according to data

supplied to it. “GIGO” is one of the name given to the computer, this means

“Garbage In Garbage Out” .i.e. the computer does not think as human brain and

doesn‟t take any decision on the data as human brain decides.

c) Memory:- There is no limit to the storage of information by modern computers.

Any type of information can be Stored in the memory.

d) Versatality : Computers are versatile machines and can be used for any tasks

Other features are,

1) It never gets bored. And does variety of jobs.

2) Performs the tasks as per the instructions.

COMPUTER APPLICATIONS: Following are the different areas and uses of computers

1)Scientific applications. 2)Metrology and weather forecasting. 3)In business and office.

4)In transportations(on line reservation) 5)In banks and financial institutions.

6)In electronics fund transfer. 7)In Industries and Engineering.

8)Education (School and colleges) 9)Arts and modelling. 10)Voice mail.

11)Facsimile transmission(FAX) 12)In music. 13)In electronic mail. and INTER NET

ORGANIZATION OF COMPUTERS:- The following shows the organization of a computer,

the following are the three important parts of a computer.

1) Input devices.:- The device used to enter data into the computer is called as Input device.

E.g.:- Key boards, Mouse, Joy stick etc.,

2) Out put device:- Devices which displays the input data and result of input after

processing are called as output devices. E.g.:- Monitor, Printer, Speaker etc.,

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3) Central processing unit:-(CPU) This is the main part of a computer called as the heart

or the brain of the computer. Control unit, Memory unit and Arithmetic and logic unit

(ALU) are the main parts of this CPU. To store the data/program permanently a

secondary storage unit like Hard disk , is attached to this CPU BLOCK DIAGRAM OF A COMPUTER

Generally a computer is having following parts(blocks)

a) Input devices : These are the devices used to feed data and information into CPU

Eg. Key board, Mouse, joy stick etc,

b) Output Devices : These are the devices used to view the input data and output

information of processing. Eg. Monitor, Printer etc.

c) Secondary storage devices : These are used to store data and programs eg. Hard

disk, Floppy etc

d) Central Processing Unit (CPU) - The part of the computer that executes the

instructions (program) stored in memory. The CPU is made up of the

a) Control Unit and the b) Arithmetic/Logical Unit. c) Memory Unit

III) CENTRAL PROCESSING UNIT:- (CPU) This is also called as heart or the brain of

the computer. It consists of following important parts.

A) Memory Unit. B) Control Unit. C) ALU(Arithmetic and logic Unit)

a) MEMORY UNIT:- It is the temporary area where the input is stored before

Processing and results are stored before sending to output and Intermediate results of

processing. Internal data storage in a computer. The memory is comprised of a large number

of individual cells, each with a unique number, known as its address, associated with it.

b) CONTROL UNIT:- Control unit of CPU controls the operations of programmers and

Commands in selecting, interpreting and in execution. It maintains The order and directs

the operations of the system. Although control Unit does not process data it acts as the

central nervous system for The other data manipulating components of the computers.

c) ALU (ARTHMATIC AND LOGIC UNIT):-This is the area where processing of programme

problems and commands is going to takes place. This is he component of the CPU that

IN PUT

DEVICE

CONTROL UNIT

MEMORY UNIT

ARITHMATIC &

LOGIC UNIT

OUT PUT

DEVICE

SECONDARY

STORAGE DEVICE

CENTRAL PROCESSING UNIT

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performs arithmetic and logical operations. Once the data are feed into the memory Unit

they will be transferred to ALU and the results are send back from ALU to memory unit.

PERPHERAL DEVICES

I) INPUT DEVICES:- Input devices are classified into 2 types .

1) Direct input devices: Devices which are directly feeds the information into CPU are called

as Direct Input Devices Ex:- Key Board, Mouse, Track balls, Joy stick etc.,

2) Indirect input devices:- These devices puts the information into the CPU, by using

other physical characters like light, magnetic field etc.,

E.g.:- a) MICR :- Magnetic Ink Character Reader. b) OCR :- Optical

Character Reader. c) BCR :- Bar Code Reader. Key board:

In computing, a keyboard is an input device partially modelled after the typewriter

keyboard which uses an arrangement of buttons, or keys which act as electronic switches.

A keyboard typically has characters engraved or printed on the keys, and each press of a

key typically corresponds to a single written symbol. However, to produce some symbols

requires pressing and holding several keys simultaneously or in sequence. While most

keyboard keys produce letters, numbers or signs (characters), other keys or simultaneous

key presses can produce actions or computer commands.

Mouse : In computing, a mouse (plural mice, mouse devices, or mouses) is a pointing device that functions by detecting two-dimensional motion relative to its supporting surface. Physically, a mouse consists of a small jude, held under one of the user's hands, with one or more buttons. It sometimes features other elements, such as "wheels", which allow the user to perform various system-dependent operations, or extra buttons or features can add more control or dimensional input. The mouse's motion typically translates into the motion of a pointer on a display, which allows for fine control of a Graphical User Interface.

SCANNER

In computing, a scanner is a device that optically scans

images, printed text, handwriting, or an object, and converts it

to a digital image. Common examples found in offices are

variations of the desktop (or flatbed) scanner where the

document is placed on a glass window for scanning. Hand-held

scanners, where the device is moved by hand, have evolved

from text scanning "wands" to 3D scanners used for industrial

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design, reverse engineering, test and measurement, orthotics, gaming and other applications.

Mechanically driven scanners that move the document are typically used for large-format

documents, where a flatbed design would be impractical.

JOYSTICK

A joystick is an input device consisting of a stick that pivots on a base and

reports its angle or direction to the device it is controlling. Joysticks are

often used to control video games, and usually have one or more push-

buttons whose state can also be read by the computer. A popular variation

of the joystick used on modern video game consoles is the analog stick.

The joystick has been the principal flight control in the cockpit of many

aircraft, particularly military fast jets, where centre stick or side-stick

location may be employed Joysticks are also used for controlling machines

such as cranes, trucks, underwater unmanned vehicles and zero turning

radius lawn mowers. Miniature finger-operated joysticks have been

adopted as input devices for smaller electronic

equipment such as mobile phones.

MICR

Magnetic Ink Character Recognition, or MICR (pronounced my-ker or micker), a

character recognition technology adopted mainly by the banking industry to facilitate the

processing of checks. MICR characters are printed with a magnetic ink or toner, usually

containing iron oxide. Magnetic printing is used so that the characters can be reliably read

into a system, even when they have been overprinted with other marks such as

cancellation stamps. The characters are first magnetized in the plane of the paper with a

North pole on the right of each MICR character. Almost all Indian, US, Canadian and UK

checks now include MICR characters at the bottom of the paper

OCR - Optical character recognition – OMR 'Optical

mark recognition'

OCR is a field of research in pattern recognition, artificial

intelligence and machine vision. Optical character

recognition (using optical techniques such as mirrors and

lenses) and digital character recognition (using scanners

and computer algorithms) were originally considered

separate fields. Because very few applications survive that

use true optical techniques, the OCR term has now been

Joystick elements: 1. Stick 2. Base 3.

trigger 4. Extra buttons 5. Autofire

switch 6. Throttle 7. Hat Switch (POV

Hat) 8. Suction Cup

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broadened to include digital image processing as well.

'Optical mark recognition' is the process of capturing data by contrasting reflectivity at

predetermined positions on a page. By shining a beam of light onto the paper the scanner is able

to detect a marked area because it reflects less light than the blank areas of the paper. Some

OMR devices use forms which are preprinted onto 'Transoptic' paper and measure the amount of

light which passes through the paper, thus a mark on either side of the paper will reduce the

amount of light passing through the paper.

BAR CODE (also barcode) is an optical machine-readable representation of data. Originally, bar codes represented data in the widths (lines) and the spacings of parallel lines and may be referred to as linear or 1D (1 dimensional) barcodes or symbologies. But they also come in patterns of squares, dots, hexagons and other geometric patterns within images termed 2D (2 dimensional) matrix codes or symbologies. In spite of there being no bars, 2D systems are generally referred to as barcodes as well.

A barcode reader (or barcode scanner) is an electronic device for reading printed barcodes. Like a flatbed scanner, it consists of a light source, a lens and a photo conductor translating optical impulses into electrical ones. Additionally, nearly all barcode readers contain decoder circuitry analyzing the barcode's image data provided by the photo conductor and sending the barcode's content to the scanner's output port.

II) OUTPUT DEVICES:-

1) Monitor:(VDU)

The most commonly used output device is a screen, also Called as the monitor. This is also

called as Visual Display Unit (VDU).

There are two types in monitors : a ) CRT Monitors b) LCD TFT monitors

a ) CRT Monitors

CRT stands for Cathode Ray Tube describing the technology inside a traditional computer

monitor or television set. It displays all the commands, we type on key board and also The

outputs. Characters on screen are generated by a matrix Of 5X7 dots, and are displayed

white on a black back ground. Typically screen displays 25 lines and 80 characters per line.

Generally available monitor size is 14” to 22”.

Some screens can also works in graphic mode in which They can display diagram. In

graphic mode screen is treated as an array of tiny dots called as the pixels (picture

elements). The colour screen or Monitor can typically display 16 different Colours. The CRT

monitor creates a picture out of many rows or lines of tiny colored dots. These are

technically not the same thing as pixels, but the terms are often used interchangeably. The

more lines of dots per inch, the higher and clearer the resolution. Therefore 1024 x 768

resolution will be sharper than 800 x 600 resolution because the former uses more lines

creating a denser, more detailed picture. Higher resolutions are important for displaying the

subtle detail of graphics. For text, resolution isn't as critical.

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b) LCD TFT monitors : A thin film transistor liquid crystal display (TFT-

LCD) is a variant of liquid crystal display (LCD) which uses thin film transistor

(TFT) technology to improve image quality (e.g. addressability, contrast). TFT

LCD is one type of active matrix LCD, though all LCD-screens are based on

TFT active matrix addressing. TFT LCDs are used in television sets,

computer monitors, mobile phones and computers, personal digital assistants,

navigation systems, projectors, etc.

2) PRINTER:- Printers are classified into two types

a) Impact printer:- This type of printers are prints the information by the

Principle of impact mechanism. E.g.:- Dot. Matrix Printer, Daisy Wheel printer,

chain printer

A Dot Matrix Printer or impact matrix printer is a type of computer printer with a print head that

runs back and forth on the page and prints by impact, striking an ink-soaked cloth ribbon against

the paper, much like a typewriter. Unlike a typewriter or daisy wheel printer, letters are drawn out

of a dot matrix, and thus, varied fonts and arbitrary graphics can be produced. Because the

printing involves mechanical pressure, these printers can create carbon copies and carbonless

copies.

b) Non-impact printer:- These are based on the principle of LaserJet, Inkjet and

Thermal methods. E.g.:- laser printer, Inkjet printers etc., A laser printer is a common type of computer printer that rapidly produces high quality text and graphics on plain paper. As with digital photocopiers and MFPs, laser printers employ a xerographic printing process but differ from analog photocopiers in that the image is produced by the direct scanning of a laser beam across the printer's photoreceptor.

Inkjet printers operate by propelling variably-sized droplets of liquid or molten material (ink) onto

almost any sized page. They are the most common type of computer printer for the general

consumer due to their low cost, high quality of output, capability of printing in vivid color, and ease

of use.

Like most modern technologies, the present-day inkjet has built on the progress made by many

earlier versions. Among many contributors, Epson, Hewlett-Packard and Canon can claim a

substantial share of the credit for the development of the modern inkjet. In the worldwide consumer

market, four manufacturers account for the majority of inkjet printer sales: Canon, Hewlett-

Packard, Epson, and Lexmark.

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PLOTTER : A plotter is a vector graphics printing device to print

graphical plots, that connects to a computer. There are two types of

main plotters. Those are pen plotters and electrostatic plotters.A

graphics printer that draws images with ink pens. It actually

draws point-to-point lines directly from vector graphics files. The

plotter was the first computer output device that could print

graphics as well as accommodate full-size engineering and

architectural drawings. Using different colored pens, it was also able to print in color long

before inkjet printers became an alternative.

COMPUTER MEMORY

MEMORY SIZE AND BINARY NUMBERS:-

Computer handles all the numeric and nonnumeric data only in terms Of binary

numbers “0”and/or “1”. Combined in various ways.

BIT:- BIT stands for Binary Digit and represents on-current or off-current in the circuit

of the computer and are represented by binary digits “0” and”1”. Here “1” represents on

current and “0”represent off current. Bit is the unit for representation of capacity of

memory units and is the smallest one.

BYTE:- To represent a character 8 bits are required, such a group of 8 bits are called as

a “BYTE”. Ie., 8 bits= 1byte.

Following are the different measurement units of the memory:-

8 BIT = 1 BYTE

(2)10 BYTE = 1024 BYTE = 1KB ( 1 Kilo Byte )

(2) 10 KB = 1024 K.BYTE = 1MB ( 1 Mega Byte)

(2) 10 MB = 1024 M. BYTE = 1GB ( 1 Giga Byte )

(2) 10 GB = 1024 G. BYTE = 1TB ( 1 Terra Byte )

(2) 10 TB = 1024 T. BYTE = 1PB ( 1 Peta Byte )

COMPUTER MEMORY:- Computer memory is classified into 2 groups,

a) Internal Memory(primary) & b) External Memory(Secondary Memory)

A) Internal Memory(primary) : These are the built in memories by the manufacturer Of the

CPU. These memory stores data temporarily. Internal Memory is classified into following

types. 1) Random Access Memory(RAM) 2) Read Only Memory(ROM) 3) Cache memory

1) Random Access Memory(RAM) : This is a temporary memory ( Volatile Memory ) Random-access memory (RAM) is a form of computer data storage. A random-access device

allows stored data to be accessed in very nearly the same amount of time for any storage location,

so data can be accessed quickly in any random order. In contrast, other data storage media such as

hard disks, CDs, DVDs and magnetic tape, as well as early primary memory types such as drum

memory, read and write data only in a predetermined order, consecutively, because of mechanical

design limitations. Therefore the time to access a given data location varies significantly depending

on its physical location.

2) Read Only Memory:- This type of memory units is having permanently stored

Programmes which are built at the time of manufacturing. These programmes cannot be

erased or changed. Data Of this memory will never get erased even if power is Switched off.

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Read-only memory (ROM) is a class of storage medium used in computers and other

electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with

difficulty, so it is mainly used to distribute firmware (software that is very closely tied to specific

hardware, and unlikely to need frequent updates). E.g.:- Boot program.

ROM is again classified as, PROM: EPROM: EEPROM:

Programmable read-only memory (PROM), or one-time programmable ROM (OTP),

can be written to or programmed via a special device called a PROM programmer.

Typically, this device uses high voltages to permanently destroy or create internal links

(fuses or antifuses) within the chip. Consequently, a PROM can only be programmed once.

Erasable programmable read-only memory (EPROM) can be erased by exposure to

strong ultraviolet light (typically for 10 minutes or longer), then rewritten with a process that

again needs higher than usual voltage applied. Repeated exposure to UV light will

eventually wear out an EPROM, After programming, the window is typically covered with a

label to prevent accidental erasure. Some EPROM chips are factory-erased before they are

packaged, and include no window; these are effectively PROM.

Electrically erasable programmable read-only memory (EEPROM) is based on a similar

semiconductor structure to EPROM, but allows its entire contents (or selected banks) to be

electrically erased, then rewritten electrically, so that they need not be removed from the

computer (or camera, MP3 player, etc.). Writing or flashing an EEPROM is much slower

(milliseconds per bit) than reading from a ROM or writing to a RAM (nanoseconds in both

cases).

3) Cache memory : A CPU Cache memory is a cache used by the central processing unit of a

computer to reduce the average time to access memory. The cache is a smaller, faster memory

which stores copies of the data from the most frequently used main memory locations. As long as

most memory accesses are cached memory locations, the average latency of memory accesses will

be closer to the cache latency than to the latency of main memory.

B) External Memory(Secondary Memory):- These are the memories where we store data

or programmers Permanently and is used whenever required. E.g.:- Hard disc, Magnetic

Tape, Floppies(Diskettes)etc.,

COMPUTER MEMORY

Internal (Primary)Memory External(Secondary) Memory (SSD)

E.g.:- Boot Programmes

Hard Disc, Floppy disc, Flash drive

ROM(Permanent) RAM (Temporary) Cache Memory

PROM EPROM EEPROM

HARDWARES AND SOFTWARES:-

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HARDWARES:- The physical, electrical and electronic parts which makes A computer

system are called as hardware these includes The parts such as pointer, printer, floppies

etc., we can feel and touch these things. E.g.:- CPU Chips, Monitor, Keyboards, Printer,

Mouse etc.,

SOFTWARES: These are the written programs, instructions stored in the memory parts of

the computer. It is not possible to get any physical feelings with these. e.g. : Operating

system – DOS, Windows and application soft wares - Ms word , Lotus, Tally, ect.,

Soft wares are classified into 2 main groups

1) System soft wares:( Operating Systems) : These soft wares refers set of programmes or

instructions needed to manage and co-ordinate the various parts and functions of a

Computer system. These are also called as operating system. Following are the different

system soft wares for computer,

a) MSDOS:- Micro soft Disc Operating System.

b) MS WINDOWS:- Windows 3.0, Windows 3.11, Windows 95/98, Windows NT

c) Unix, XENIX ,Os/2 etc.,

2) Application Soft wares:- These are the soft wares used in human needs and classified as

General software, customized software, utility soft wares. These soft wares Are used for

day to day application like maintaining of payroll, inventory Control, maintaining of accounts,

desk top publishing(DTP) etc.,

Following are the example for application soft wares.

a) Lotus-1,2,3 - used for making of spread sheet (statement)

b) d Base(IV,III+,III) /Fox pro - used to Database management.

c) WordStar - For processing of words(text

e) Ms Office - word(processing of words), Excel(spread sheet)

PowerPoint(Presentation type) Access( Data)

f) Page Maker/ Corel Draw - DTP Software

h) Auto cad - Designs and drawing of engineering.

i) Tally - Accounting package

Secondary Storage Devices(SSD):- These are the hardware parts of the computer and is

used to Store permanently, the different programmes and used when required Hard disc and

floppy disc (diskettes) are generally available SSD for a Computer.

HARD DISC:- Hard disc is made out of thin circular metal plates and coated with a

Magnetic material on both sides. A disk pack consists of a number of discs Mounted on a

central shaft, which rotates at a minimum speed of 3600 to 7200 revolution Per minutes. On

each of this disc information is stored in both surfaces. Each Surface is divided into a

number of invisible circles, called as tracks and each Track is further divided into sectors.

The capacity of a hard disc is measured In MB(megabyte) and GB(gigabyte). Generally

available hard disc capacity are 40 Gb to TB

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SSD

HARD DISK MAGNETIC TAPE

(40 MB TO 4.3 GB) FLOPPY

51/4” FLOOPY 31/2” FLOPPY

LOW DENSITY HIGH DENSITY LOW DENSITY HIGH

DENSITY

(360kb) (1.2mb) (720kb) (1.44mb)

FLOPPY DISC:-

(DISKETTES) Floppy discs are used to store programmes or files and they can be carried

Easily. The cost of these floppies is very cheep. These are made out of circular Plastic

sheet and coated with Iron Oxide. This disc is enclosed in a plastic Jacket to protect the

disc. There are different sizes available in floppy disc. Flowing are the two important sizes

available in the market.

1) 51/4” floppy:- This is also called as mini floppy disc. Size of this disc is

51/4”. There are two types in this disc by its capacity.

360KB:- This is called as low density disc and the capacity is 360KB. It is having 40

tracks /9 sectors.

1.2MB:- This is called as high density disk and the capacity is 1.2MB. It is having

80tracks /15 sectors.

2) 31/2” floppy:- These are called as MICRO FLOPPIES and the size of the disc is 3 ½ ”.

There are two capacities in these floppies. A) 720KB:- Low density disk. B) 1.44MB:- High

density disk having 80 tracks and 8 sectors per side.

3 ½”

MICRO FLOPPY MINI FLOPPY

5.25 “

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Miscellaneous topics:-

ENIAC:- ENIAC means Electronic Numerical Integrator And Computer.

This was the first valve based electronic computer of the world, which Is now invariably taken as

first computer of first generation of electronic digital Computers. ENIAC was 30‟x50‟ long and

weighs about 30 tons and having 18,000 Valves or vacuum tubes and about 6,000 switches.

This has been built in the Year 1942. EDVAC:- This is a computer built in the year 1950, after recognition of advantage Of binary digits.

EDVAC means Electronic Discrete Variable Automatic Computer.

EBCDIC:- This is an 8 bit code and used in IBM computers and IBM computable Computers.

EBCDIC means Extended Binary Coded Decimal Interchange Code.

E.g.:- A= 1100 0001 B= 1100 0010 Z= 1110 0111 1= 1111 0001 9= 1111 1001

ASCII:-

This means American Standard Code for Information Interchange. This was developed

to standardize codes of various data processing equipments And primarily used by Non-IBM

computer systems. Earlier it is a seven bit code With 3 bit zones partition, but later extended to

8 bit codes and denoted As ASCII – 8.

E.g.:- A – 1010 0001 B - 1010 0010 1 - 0101 0001 9 - 0101 1001.

MISCELLANEOUS Palm PC / Desktop is a personal information manager computer program for Microsoft Windows or Mac OS/Mac OS X and can be used alone or in combination with a Palm OS personal digital assistant. A Handheld PC, or H/PC for short, is a term for a computer built around a form factor which is smaller than any standard laptop computer. It is sometimes referred to as a Palmtop. The first handheld device compatible with desktop IBM personal computers of the time was the Atari Portfolio of 1989. Another early model was the Poqet PC of 1989 and the Hewlett Packard HP 95LX of 1991. Other DOS compatible hand-held computers also existed. Some Handheld PCs run on Microsoft's Windows CE operating system, with the term also covering Windows CE devices released by the broader commercial market.

Simputer : The Simputer is a self-contained, open hardware Linux-based handheld computer,

first released in 2002. Developed in, and primarily distributed within India, the product was

envisioned as a low-cost alternative to personal computers. With initial goals of selling 50,000

simputers, the project had sold only about 4,000 units by 2005, and has been called a failure by

news sources.

Modem A modem (modulator-demodulator) is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data. Modems can be used over any means of transmitting analog signals, from light emitting diodes to radio. The most familiar example is a voice band modem that turns the digital data of a personal computer into modulated electrical signals in the voice frequency range of a telephone channel. These signals can be transmitted over telephone lines and demodulated by another modem at the receiver side to recover the digital data.

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Webcam

A webcam is a video camera that feeds its images in real time to a computer or computer network, often via USB, ethernet, or Wi-Fi.

Their most popular use is the establishment of video links, permitting computers to act as videophones or videoconference stations. This common use as a video camera for the World Wide Web gave the webcam its name. Other popular uses include security surveillance and computer vision and there is also uses on sites like video broadcasting service and for recording social videos .

Webcams are known for their low manufacturing cost and flexibility, making them the lowest cost form of videotelephony. They have also become a source of security and privacy issues, as some built-in webcams can be remotely activated via spyware.

iPod is a line of portable media players created and marketed by Apple Inc. The product line-up currently consists of the hard drive-based iPod Classic, the touchscreen iPod Touch, the compact iPod Nano, and the ultra-compact iPod Shuffle. iPod Classic models store media on an internal hard drive, while all other models use flash memory to enable their smaller size (the discontinued Mini used a Microdrive miniature hard drive). As with many other digital music players, iPods can also serve as external data storage devices. Storage capacity varies by model, ranging from 2 GB for the iPod Shuffle to 160 GB for the iPod Classic. A digital camera (or digicam) is a camera that takes video or still photographs, or both, digitally by recording images via an electronic image sensor. It is the main device used in the field of digital photography. Most 21st century cameras are digital. Digital cameras can do things film cameras cannot: displaying images on a screen immediately after they are recorded, storing thousands of images on a single small memory device, and deleting images to free storage space. The majority, including most compact cameras, can record moving video with sound as well as still photographs. Some can crop and stitch pictures and perform other elementary image editing. Some have a GPS receiver built in, and can produce Geotagged photographs.

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COMPUTER LANGUAGES:- Computer languages are classified into 2 groups.

a) Low Level Languages(LLL):- This is also called as Machine languages, in this language

binary codes are Used, i.e., it uses the binary digits, “0” and”1”. This language is

understood by the Computer.

b) High Level Languages(HLL):- These languages are the written programmes using

English alphabets, number and special characters, symbols etc.,These languages are

not understood by the computers without an intermediator.

Following are the eg for HLL

a) BASIC - Beginners All Purpose Symbolic Instruction Code.

b) COBOL - Common Business Oriented Language.

c) FORTRAN - Formula Translation.

d) „C‟ / „C++‟ language , e) PASCAL f) ALGOL

e) 4GL - language used in the 4th generation computers are called as 4th generation

languages.

ASSEMBLER An assembler is a program that takes basic computer instructions and converts them into a pattern of bits that the computer's processor can use to perform its basic operations. Some people call these instructions assembler language and others use the term assembly language The programmer can write a program using a sequence of these assembler instructions. This sequence of assembler instructions, known as the source code or source program, is then specified to the assembler program when that program is started. The assembler program takes each program statement in the source program and generates a corresponding bit stream or pattern (a series of 0's and 1's of a given length).

An assembly language is a low-level programming language for computers, microprocessors,

microcontrollers, and other programmable devices. It implements a symbolic representation of the machine codes and other constants needed to program a given CPU architecture. This representation is usually defined by the hardware manufacturer, and is based on mnemonics that symbolize processing steps (instructions), processor registers, memory locations, and other language features. An assembly language is thus specific to a certain physical (or virtual) computer architecture. This is in contrast to most high-level programming languages, which, ideally, are portable.

A utility program called an assembler is used to translate assembly language statements into the target computer's machine code. The assembler performs a more or less isomorphic translation (a one-to-one mapping) from mnemonic statements into machine instructions and data. This is in contrast with high-level languages, in which a single statement generally results in many machine instructions. INTERPRETER Computer language processor that translates a program line-by-line (statement-by-statement) and carries out the specified actions in sequence. In contrast, an assembler or compiler completely translates a program written in a high-level language (the source program) into a machine-language program (the object program) for later execution. Whereas a compiled-program executes much faster than an interpreted-program, an interpreter allows examination and modification of the program while it is running (executing).

A program that executes instructions written in a high-level language. There are two ways to run programs written in a high-level language. The most common is to compile the program; the other method is to pass the program through an interpreter.

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An interpreter translates high-level instructions into an intermediate form, which it then executes. In contrast, a compiler translates high-level instructions directly into machine language. Compiled programs generally run faster than interpreted programs. The advantage of an interpreter, however, is that it does not need to go through the compilation stage during which machine instructions are generated. This process can be time-consuming if the program is long. The interpreter, on the other hand, can immediately execute high-level programs. For this reason, interpreters are sometimes used during the development of a program, when a programmer wants to add small sections at a time and test them quickly. In addition, interpreters are often used in education because they allow students to program interactively.

COMPILERS: These are the programmes used to compile or to convert HLL to LLL and vice

versa. A compiler is a computer program (or set of programs) that transforms source code written

in a programming language (the source language) into another computer language (the target language, often having a binary form known as object code). The most common reason for wanting to transform source code is to create an executable program. The name "compiler" is primarily used for programs that translate source code from a high-level programming language to a lower level language (e.g., assembly language or machine code). If the compiled program can run on a computer whose CPU or operating system is different from the one on which the compiler runs, the compiler is known as a cross-compiler. A program that translates from a low level language to a higher level one is a decompiler. A program that translates between high-level languages is usually called a language translator, source to source translator, or language converter. A language rewriter is usually a program that translates the form of expressions without a change of language.

A compiler is likely to perform many or all of the following operations: lexical analysis, preprocessing, parsing, semantic analysis (Syntax-directed translation), code generation, and code optimization. Program faults caused by incorrect compiler behavior can be very difficult to track down and work around; therefore, compiler implementors invest a lot of time ensuring the correctness of their software.The term compiler-compiler is sometimes used to refer to a parser generator, a tool often used to help create the lexer and parser.

TABLET PC A tablet computer (tablet PC), or simply tablet, is a mobile computer with display, circuitry and battery in a single unit. Tablets come equipped with sensors, including cameras, a microphone, an accelerometer and a touch

screen, with finger or stylus gestures substituting for the use of computer

mouse and keyboard. Tablets may include physical buttons (for example: to control basic features such as speaker volume and power) and ports (for network communications and to charge the battery). They usually feature on-screen, pop-up virtual keyboards for typing. Tablets are typically larger than smart phones or personal digital assistants at 7 inches (18 cm) or larger, measured diagonally. One can classify tablets into several categories according to the presence and physical appearance of keyboards. Slates and booklets do not have a physical keyboard and typically feature text input performed through the use of a virtual keyboard projected on a touch screen-enabled display. Hybrids and convertibles do have physical keyboards, although these devices typically also make virtual keyboards available

LAPTOP / NOTEBOOK A laptop or a notebook is a portable personal computer with a clamshell form factor, suitable for mobile use.[1] There was a difference between laptops and notebooks in the past, but nowadays it has gradually died away.[2] Laptops are commonly used in a variety of settings, including a work, an education, and a personal multimedia. A laptop combines the components and inputs of a desktop computer, including display, speakers, keyboard and pointing device (such as a touchpad or a trackpad) into a single device. Most modern-day laptop computers also have an integrated webcam and a microphone. A laptop can be powered either from a rechargeable battery, or

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by mains electricity via an AC adapter. Laptop is a diverse category of devices and other more specific terms, such as netbooks or rugged notebooks, refer to specialist types of laptops, which have been optimized for specific uses. Hardware specifications change significantly between different types, makes and models of laptops.

Desktop computer A desktop computer is a personal computer in a form intended for regular use at a single location desk/table due to its size and power requirements, as opposed to a laptop whose rechargeable battery and compact dimensions allow it to be regularly carried and used in different locations. The most common configuration is a computer monitor, keyboard and mouse, and a case that houses the main components of the PC, namely the power supply, motherboard, hard drive, optical drive, and previously the floppy drive. The form factor of the case is typically an upright tower or (horizontal) desktop. All-in-one computers, that integrate the monitor and main PC components in one unit, are often categorized under the desktop computer umbrella, particularly if they require an external power source and separate keyboard/mouse. The desktop category has also encompassed home

computers and workstations.

Computer Uses in Business and Office

Technology has forever changed the business world. In order to stay technically competitive and efficient in today’s information age, the majority of businesses now rely on computers. Computer uses in business range from the scanner at the checkout line of the grocery store to the ATM at the bank

1. Communication/networking The top computer uses in business include e-mail communication, and networking platforms such as video and web conferencing, social networking, and various other online chat tools. Even faxing, which has become increasingly obsolete in light of new technologies, is still a relevant business use of the computer. 2. Search engines and browsing Computers have provided us with instant access to a world of information. To stay competitive, businesses must utilize search engines such as Google or yahoo to obtain real time information and news and conduct research. 3. Financial transactions/e-commerce Retail purchases, credit card transactions, automatic debits… can all be processed over computers, and through the internet today. Banks, credit card companies, and other financial institutions are some of the best examples of computer uses in business. E-commerce is a rapidly growing industry, promising to become one of the top computer related professions in the future. 4. Storage, archival and retrieval Thousands and thousands of manuscripts, files, charts or other document types can be stored on a tiny microchip. In the old days, businesses needed file cabinets or warehouses to store pertinent records and data. Today, data management is easy, thanks to computers and computer products that enable businesses to organize, store, and easily retrieve critical information. 5. Design and presentation Just a few short decades ago, artists were still creating business documents by hand. The advent of graphic design, digital photography and printing technology has enabled businesses to display information more clearly and artistically. 6. Organization The ease with which databases, spreadsheets and data can be compiled on a computer has certainly improved the efficiency and management practices of businesses worldwide. Many offices now uses computer programs to handle scheduling, accounting, billing, inventory management, contact management, etc. 7. Document processing

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Word Processing, for letters, manuscripts, proposals, etc has revolutionized the business world. Today, many professionals would actually feel lost without simple editing tools such as spell check. 8. Telecommuting and remote business Portable laptop computers, smart phones, wireless internet, air cards and hub spots are the wave of the future when it comes to computer uses in business. Today, business can be conducted remotely from almost anywhere. 9. Marketing So much of marketing has gone online. Social media marketing, website development, blogging, advertising, e-newsletters have all become swift means of marketing in an increasingly globalized society. 10. E-learning, web-based training and software packages Electronically supported training programs are made possible by computers. Educational software, web training programs and virtual classrooms are all highly utilized in the business world, enabling professionals to learn new skills advance their careers. 11. Accounting Business success is dependent upon accuracy. Many businesses use accounting software and ledgering systems to ensure the accuracy of their financial status. 12. Websites and Advertising The combination of websites, advertising and marketing provide a swift means to vast business globalization. Websites make the company quickly available to everyone.

PEN DRIVE : (USB flash drive) A USB flash drive is a data storage device that includes flash

memory with an integrated Universal Serial Bus (USB) interface. USB flash drives are typically removable and rewritable, and physically much smaller than an optical disc. Most weigh less than 30 grams (1.1 oz). As of January 2013, drives of up to 512 gigabytes (GB) were available. A one-terabyte (TB) drive was unveiled at the 2013 Consumer Electronics Show and became available later that year. Storage capacities as large as 2 TB are planned, with steady improvements in size and price per capacity expected.[4] Some allow up to 100,000 write/erase cycles, depending on the exact type of memory chip used, and have a 10-year shelf storage time.

DVD / DVD-RW DVD (sometimes explained as "digital video disc" or "digital versatile disc"[4][5]) is a digital optical disc storage format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVDs can be played in multiple types of players, including DVD players. DVDs offer higher storage capacity than compact discs while having the same dimensions. A DVD-RW disc is a rewritable optical disc with equal storage capacity to a DVD-R, typically 4.7 GB (4,700,000,000 bytes). The format was developed by Pioneer in November 1999 and has been approved by the DVD Forum. The smaller Mini DVD-RW holds 1.46 GB, with a diameter of 8 cm.

The primary advantage of DVD-RW over DVD-R is the ability to erase and rewrite to a DVD-RW disc. According to Pioneer, DVD-RW discs may be written to about 1,000 times before needing replacement. DVD-RW discs are commonly used to store data in a non-volatile format, such as when creating backups or collections of files. They are also used for home DVD video recorders. One benefit to using a rewritable disc is if there are writing errors when recording data, the disc is not ruined and can still store data by erasing the faulty data.

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