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Computer is a device that receives Data (input), processes that Data , and display results (outputs) in form of information. Arvind.S.Baradhwaj Joies WHAT IS COMPUTER..?

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Arvind.S.Baradhwaj Joies

Generations of Computer:

In the beginning ... A generation refers to the state of improvement in the development of a product.  This term is also used in the different advancements of computer technology.  With each new generation, the circuitry has gotten smaller and more advanced than the previous generation before it.  As a result of the miniaturization, speed, power, and memory of computers has proportionally increased.  New discoveries are constantly being developed that affect the way we live, work and play. Generations of Computer

First Generation of Computer1946-1958 (The Vacuum Tube Years) :

The first generation computers were huge, slow, expensive, and often undependable.  In 1946 two Americans, Presper Eckert, and John Mauchly built the ENIAC electronic computer which used vacuum tubes instead of the mechanical switches of the Mark I.  The ENIAC used thousands of vacuum tubes, which took up a lot of space and gave off a great deal of heat just like light bulbs do.  The ENIAC led to other vacuum tube type computers like the EDVAC (Electronic Discrete Variable Automatic Computer) and the UNIVAC I (UNIVersal Automatic Computer). The vacuum tube was an extremely important step in the advancement of computers.  Vacuum tubes were invented the same time the light bulb was invented by Thomas Edison and worked very similar to light bulbs.  It's purpose was to act like an amplifier and a switch.  Without any moving parts, vacuum tubes could take very weak signals and make the signal stronger (amplifyit).  Vacuum tubes could also stop and start the flow of electricity instantly (switch).  These two properties made the ENIAC computer possible. The ENIAC gave off so much heat that they had to be cooled by gigantic air conditioners.  However even with these huge coolers, vacuum tubes still overheated regularly.  It was time for something new. First Generation of Computer 1946-1958 (The Vacuum Tube Years)

First Generation Computers:

First Generation Computers

The Second Generation:  1959-1964 (The Era of the Transistor) :

The transistor computer did not last as long as the vacuum tube computer lasted, but it was no less important in the advancement of computer technology.  In 1947 three scientists, John Bardeen , William Shockley , and Walter Brattain working at AT&T's Bell Labs invented what would replace the vacuum tube forever.  This invention was the transistor which functions like a vacuum tube in that it can be used to relay and switch electronic signals. There were obvious differences between the transisitor and the vacuum tube.  The transistor was faster, more reliable, smaller, and much cheaper to build than a vacuum tube.  One transistor replaced the equivalent of 40 vacuum tubes .  These transistors were made of solid material, some of which is silicon , an abundant element (second only to oxygen) found in beach sand and glass.  Therefore they were very cheap to produce.  Transistors were found to conduct electricity faster and better than vacuum tubes.  They were also much smaller and gave off virtually no heat compared to vacuum tubes.  Their use marked a new beginning for the computer.  Without this invention, space travel in the 1960's would not have been possible.  However, a new invention would even further advance our ability to use computers. The Second Generation: 1959-1964 (The Era of the Transistor)

Second Generation Computers:

Second Generation Computers

The Third Generation:  1965-1970 (Integrated Circuits - Miniaturizing the Computer) :

Transistors were a tremendous breakthrough in advancing the computer.  However no one could predict that thousands even now millions of transistors (circuits) could be compacted in such a small space.  The integrated circuit , or as it is sometimes referred to as semiconductor chip , packs a huge number of transistors onto a single wafer of silicon. Robert Noyce of Fairchild Corporation and Jack Kilby of Texas Instruments independently discovered the amazing attributes of integrated circuits.  Placing such large numbers of transistors on a single chip vastly increased the power of a single computer and lowered its cost considerably. Since the invention of integrated circuits, the number of transistors that can be placed on a single chip has doubled every two years, shrinking both the size and cost of computers even further and further enhancing its power.  Most electronic devices today use some form of integrated circuits placed on printed circuit boards-- thin pieces of bakelite or fiberglass that have electrical connections etched onto them -- sometimes called . These third generation computers could carry out instructions in billionths of a second.  The size of these machines dropped to the size of small file cabinets. Yet, the single biggest advancement in the computer era was yet to be discovered. The Third Generation: 1965-1970 (Integrated Circuits - Miniaturizing the Computer)

Third Generation Computer:

Third Generation Computer

The Fourth Generation:  1971-Today (The Microprocessor) :

The Fourth Generation: 1971-Today (The Microprocessor) This generation can be characterized by both the jump to monolithic integrated circuits(millions of transistors put onto one integrated circuit chip) and the invention of the microprocessor ( a single chip that could do all the processing of a full-scale computer ).  By putting millions of transistors onto one single chip more calculation and faster speeds could be reached by computers.  Because electricity travels about a foot in a billionth of a second, the smaller the distance the greater the speed of computers.   However what really triggered the tremendous growth of computers and its significant impact on our lives is the invention of the microprocessor.  Ted Hoff, employed by Intel (Robert Noyce's new company) invented a chip the size of a pencil eraser that could do all the computing and logic work of a computer.  The microprocessor was made to be used in calculators, not computers. It led, however, to the invention of personal computers, or microcomputers. It wasn't until the 1970's that people began buying computer for personal use.  One of the  earliest personal computers was the Altair 8800 computer kit.  In 1975 you could purchase this kit and put it together to make your own personal computer.  In 1977 the Apple  II was sold to the public and in 1981 IBM entered the PC ( personal computer ) market. Today we have all heard of Intel and its Pentium ® Processors and now we know how it all got started.  The computers of the next generation will have millions upon millions of transistors on one chip and will perform over a billion calculations in a single second.  There is no end in sight for the computer movement. The Fourth Generation: 1971-Today (The Microprocessor)

Fourth Generations of Computer:

Fourth Generations of Computer


1. Input: This is the process of entering data and programs in to the computer system. You should know that computer is an electronic machine like any other machine which takes as inputs raw data and performs some processing giving out processed data. Therefore, the input unit takes data from us to the computer in an organized manner for processing. 2. Storage: The process of saving data and instructions permanently is known as storage. Data has to be fed into the system before the actual processing starts. It is because the processing speed of Central Processing Unit (CPU) is so fast that the data has to be provided to CPU with the same speed. Therefore the data is first stored in the storage unit for faster access and processing. This storage unit or the primary storage of the computer system is designed to do the above functionality. It provides space for storing data and instructions. The storage unit performs the following major functions: All data and instructions are stored here before and after processing. Intermediate results of processing are also stored here. BASIC COMPUTER OPERATIONS

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3. Processing: The task of performing operations like arithmetic and logical operations is called processing. The Central Processing Unit (CPU) takes data and instructions from the storage unit and makes all sorts of calculations based on the instructions given and the type of data provided. It is then sent back to the storage unit. 4. Output: This is the process of producing results from the data for getting useful information. Similarly the output produced by the computer after processing must also be kept somewhere inside the computer before being given to you in human readable form. Again the output is also stored inside the computer for further processing. 5. Control: The manner how instructions are executed and the above operations are performed. Controlling of all operations like input, processing and output are performed by control unit. It takes care of step by step processing of all operations in side the computer.


FUNCTIONAL UNITS In order to carry out the operations mentioned in the previous section the computer allocates the task between its various functional units. The computer system is divided into three separate units for its operation. They are 1) arithmetic logical unit, 2) control unit, and 3) central processing unit.

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Arithmetic Logical Unit (ALU) After you enter data through the input device it is stored in the primary storage unit. The actual processing of the data and instruction are performed by Arithmetic Logical Unit. The major operations performed by the ALU are addition, subtraction, multiplication, division, logic and comparison. Data is transferred to ALU from storage unit when required. After processing the output is returned back to storage unit for further processing or getting stored. Control Unit (CU) The next component of computer is the Control Unit, which acts like the supervisor seeing that things are done in proper fashion. The control unit determines the sequence in which computer programs and instructions are executed. Things like processing of programs stored in the main memory, interpretation of the instructions and issuing of signals for other units of the computer to execute them. It also acts as a switch board operator when several users access the computer simultaneously. Thereby it coordinates the activities of computer’s peripheral equipment as they perform the input and output. Therefore it is the manager of all operations mentioned in the previous section. Central Processing Unit (CPU) The ALU and the CU of a computer system are jointly known as the central processing unit. You may call CPU as the brain of any computer system. It is just like brain that takes all major decisions, makes all sorts of calculations and directs different parts of the computer functions by activating and controlling the operations.


Computer hardware is the physical part of a computer , including the digital circuitry , as distinguished from the computer software that executes within the hardware. The hardware of a computer is infrequently changed, in comparison with software and data, which are "soft" in the sense that they are readily created, modified or erased on the computer. Firmware is a special type of software that rarely, if ever, needs to be changed and so is stored on hardware devices such as read-only memory (ROM) where it is not readily changed (and is, therefore, "firm" rather than just "soft"). Most computer hardware is not seen by normal users. It is in embedded systems in automobiles, microwave ovens, electrocardiograph machines, compact disc players, and other devices. Personal computers , the computer hardware familiar to most people, form only a small minority of computers (about 0.2% of all new computers produced in 2003). See Market statistics . Hardware

Typical PC Hardware:

Monitor Keyboard & Mouse Mother Board Power Supply Storage Controllers of IDE Video Display Controller Removable Media Writer Internal Storage Sound Card Typical PC Hardware

Cathode Ray Tubes (CRTs) :

Cathode Ray Tubes (CRTs) CRTs, or video monitors, are the most common output device on computers today. The figure below illustrates the basic structure of a CRT. A CRT is an evacuated glass bottle, with a heating element on one end and a phosphor coated screen on the other. When a current flows through this heating element, called a filament, the conductivity of the metal filamant is reduced due to the high temperature. This cause electrons to pile up on the filament, because they can not move as fast as they would like to (Notice I'm wearing my "electrons-are-particles" hat). Some of these electrons actually boil off of the filament. These free electrons are attracted to a strong positive charge from the outer surface of the focusing anode cylinder (sometines called an electrostic lens). However, the inside of the cylinder has a weaker negative charge. Thus when the electrons head toward the anode they are forced into a beam and accelerated by the repulsion of the inner cylinder walls in just the way that water is speeds up when its flow though a smaller diameter pipe. By the time the electrons get out they're going so fast that they fly past the cathode they were heading for.

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The next thing that the electrons run into are two sets of weakly charged deflection plates. These plates have opposite charges, one positive the other negative. While their charge is not strong enough to capture the fast moving electrons they do influence the path of the beam. The first set displaces the beam up and down, and the second displaces the beam left and right. The electrons are sent flying out of the neck of the bottle until they smash into the phosphor coating on the other end of the bottle. The impact of this collision on the out valence bands of the phosphor compounds knocks some of the electrons to jump into the another band. This causes a few photons to be generated, and results in our seeing a spot on the CRT's face CRTs were embraced as output devices very early in the development of digital computers. There close cousins, vacuum tubes, were some of the first switching elements used to build computers. Today, the CRT is a the last remaining vacuum tube in most systems (Even the flashing lights are solid-state LEDs). Most likely, oscilloscopes were some of the first computer graphics displays. The results of computations could be used to directly drive the vertical and horizontal displacement plates in order to draw lines on the CRT's face. By varying the current to the heating filament the output of the electron beam could also be controlled. This allowed the intensity of the lines to vary from bright to completely dark. These early CRT displays were called vector, calligraphic or affectionately stroker displays. The following demostration gives some feel for how they worked.

Color Video :

Color CRT's are more complicated than the simple monochrome models summarized above. The phosphors on the face of a color CRT are laid out in a precise geometric pattern. There are two primary variations, the stripe pattern of in-line tubes shown on the left, and the delta pattern of delta tubes as shown on the right. Within the neck of the CRT there are three electron guns, one each for red, green, and blue (the actual beams are all the same color-invisible). There is also a special metal plate just behind the phosphor cover front face, called a shadow mask. This mask is aligned so that it simultaneously allows each electron beam to see only the phosphors of its assigned color and blocks the phosphor of the remaining two colors. Color Video

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The figure shows the configuration of an example in-line tube. A significant portion of the electron beam's energy strikes the mask rather than the phosphors. This has two side effects. The shadow mask has to be extremely rigid to stay aligned with the phosphor patterns on the CRT face. The collision of electrons with metal mask causes the mask to emit some of it absorbed energy as eletromagnetic radiation. Most of this energy is in the form of heat, but some fraction is emitted as x-rays. X-rays can present a health hazard. This wasn't a large problem for television because the intensity of the x-ray radiation falls off quickly as you move away from the screen. However, computer monitors are supposed to be viewed from a short distance. This health concern along with the high voltages and power dispations of CRTs has motivated the development of new display technologies.


Arvind.S.Baradhwaj Joies Cabinet



Different types of Cabinet:

Different types of Cabinet


A keyboard is a set of typewriter-like keys that enables you, the user, to enter information and instructions into a computer . It contains …. Alphanumeric Keys : Letters and numbers Punctuation Keys : Comma, semicolon, etc. Special Keys : control keys, arrow keys, Caps Lock key, and so on . Function Keys: Num Pad: Number keys. Arvind.S.Baradhwaj Joies KEYBOARD


Arvind.S.Baradhwaj Joies Mouse Standard Two-Button: Left button for selecting, right button for properties Wheeled Mouse - Wheel for scrolling. Wireless mouse. Sensor mouse.


Printer Laser Printer Desk Jet Printer


I/O DEVICES Arvind.S.Baradhwaj Joies

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Motherboard: The main circuit board of a microcomputer. The motherboard contains the connectors for attaching additional the cpu, Bios, memory, mass storage boards. Typically, the motherboard contains interfaces, serial and parallel ports,expansion slots, and all the controllers required to control standard peripheral devices,  such as the display screen, keyboard,and disk drive. Collectively, all these chips that reside on the motherboard are known as the motherboard's chipset.

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Arvind.S.Baradhwaj Joies

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Arvind.S.Baradhwaj Joies

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Arvind.S.Baradhwaj Joies

Video Graphics Adapter:

Video Graphics Adapter

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What is a processor? The CPU or the Central Processing unit is the brain of the computer and the single most important chip in the computer. Modern processors contain millions of transistors which are etched onto a tiny square silicon called a die, which is about the with of a standard thumb. The CPU performs the system's calculating and processing. The majority of personal computers included the Intel processors. Intel released the first processor, the 4004 in 1970. Today the market is being shared by other companies such as the popular AMD processor manufactured by the AMD company.

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What is Ram or Memory? Although memory is technically any form of electronic storage, it is used most often to identify fast, temporary forms of storage. If your computer's Cpu had to constantly access the hard drive to retrieve every piece of data it needs, it would operate very slowly. When the information is kept in memory,the CPU can access it much more quickly. Most forms of memory are intended to store data temporarily. The primary storage is referred to as random access memory (RAM) because it is possible to randomly select and use any location of the memory directly store and retrieve data. It takes same time to any address of the memory as the first address. It is also called read/write memory. The storage of data and instructions inside the primary storage is temporary. It disappears from RAM as soon as the power to the computer is switched off. The memories, which loose their content on failure of power supply, are known as volatile memories So now we can say that RAM is volatile memory.

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What is a hard drive? The mechanism that reads and writes data on a hard disk. Hard disk drives (HDDs) for PCs generally have seek times of about 12 milliseconds or less. Many disk drives improve their performance through a technique called caching.

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What is a cpu fan? A cpu fan is a fan that cools the cpu. [go figure] Without the fan it will cause the cpu to overheat which in turn causes lockup problems.

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What is a power supply? A power supply is where you normally plug the power cord into. The unit converts 110 volts to 12 volts to supply the computer and its components power.

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What is a ribbon cable? The ribbon cable is what connects the hard-drive, cd rom, and floppy to the motherboard.

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42 Modem Modems accept digital data, and convert it to a modulated analog wave form that can be transmitted over a normal analog phone line. And conversely, modems also accept a modulated analog wave from the telephone line, convert it to a digital form, and pass it on.


Shafqat Ullah 56K MODEM

Floppy Disk:

Floppy Disk

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Shafqat Ullah


DVD stands for “Digital Versatile Disk” or “Digital Video Disk” DVD was first created just to be a bigger CD capable of holding more info A DVD disk can hold between 4.4 and 16gb of data, depending on the disk 46 DVD

Storing the Data:

Tracks are concentric circles, and Sectors are pie-shaped wedges on a tracks. A sector contains a fixed number of bytes – 512 bytes. low-level formatting a drive establishes the tracks and sectors on the platter. High-level formatting then writes the file-storage structures, like the file-allocation table, into the sectors. 47 Storing the Data Track Sector

CD - Rom Drives :

48 CD - Rom Drives


49 DVD

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External Bus Controllers - used to connect to external peripherals, such as printers and input devices. These ports may also be based upon expansion cards, attached to the internal buses. parallel port serial port USB firewire


Universal Serial Bus is an external bus that supports transfer rates of 12 Mbps, can support 127 devices and supports hot plugging. Arvind.S.Baradhwaj Joies USB

Parallel Port, Firewire & Serial Port:

Parallel Port, Firewire & Serial Port

Different Types of Computer:

Analog Computer Different Types of Computer

Digital Computer:

Digital Computer

Lap Top:

Lap Top

Computer with LCD Monitor:

Computer with LCD Monitor



Cray Computer:

Cray Computer

Super Computer:

Super Computer



Credits :

Special Thanks to Arvind.S.Baradhwaj Joies Presented by Joies Credits

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