fundamental of computer-u-1-computer hardware system

Computer Hardware SyStem

Course: BCA

Subject: Fundamental of Computer

Unit: I

History of Computers• Charles Babbage - father of computer

– 1800’s planned analytical engine

• ENIAC - developed at end of WW II

• 1951 - 1963 1st and 2nd generation

– very large, used unreliable vacuum tubes

• 1963 - present - 3rd and 4th generation

– smaller, faster - use transistors and integrated circuits

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History - Microcomputers

• Apple

– First sold in late 1970’s

– Developed by Jobs and Wozniak

• IBM Personal Computers

– First sold in 1981

– Was quickly accepted by businesses

– IBM compatibles soon developed

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What Is a Computer?

• A computer is an electronic device that accepts data and instructions from a user, manipulates the data according to the instructions, displays the information in some way, and stores the information for retrieval later

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What is a computer?

• An electronic device that accepts input, processes the data and

instructions, produces output from the processing that is useful

and meaningful and stores the results for future use.

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How Does A Computer Know What To Do?

• It must be given a detailed set of instructions that tell it exactly what to do.

• These instructions are called a computer program, or software.

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Generation of ComputerGeneration of Computer

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Index

1st Generation Of Computer

2nd Generation Of Computer

3rd Generation Of Computer

4th Generation Of Computer

5th Generation Of Computer

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Introduction

The term Computer Generation is after use in relation to the hard were of computer. Each phase of computer development is known as separate generation of computer. Each phase of development is characterized by type of switching circuits it utilizes.

Most computer today use the idea of stored program. Computer that was proposed by Dr.John Von Neumann in 1945.The Von Neumann architecture is based in three key concept that are:

1)Data & instruction (program) are stored in a single read write memory.

2)The memory content are addressable by location.3)Excution takes place in sequential fashion.

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First Generation [1949-55]

• The first generation of computer used the vaccume tube & machine language was used for giving instruction. The first generation computer used the concept ‘stored program'. The computer of this generation were very large in size & their programming was a difficult task.

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Some computer of this generation are given below:

• ENIAC :-It has very small memory & it was used for calculating trajectories of missiles.

• EDVAC:-The “Von Newmann” concept of stored program, was also applied in EDVAC.

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Some key feature of first generation:

• Used vacuumed tubes.

• Big computers.

• Electrically consumption high.

• Large Ac’s were necessary because the computer

generated heat.

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The Second Generation 1956-65

• The second generation computer began with the advent transistorized circuitry, invention of magnetic core & development of magnetic disk storage devicer.These new development made these computer more reliable. These Industries in the application’s like Marketing, Production planning etc.

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Some key feature of second generation:

• Transistor replaced vaccume tubes.

• Small in size.

• Less amount of heat was generated.

• Core memory was developed.

• First operating system was developed.

• Programming was in machine language as well as assembly language.

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The Third Generation[1966-1975]

The third generation of computer replaced transister with ‘Integrated circuits’ popularly known as chips. The IC was inverted by Jack kilby at Texas Instrument in 1958.The third generation computer using integrated circuit Proved to be highly reliable,relatively expensive & faster.

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Some key feature of third generation:

• Integrated circuits developed.

• Power consumption was low.

• Computer were smaller, faster & more reliable.

• High level languages (HLL) appeared.

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The Forth Generation[1976-Present]

• The advent of the microprocessor chip marked the beginning of the fourth generation computer. Very Large Scale Integrated (VLSI) circuits packing about 50,000 transistor in a chip. The Hard disks are also available of the size up to 80 GB.For larger disks RAID technology give to storage hundreds of GB. The CD ROM also becoming popular day by day. The CD ROM of today can store up to 650 MBS information.

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Some key features of forth generation:

• Integrated circuits smaller & faster.

• Portable computer developed.

• Great development in data communication.

• Different types of secondary memory with high storage

capacity & fast access developed.

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The Fifth Generation[Coming Generation]

Fifth Generation computing devices based on artificial intelligence, are still in development. The goal of fifth generation computing is to develop devices that response to natural language input & are capable of learning & self organization.

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Some key features of fifth generation:

• Parallel Processing was done.• Super conductors were used.• Many processors are grouped to function as one large group

processor.• A super conductor is a conductor through which electricity

can travel without any resistance resulting in faster transfer of information between the components of computer.

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The CPU

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The CPU

• Converts data into information

• Control center

• Set of electronic circuitry that executes stored program instructions

• Two parts– Control Unit (CU)

– Arithmetic Logic Unit (ALU)

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Control Unit CU

• Part of the hardware that is in-charge

• Directs the computer system to execute stored program instructions

• Communicates with other parts of the hardware

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Arithmetic / Logic UnitALU

Performs arithmetic operations

Performs logical operations

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Arithmetic Operations

Addition

Subtraction

Multiplication

Division

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Logical Operations

• Evaluates conditions

• Makes comparisons

• Can compare– Numbers

– Letters

– Special characters

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Basic Logic Gates

• A gate is a device that performs a basic operation on electrical signals

• Gates are combined into circuits to perform more complicated tasks

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Computers and Electricity

• There are three different, but equally powerful, notational methods for describing the behavior of gates and circuits– Boolean expressions

– logic diagrams

– truth tables

4–28

Computers and Electricity

• Boolean algebra: expressions in this algebraic notation are an elegant and powerful way to demonstrate the activity of electrical circuits

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Computers and Electricity

• Logic diagram: a graphical representation of a circuit

– Each type of gate is represented by a specific graphical symbol

• Truth table: defines the function of a gate by listing all possible input combinations that the gate could encounter, and the corresponding output

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Gates

• Let’s examine the processing of the following four types of gates

– NOT

– AND

– OR

– XOR

• Typically, logic diagrams are black and white, and the gates are distinguished only by their shape

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NOT Gate

• A NOT gate accepts one input value and produces one output value

Figure Various representations of a NOT gate

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NOT Gate

• By definition, if the input value for a NOT gate is 0, the output value is 1, and if the input value is 1, the output is 0

• A NOT gate is sometimes referred to as an inverter because it inverts the input value

4–33

AND Gate

• An AND gate accepts two input signals

• If the two input values for an AND gate are both 1, the output is 1; otherwise, the output is 0

Figure Various representations of an AND gate 34

OR Gate

• If the two input values are both 0, the output value is 0; otherwise, the output is 1

Figure Various representations of a OR gate35

XOR Gate

• XOR, or exclusive OR, gate

– An XOR gate produces 0 if its two inputs are the same, and a 1 otherwise

– Note the difference between the XOR gate and the OR gate; they differ only in one input situation

– When both input signals are 1, the OR gate produces a 1 and the XOR produces a 0

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XOR Gate

Figure Various representations of an XOR gate

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Presentation OnComputer Memory

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What is Memory ?

As the word implies “memory” means the place where we have to store any thing, this is very essential part of human being just like this memory is also very important for computer system because in computer system we have to store some data or information and for storing these items we need some memory or space.

So that’s why we can say that memory is very important part of computer system.

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About Memory

There are various units which are used to measure computer memory

• Bit - Smallest unit of computer memory

• Byte - 8 bit = 1 byte

• Kilobyte - 1024 byte = 1 kb

• Megabyte - 1024 kb = 1 mb

• Gigabyte - 1024 mb = 1 gb

• Terabyte - 1024 gb = 1 tb

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Memory are classified into two types :-

1. Primary Memory :-

Primary memory also known as “main memory” or “internal memory” which is located in the mother board of system or as we say which is directly connected to the CPU. It is the place where only little bit of data are stored either by manufacturer or by user.

This is further divided into two parts :- RAM ROM

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RAM

RAM also known as “random access memory” it stores the data which the user currently uses or as we say it stores the data temporary in it. RAM needs power or electricity to work when the computer power is turned off then all the data in it will be erased automatically.

This is a circuit which have its separate space or slot in motherboard. This allows the computer to run the software faster.

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ROM

Known as “Read Only Memory” as the word refers mainly it can only read the data which in stored in it. This memory is mainly used by our computer when we just turn on our computer. It contains BIOS of system. This is non-volatile in nature.

Mainly there are three types of ROM :-PROMEPROMEEPROM

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PROM

Known as “programmable Read Only memory”. In this when the data is stored then we have no right to change or alter any data to it. In this the data is written by Manufacturer company, even you can also purchase blank PROM chip but it can be programmed by special tool such as PROM programmers. In general PC’s mainly PROM is used because we don’t have to alter any data to it

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EPROM

Known as “Erasable PROM” as the word refers “erasable” means we can change or erase the data. So in EPROM we have right to change the data. In this we can change the data with the help of ultra violet rays. EPROM is much expensive than PROM.

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EEPROM

Known as “Electrically Erasable PROM” the type of ROM which can be erased by electrical charges. EEPROM can be erased one byte at anytime rather than erasing the entire chip by ultra violet rays.

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Secondary Memory The place where we store our personal data in computer system is

known as SM. In this we store data so that when the data is needed we can easily retrieve it. This is the fundamental component of comp. system. It is non volatile in nature so that we can not loose the data when power supply is off.

There are two methods for accessing the data from it :-

1. Sequential – This is the method in which we search the data sequentially or line by line until you find the desired data. E.g.. Magnetic tape, etc.2. Direct – This is the method in which computer can go directly to the information that the user wants.e.g. magnetic disk, optical disk, etc.

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Now I am going to discuss some of the secondary storage devices :-

1.Magnetic Tape :- Magnetic tape appears similar to the tape used in music cassettes. It is a plastic tape with magnetic coating. Mainly it is used to store music, movie, etc. it is not used to store data in it because as we know it comes under sequential access and it reads data line by line so that we can’t find the exact location of data.

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2. Magnetic Disk :- This is widely used popular storage medium for direct access secondary storage. This is the place where data are automatically save when we click on save button. It is non- volatile so that once data is stored in it will not lost when power goes off. This is the storage device where we mainly store or install OS for system.

Some of the magnetic disk are as follows :-

Hard DiskFloppy Disk, etc.

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Hard Disk

Hard Disk also known as “Hard Drive” or “Fixed Drive”. This is the place where we store our data or information so that we can retrieve for further use. This is the place where we install our OS so that we can run our computer. Hard disk comes fix in our system and if you require more hard disk then it comes in removable also. The average computer today comes with a 250 to 500 gb hard drive.

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Floppy Disk

This is removable, round, flat piece of Mylar plastic, coated with a ferric oxide. this kind of disk is read and written by Floppy Disk Drive (FDD), which is a device which performs basic operations on disk including reading and writing of data to it. This was used to transfer data from one computer to another. Earlier 5 ¼” floppy disks were used but these disks have less storage capacity so new format of 3 1/2” floppy disk came in market. Now a days floppy disk are not used because off less storage and high rate.

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Optical Disk

This is the secondary storage medium in which you can store much more data in it. This is flat, circular, plastic disk coated with material. Optical disk is very popular because of its small size and huge storage capacity. You must have optical disk reader in your computer so that you can read or write data on it.

There are two types of optical disk :-

1. CD

2. DVD

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CD

Known as “Compact Disk”, mainly used to store data, music, movie, software, etc. it can store 80 minutes of continues video recording. The space of CD is up to 700 mb. Due to its high storage capacity it is widely used. The data are store in it is in the form of “Pitts”. To avail the services of CD your computer should have CD drive.There are two types of CD :-1. CD ROM.2. CD R/W.

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DVD

Known as “Digital Versatile Disk”. It is high capacity storage medium. Mainly used to store movie, music, software, etc. the storage capacity of DVD is up to 4.7 gb. It looks similar to CD but due to its high storage capacity it is not cheaper as CD. To avail the facility of DVD you must have DVD drive in your computer. DVD drive also gives you facility to run CD disks too.

Types of DVD :-

1. DVD ROM.

2. DVD R/W. 54

What Is An Input Device ?

Entering data or instructions into a computer is called input. Therefore, an input device is a device which enters data or instructions into a computer.

Input devices are necessary to convert data into a form which can be understood by computers.

Some input devices are:

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The Mouse

This input device controls the cursor on the computer screen. It has two or three buttons and a cable connecting it to the computer. It is quite easy to operate a mouse, the user simply moves the cursor along the table. Once the cursor is at the desired location, the user can give instructions to the computer by clicking the button.

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The Joystick

A joystick looks like a stick fixed onto a box. It controls the cursor on the screen, so we can say it is alternate to the mouse.

The Keyboard Keyboards come in different shapes and sizes

depending on the type of brand. They are similar to typewriters.

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The Scanner

This looks like a photocopying machine, its function is to scan any document placed on its flat glass and send the contents to the computer.

The Bar Code Reader The black and white lines printed on certain products

which represent information like the country of origin, the price of it etc are bar codes. They can be read by a bar code reader which are commonly used in Supermarkets and shops.

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What is an Output device?

The information we get from the computer is known as output. The computer presents this information through these devices such as:

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The Monitor The monitor is one of the most important output devices, it is

used to display text and pictures. The monitor is also known as the Visual Display Unit (VDU)

The PrinterThere are several types of printers, some are:• Dot matrix- Consists of a print head with a number of pins

which move in and out to print in the form of dots.• Ink- jet- Consists of a print head with a number of tiny nozzles

and colored ink to form tiny dots.• Laser- Prints images by transferring ‘ ink powder’ onto a piece

of paper using a laser beam.

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The Plotter A plotter produces its output using special pens across

the paper to create a drawing. Engineers, architects and designers use plotters to produce their drawings or designs.

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REFERENCE

Reference Books

1. Information Technology for Managers By George Reynolds

2. Introduction to Computers by Gary Shelly, Steven Freund, Misty Vermaat

3. Introduction To Computers (Sie) By Norton

Image Reference

1. https://www.google.co.in/search?hl=en-IN&biw=1517&bih=714&noj=1&tbm=isch&sa=1&q=computer+i%2Fo+devices&oq=computer+i%2Fo+&gs_l=img.3.0.0j0i24l5.2236.7163.0.8878.9.8.0.1.1.0.301.1514.0j2j4j1.7.0.msedr...0...1c.1.60.img..1.8.1520.-wBpNhmwnZQ

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