Computer Hardware Note - PARADISE COMPUTER



Computer Hardware

Computer A programmable electronic device designed to accept data, performprescribed mathematical and logical operations at high speed, anddisplay the results of these operations. Mainframes, desktop andlaptop computers, tablets, and smartphones are some of the differenttypes of computers.

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Computer Hardware : All the physical parts of computer is called hardware. Which has certain shape and size or we can be touched them. Hardware helps to execute (operator) the software.

History Of Computer

1. Abacus : The abacus (plural abaci or abacuses), also called a counting frame, is a calculating tool that was in use in Europe, China and Russia, centuries before the adoption of the written Hindu–Arabic numeral system.[1] The exact origin of the abacus is still unknown. Today, abaci are often constructed as a bamboo frame with beads sliding on wires, but originally they were beans or stones moved in grooves in sand or on tablets of wood, stone, or metal.

2. Logarithm Tables : The Logarithm table was developed by a mathematician Jhon Naphirers Bonn in 1914 in Scotland to

do fast calculation.

3. Slide Rule : A slide rule, also known as a slide ruler or a slipstick, is an extremely complex ruler that functions as an analog computer. By sliding various components of the ruler to align with each other, a slide rule can compute products, roots, logarithms, and the result of trigonometric functions.

In the mid 1600s, the linear slide rule was invented by Reverend William Oughtred and the inner slide rule was invented by Robert Bissaker. Until the invention of the pocket calculator in the 1960s, the slide rule was used by virtually every scientist and mathematician in the world.

4. Pascaline : Alternatively known as the Pascal's Adder, Pascale, or Pascalene, Pascaline is a calculating machine developed by Blaise Pascal in 1642. The Pascaline was capable of adding, subtracting, and carrying 10's, 100's, and 1000's.

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5. Leibnitz Stepped Calculator : In 1671 the German mathematician-philosopher Gottfried Wilhelm von Leibniz designed a calculating machine called the Step Reckoner. (It was first built in 1673.) The Step Reckoner expanded on Pascal's ideas and did multiplication by repeated addition and shifting. Leibniz was a strong advocate of the binary system.

6. Analytical Engine : The analytical engine is a machine, first proposed by Charles Babbage(Known as the Father of computer) in 1837, that is considered to be the concept for the first general mechanical computer. The design featured an Arithmetic Logic Unit (ALU) and permitted basic programmatic flow control. It was programmed using punch cards (inspired by the Jacquard Loom. It also featured integrated memory. For these reasons, historians consider it to be the first design concept of a general-purpose computer.

7. Lady Augusta Ada Lovelace : was an English mathematician and writer, chiefly known for her work on Charles Babbage's proposed mechanical general-purpose computer, the Analytical Engine. She was the first to recognise that the machine had applications beyond pure calculation, and published the first algorithm intended to be carried out by such a machine. As a result, she is often regarded as the first to recognise the full potential of a "computing machine" and the first computer programmer.

8. Dr. Herman Hellerith : Herman Hollerith (1860-1929) was the inventor of the punched card tabulating machine-the precursor of the modern computer-and one of the founders of modern information processing. His machine was used to gather information for the 1890 census more efficiently. Hollerith's company later became part of International Business Machines (IBM).

9. Electro Mechanical Computer : MARK-I. It is the first electro-mechanical computer developed by Howard Aiken in 1937. The machine was 5ft long, 3ft wide and 8ft high and used in 18000 vacuum tubes. The machine took 1 second to perform 3 mathematical calculations.

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Types Of Computer

CLASSIFICATION OFCOMPUTER ON THE BASIS OF SIZE

1. Super Computer

2. Mainframe Computer

3. Mini Computer

4. Micro Computer

1. Super Computer : Super computer is one of the most powerful computers which is used to perform the complex calculations. They are the fastest computer which works in nanosecond even in a picosecond too. This computer is used for a special purpose. Usually, such computer uses parallel processors. Nowadays, the computing capability of a super computer is equal to that of 40,000 micro computers. Mostly super computers are used by government agencies. These computers are used in research and other operations where there is a huge numerical calculation. Different industries also use this huge computer for designing their products. It is also used in Hollywood movies for animation purposes. It requires large space and temperature control room. CRAY X-MP/24, NEC-500, PARAM, etc are some of the examples of a super computer. Today's super computers are designed by companies such as HP, IBM, Cray Inc.

2. Mainframe Computer : Mainframe computers are powerful multi-user computers capable of supporting many hundreds of users simultaneously. It is also large in size. This computer has slower processing speed than a super computer but faster than a mini and micro computer. It is designed for large-scale data processing and a huge amount of data storage. They are used in a big organization such as bank, insurance companies, airlines, railway reservation system, e-mail service providers, web hosting, etc. It needed a large area approximately 1000 sq.ft. It supports a large number of I/O terminals, more than 100 terminals.

In a mainframe, each user accesses the mainframe’s resources through a device called a terminal. Their terminals are attached to the mainframes to perform the different types of task in FIFO.

Dumb terminal and intelligent terminal are the two kinds of terminals. A dumb terminal is the input/output device that functions as a window into a computer located somewhere else. An intelligent terminal can perform some processing operations, but it usually does not have any storage.

IBM 1401, ICL 2950/10,CYBER 170, etc are some of the examples of mainframe computers.

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3. Mini Computer : Minicomputer is also a multi-user computer capable of supporting ten to hundreds of users simultaneously. Due to the smaller size and its cost compared to mainframe and a super computer, it got its name as a minicomputer. It is also known as midrange computer. Minicomputer can handle more input and output than a micro computer. It can support about 50 terminals and requires an area around 100 sq ft. This computer is useful for medium sized business, organizations, industries, universities and banks. It is cheap and easy to operate than a mainframe computer.

Prime 9755, VAX 7500, HCL, MAGNUM, CDC-1700, etc. are some of the examples of a mini computer.

4. Micro Computer : A computer which is based on a microprocessor is called microcomputer. They are small and single user computer. This computer has a keyboard for entering data, a monitor for displaying and a storage device for storing the data. It requires less area compared to other computers.

This computer consists of central processing unit and a single chip. It is mainly used in office, school, house, shop, etc. The smallest of this category are a laptop, notebook, palmtop and PDA. IBM PC, Apple/Macintosh, etc. are the examples of the microcomputer. The microcomputer is categorized as a non-portable and portable category.

Some of the examples of microcomputer are described below:

a) Desktop : The desktop computer is the kind of personal computer (PC), which is a common type of computer used by many people today. They are a non-portable computer.

The term “desktop computer” means the concept of such a computer actually sitting on top of a desk. A computer is known as “workstation” is actually a relatively powerful kind of desktop.

b) Laptop : A ‘laptop’ computer is a light, compact and portable PC. It contains a rechargeable battery. They also contain a built-in LCD monitor. It is a portable computer.

To make them as portable as possible; most laptops try to avoid any sort of cable or wire. In laptop, instead of a mouse, a trackpad is used. Instead of wired connection to a network or printer, ‘wireless’ radio connection are used.

A laptop is also known as a notebook, which is another kind of personal computer used by many people today. It has usually a flat-screen monitor and keyboard attached to the computer.

Types of Laptop :

i) Handheld : A handheld computer is a kind of portable computer that is intended to be held and used in a hand. A handheld computer is becoming more and more common in modern society.

This computer includes various kinds of PDA (Personal Digital Assistant) computers, such as those running palm OS or windows mobile. Nowadays, mobile phones have slowly replaced by smartphones and similar handhelds with mobile phone capabilities.

Those phones which contains the running of Google Android, windows mobile and also the iPhone are the handheld computer which has the function of mobile phones.

ii) PAD (Personal Digital Assistant): A PDA is similar to a palmtop computer. It is more compact and typically has no keyboard, using a touch screen for all data input. The screen of PDA has a small screen. So, it has a small stylus (plastic stick) that is used to press things on a screen.

Most PDAs use some sort of handwriting recognition system to allow the user to write on the screen and have their writing converted into text. PDAs use a ‘digital diaries’ to take their e-mail, documents, appointments, etc.

CLASSIFICATION OF COMPUTER ON THE BASIS OF WORK

i. Analog Computer

ii. Digital Computer

iii. Hybrid Computer

1)Hybrid Computer : The computer that work with natural phenomena and physical values like earthquake measurement, speed of the wind, weight light etc is known as Analog computers. It is especially used in scientific work, medical and industrial field. These are special purpose computers. It measures physical values such as temperature or pressure that fall along a continuous scale in temperature or pressure. For example, you can see a system on petrol pump that contains an analog processor and analog device that converts flow of petrol into quantity. Speedometer in cars and your watch are other examples of analog computer.

2) Digital Computer : A computer that work with digital value 0 and 1. Where 0 is OFF and 1 is ON. It works with discrete data. Digital computer does not measure the continuous data for continuous output. Most of the electronic system is based on the digital system. Digital computers are very popular for actual computers are very popular for actual computer works like preparation of the report, documentation, billing and other graphical work etc. The entire PC (Personal Computer) used today on different fields are digital computers.

3) Hybrid Computer : It is the combination of analog and digital computer system. It works with continuous and discrete value. The good qualities of analog and digital computers are combined on this computer and made the hybrid computer. These are used in ICU (Intensive Care Unit) of the hospital, jet planes, and other data analysis terminals. Hybrid computer transfers the data from analog to digital and digital to analog and vice-versa.

CLASSIFICATION OF COMPUTER ON THE BASIS OF BRAND

1. IBM PC (International Business Machine Personal Computer)

2. IBM Compatible

3. Apple/Macintosh

1) IMB PC: IBM is the largest computer manufacturing company established in 1924, in the USA. The IBM PCs are developed by a company named, International Business Machine (IBM) Company so, the computers are known as IBM PC. The technology used in IBM PC is designed by the engineer of IBM Company. IBM PCs are more reliable, durable and have better quality but costly. It was specifically designed for professionals and scientific problem solvers.

2) IBM Compatible : The computers that have some functional characteristics and principles of IBM computers are called IBM compatible. IBM compatible computers are developed by other companies than IBM companies using the technology of IBM PC. They are easily available and cheaper. Their parts are easily available in the market. They are also duplicate or assemble a computer. They are popular in the world.

3) Apple / Macintosh : All the computers manufactured by Apple Co-operation are known as Apple/Macintosh computer. It is a leading computer manufacturing company of USA. Apple computers are developed by Apple Co-operation which was established in the late 1970s in the USA. Apple computers are costlier than IBM computers.

CLASSIFICATION OF COMPUTER ON THE BASIS OF MODEL

i.XT (Extended Technology):When referring to a computer, XT is short for eXtended Technology and is the name of the IBM 5160 computer introduced on March 8, 1983. The XT was the first IBM computer with a hard drive (10 MB or 20 MB), a 5 1/4" floppy drive, up to 640 KB of memory, an Intel 8088 processor, an eight-bit ISA slot, and a serial port.

ii. AT (Advance Technology): Short for Advanced Technology, AT is an IBM computer first introduced in 1984. The base model AT computer contained an 80286 processor, 256 k of RAM and a 1.2 MB floppy disk drive. The AT was also available with 512 k of RAM and a 20 byte disk drive. Today, an AT-Class system is any computer with a 16-bit, 32-bit, or 64-bit system. Earlier computers (8-bit) were known as PC/XT-class systems. All new computers used today are considered AT-Class computers and you're not likely to encounter earlier computers. A PC/XT-class computer can be identified if it is using the older 8-bit ISA expansion slot.

iii.PS/2 (Personal System-2) :

The PS/2 architecture was quite different. It was designed to be compatible with the PC/XT/AT line of computers popular in the PC clone market. PS/2 architecture had 2 BIOSs (ABIOS and CBIOS) for additional security and compatibility and Micro Channel Architecture for superior bus communications speed. It included special connection ports for mouse and keyboards (still in use into the 21st-century, and called PS/2 interfaces) and incorporated a new frame buffer known as VGA (Video Graphics Array) which replaced the previous EGA (Enhanced Graphics Adapter) standard. PS/2 used the 15-pin mini-D connector for video out and used RGB signals allowing increases in color depth (i.e. increased levels of gray}. The PS/2 line was the first to use 3.5” floppy disks (common by 1987) as standard and introduced the 72-pin RAM SIMM which became the de facto standard for RAM by the mid-1990s.

Generation Of Computer

Five Generations of Computers Checklist

[pic] Getting Started: Key Terms to Know

[pic] First Generation: Vacuum Tubes 

[pic] Second Generation Transistors

[pic] Third Generation Integrated Circuits

[pic] Fourth Generation Microprocessors

[pic] Fifth Generation Artificial Intelligence

First Generation: Vacuum Tubes (1940-1956)

The first computers used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous, taking up entire rooms. These computers were very expensive to operate and in addition to using a great deal of electricity, the first computers generated a lot of heat, which was often the cause of malfunctions.

First generation computers relied on machine language, the lowest-level programming language understood by computers, to perform operations, and they could only solve one problem at a time. It would take operators days or even weeks to set-up a new problem. Input was based on punched cards and paper tape, and output was displayed on printouts.

The UNIVAC and ENIAC computers are examples of first-generation computing devices. 

Second Generation: Transistors (1956-1963)

The world would see transistors replace vacuum tubes in the second generation of computers. The transistor was invented at Bell Labs in 1947 but did not see widespread use in computers until the late 1950s. 

The transistor was far superior to the vacuum tube, allowing computers to become smaller, faster, cheaper, more energy-efficient and more reliable than their first-generation predecessors. Though the transistor still generated a great deal of heat that subjected the computer to damage, it was a vast improvement over the vacuum tube. Second-generation computers still relied on punched cards for input and printouts for output.

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Third Generation: Integrated Circuits (1964-1971)

The development of the integrated circuit was the hallmark of the third generation of computers. Transistors were miniaturized and placed on silicon chips, called semiconductors, which drastically increased the speed and efficiency of computers.

Instead of punched cards and printouts, users interacted with third generation computers through keyboards and monitors and interfaced with an operating system, which allowed the device to run many different applications at one time with a central program that monitored the memory. Computers for the first time became accessible to a mass audience because they were smaller and cheaper than their predecessors.

Fourth Generation:  Microprocessors (1971-Present)

The microprocessor brought the fourth generation of computers, as thousands of integrated circuits were built onto a single silicon chip. What in the first generation filled an entire room could now fit in the palm of the hand. The Intel 4004 chip, developed in 1971, located all the components of the computer—from the central processing unit and memory to input/output controls—on a single chip.

In 1981 IBM introduced its first computer for the home user, and in 1984 Apple introduced the Macintosh. Microprocessors also moved out of the realm of desktop computers and into many areas of life as more and more everyday products began to use microprocessors.

As these small computers became more powerful, they could be linked together to form networks, which eventually led to the development of the Internet. Fourth generation computers also saw the development of GUIs, the mouse and handheld devices.

Fifth Generation: Artificial Intelligence (Present and Beyond)

Fifth generation computing devices, based on artificial intelligence, are still in development, though there are some applications, such as voice recognition, that are being used today. The use of parallel processing and superconductors is helping to make artificial intelligence a reality. Quantum computation and molecular and nanotechnology will radically change the face of computers in years to come. The goal of fifth-generation computing is to develop devices that respond to natural language input and are capable of learning and self-organization.

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An Introduction to Hardware

Abbreviated as HW, Hardware is best described as any physical component of a computer system that contains a circuit board, ICs, or other electronics. A perfect example of hardware is the screen on which you are viewing this page. Whether it be a computer monitor, tablet or smartphone; it's hardware. Without any hardware, your computer would not exist, and software could not be used. The picture is a Logitech webcam, an example of an external hardware peripheral. This hardware device allows users to take videos or pictures and transmit them over the Internet. There are two types of Hardware : External hardware and Internal hardware .

External hardware examples:

Below is a list of external hardware or hardware that is found outside of your computer that may be found with a computer:

Flat-panel, Monitor, and LCD, Gamepad, Joystick, Keyboard, Microphone, Mouse, Printer, Projector, Scanner, Speakers, USB thumb drive.

Internal hardware examples:

Below is a list of internal hardware or hardware that is found inside your computer and may be found in a computer.

Processor (CPU), Drive (e.g., Blu-ray, CD-ROM, DVD, floppy drive, hard drive, and SSD), Fan (heat sink), Modem,

Motherboard, Network card, RAM, Sound card, Video card

Motherboard: The main board of computer is known as the mother board, which is located into the casing box. The motherboard is a printed circuit board that is the foundation of a computer, located on the back side or at the bottom of the computer chassis. It allocates power and allows communication to the CPU, RAM, and all other computer hardware components.

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Casing Box : A computer case, also known as a computer chassis, tower, system unit, cabinet, base unit, or simply case, is the enclosure that contains most of the components of a computer (usually excluding the display, keyboard and mouse). Cases are usually constructed from steel (often SECC—Steel, electrogalvanized, cold-rolled, coil) or aluminium. Plastic is sometimes used, and other materials such as glass, wood and even Lego bricks have appeared in home-built cases.

Power Supply (SMPS) : Short for Switched-Mode Power Supply, SMPS is a power supply that uses a switching regulator to control and stabilize the output voltage by switching the load current on and off. These power supplies offer a greater power conversion and reduce the overall power loss. A power supply unit (or PSU) converts mains AC to low-voltage regulated DC power for the internal components of a computer. Modern personal computers universally use switched-mode power supplies. Some power supplies have a manual switch for selecting input voltage, while others automatically adapt to the mains voltage.

Most modern desktop personal computer power supplies conform to the ATX specification, which includes form factor and voltage tolerances. While an ATX power supply is connected to the mains supply, it always provides a 5 Volt standby (5VSB) voltage so that the standby functions on the computer and certain peripherals are powered. ATX power supplies are turned on and off by a signal from the motherboard. They also provide a signal to the motherboard to indicate when the DC voltages are in spec, so that the computer is able to safely power up and boot. The most recent ATX PSU standard is version 2.31 of mid-2008.

UPS (Uninterruptible Power Supply) : Short for Uninterruptible Power Supply, UPS is a hardware device that provides a backup power source in case of a power outage (blackout), brownout, or a surge in power. A UPS provides enough power for a computer(s) to shut down properly or remain functional during the outage. There are three versions of the UPS: standby, on-line and line interactive. The picture shows an APC battery backup power strip.

Input Device :

An input device is any hardware device that sends data to a computer, allowing you to interact with and control it. he most commonly used or primary input devices on a computer are the keyboard and mouse. However, there are dozens of other devices that can also be used to input data into the computer. Such as ,

Trackball Joystick

Touch Screen Touch Pad

Scanner Micro Phone

Keyboard: A computer keyboard is one of the primary input devices used with a computer that looks similar to those found on electric typewriters, but with some additional keys. Keyboards allow you to input letters, numbers, and other symbols into a computer that can serve as commands or be used to type text.

Types Of Keyboard

(On the basis of Ports) 1. PS/2 Keyboard 2. USB Keyboard

PS/2 Keyboard USB Keyboard

Mouse : A computer mouse is a handheld hardware input device that controls a cursor in a GUI and can move and select text, icons, files, and folders. For desktop computers, the mouse is placed on a flat surface such as a mouse pad or a desk and is placed in front of your computer. The picture to the right is an example of a desktop computer mouse with two buttons and a wheel.

6 pin PS/2 specifications

|Pin |Voltage |Assignment |

|1 |+2.0 to +5.5v |Keyboard Data |

|2 |+4.8 to +5.5v |Reserved |

|3 |Ground |Ground |

|4 |+2.0 to +5.5v |+5.0V DC |

|5 |+2.0 to +5.5v |Keyboard Clock |

|6 |+2.0 to +5.5v |Reserved |

Output Device

An output device is any peripheral that receives data from a computer, usually for display, projection, or physical reproduction. In computing, an output device is a piece of computer hardware equipment that uses receive data and commands from an information processing system in order to perform a task. Such as:

1. Monitor

2. Printer

3. Speaker

Monitor : Monitor is Alternatively referred to as a video display terminal (VDT) and video display unit (VDU), a monitor is an output device that displays video images and text. A monitor is made up of circuitry, a screen, a power supply, buttons to adjust screen settings, and casing that holds all of these components. The monitor is the piece of computer hardware that displays the video and graphics information generated by the computer through the video card. Monitors are very similar to televisions but usually display information at a much higher resolution.

Types of Monitor

1. CRT (Cathode Ray Tube)

2. LCD (Liquid Crystal Display)

3. LED (Light-Emitting Diodes)

CRT (Cathode Ray Tube) Monitors:

These monitors employ the CRT technology used most commonly in the manufacturing of television screens. In this, a stream of intense high energy electrons is used to form images on a fluorescent screen. A cathode ray tube is a basically a vacuum tube containing an electron gun at one end and a fluorescent screen at another end. From this electron gun, a process called thermionic emission generates a strong beam of electrons. These electrons travel through a narrow path within the tube with high speed using various electro-magnetic devices and finally strike the phosphor points present on the fluorescent screen, thus creating an image. There are three types of CRT like Grayscale, Color and Digital. There are several advantages of using CRT monitors:

Features:

-These monitors are highly reliable and efficient, and are capable of generating a resolution of up to 2048 x 1536 pixels, thereby providing a clear picture quality. Also, CRT monitors that are now available are capable of producing thousands of different colors.

-Secondly, CRT monitors are affordable and cost effective.

-Unlike conventional CRT monitors, modern technological advancements have resulted in the development of flat screen CRT monitors that reduce the glare and are good for the eyes.

LCD (Liquid Crystal Display) Monitors

Liquid crystal display, also known as liquid crystal diode, is one of the most advanced technologies available at present. Typically, an LCD monitor consists of a layer of color or monochrome pixels arranged schematically between a couple of transparent electrodes and two polarizing filters. Optical effect is achieved by polarizing the light in varied amounts and making it pass through the liquid crystal layer. At present, there are two types of LCD technology available. These include the active matrix or TFT and a passive matrix technology. Among these, TFT technology is more secure and reliable, and generates better picture quality. On the other hand, passive matrix has a slow response time and is slowly becoming outdated.

In recent times, LCD monitors have become increasing popular with consumers. Some major advantages of using an LCD monitor include:

• These monitors are compact, lightweight, and do not consume much desk space.

• Secondly, these monitors do not consume much electricity and can even be operated by using batteries.

• Also, the images transmitted by these monitors do not get geometrically distorted and have little flicker.

LED (Light-Emitting Diodes) Monitors

LED monitors are the latest types of monitors in the market today. Like LCD, it is again a flat panel display making use of light-emitting diodes for back-lightning instead of Cold Cathode Fluorescent (CCFL) back-lightning used in LCDs. Primarily, the display is of LCD only but the back-lightning is done by LEDs.

LED monitors are said to use much lesser power than CRT and LCD. Thus, they are also considered environmental friendly. Other core advantages of LED monitors are:

1. They produce images with higher contrast

2. They have less negative environmental impact when disposed

3. Lifespan and durability of LED monitors is more than CRT or LCD monitors

4. Because of the technology, the monitor panels can be made very thin

5. Do not produce much heat while running

Printer : A printer is an external hardware output device that takes the electronic data stored on a computer or other device and generates a hard copy of it. For example, if you created a report on your computer you could print several copies to hand out at a staff meeting. Printers are one of the most popular computer peripherals and are commonly used to print text and photos. 

Types of Printer

1. Dot Matrix Printer : Dot Matrix  referred to as a pin printer, dot matrix printers were first introduced by IBM in 1957. However, the first dot matrix impact printer was created by Centronics in 1970. Dot matrix printers use print heads to shoot ink or strike an ink ribbon to place hundreds to thousands of little dots to form text and images. Today, dot matrix printers are utilized far less than they used to be due to their low quality images and slow print speed when compared to ink jet printers and laser printers. However, they still see a lot of use in certain sectors such as auto-part stores and package delivery companies.

2. Ink Jet Printer : The most popular printer for home computer users that prints by spraying streams of quick-drying ink on paper. The ink is stored in disposable ink cartridges, often a separate cartridge is used for each of the major colors. These colors are usually Black, Red/Magenta, Green/Cyan, and Yellow (CMYK). The picture is an example of a computer inkjet printer.

3. Laser Printer : The laser printer was first developed at Xerox PARC by Gary Starkweather and released in 1971 that utilizes laser technology to print images on the paper. Laser printers are often used for corporate, school, and other environments that require print jobs to be completed quickly and in large quantities. In the picture, is a Lexmark C782n laser printer and a good example of a laser printer. As the image shows, a laser printer is usually larger than an inkjet printer found in most homes.

4. Plotter : The plotter is a computer printer for printing vector graphics. In the past, plotters were used in applications such as computer-aided design, though they have generally been replaced with wide-format conventional printers. A plotter gives a hard copy of the output. It draws pictures on a paper using a pen.

Speaker : A computer speaker is a hardware device that connects to a computer to generate sound. The signal used to produce the sound that comes from a computer speaker is created by the computer's sound card. Speakers are one of the most common output devices used with computer systems. Some speakers are designed to work specifically with computers, while others can be hooked up to any type of sound system. Regardless of their design, the purpose of speakers is to produce audio output that can be heard by the listener.

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Memory Unit

Memory :Computer memory is any physical device capable of storing information temporarily or permanently. Computer memory is the storage space in the computer, where data is to be processed and instructions required for processing are stored. The memory is divided into large number of small parts called cells. By extension, computers have them also a short and long term memory. the long-term memory or nonvolatile memory contains programs and data the user wants to keep; these are stored on tapes, floppy disks or on ROM cards.The short-term memory or volatile memory, is located inside of the computer in the RAM chips and is used to store data only during his work. Soon as it is switched off voltage, even for a fraction of Second, the entire contents of the memory is lost instantly.

Types of Memory

1. Primary Memory (Volatile)

2. Secondary Memory (Non-Volatile)

Primary Memory : This memory is referred to as internal memory, main memory, main storage, and primary memory, a primary storage device is a medium that holds memory for short periods of time while a computer is running. Although it has a much lower access time and faster performance, it is also about two orders of magnitude more costly than secondary storage.

Types Of Primary Memory

1. RAM (Random Access Memory)

2. ROM (Read Only Memory)

RAM (Random Access Memory) : It is referred to as main memory, primary memory, or system memory, Random Access Memory (RAM) is a hardware device that allows information to be stored and retrieved on a computer. When you power off your computer the data stored in RAM is deleted, means volatile in nature. The RAM is a volatile memory, it means information written to it can be accessed as long as power is on. As soon as the power is off, it can not be accessed. so this mean RAM computer memory essentially empty. RAM holds data and processing instructions temporarily until the CPU needs it.

Types Of RAM

1.SDRAM(SynchronousDRAM)

Almost all systems used to ship with 3.3 volt, 168-pin SDRAM DIMMs. SDRAM is not an extension of older EDO DRAM but a new type of DRAM altogether. SDRAM started out running at 66 MHz, while older fast page mode DRAM and EDO max out at 50 MHz. SDRAM is able to scale to 133 MHz (PC133) officially, and unofficially up to 180MHz or higher. As processors get faster, new generations of memory such as DDR and RDRAM are required to get proper performance.

Note :1. DIMM :-Short for Dual In-line Memory Module, DIMM is a module containing a circuit board and one more random access memory chips. DIMMs have a 168-pin connector and, since the advent of the Pentium Processor, a 64-bit path. Because of the new bit path, DIMMs can be installed one at a time, unlike SIMMs that would require installation in pairs. SO-DIMM, which is short for Small Outline DIMM, is available in both a 72-pin and 144-pin configuration. SO-DIMMs are commonly utilized in laptop computers.

2.SIMM : Short for Single In-line Memory Module, SIMM is a memory module developed by Wang laboratories in 1983. The SIMM circuit board that holds six to nine memory chips per board, the ninth chip usually an error checking chip (parity or non parity). The SIMM was used with computers using a 486, early Intel Pentium, and compatible processors. However, because the Pentium is 64-bit and a SIMM is only 32-bits wide, they must be installed two at a time when used with any 64-bit processor.

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2.DDR (Double Data Rate SDRAM)

DDR basically doubles the rate of data transfer of standard SDRAM by transferring data on the up and down tick of a clock cycle. DDR memory operating at 333MHz actually operates at 166MHz * 2 (aka PC333 / PC2700) or 133MHz*2 (PC266 / PC2100). DDR is a 2.5 volt technology that uses 184 pins in its DIMMs. It is incompatible with SDRAM physically, but uses a similar parallel bus, making it easier to implement than RDRAM, which is a different technology.

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3.Rambus DRAM (RDRAM)

Despite it's higher price, Intel has given RDRAM it's blessing for the consumer market, and it will be the sole choice of memory for Intel's Pentium 4. RDRAM is a serial memory technology that arrived in three flavors, PC600, PC700, and PC800. PC800 RDRAM has double the maximum throughput of old PC100 SDRAM, but a higher latency. RDRAM designs with multiple channels, such as those in Pentium 4 motherboards, are currently at the top of the heap in memory throughput, especially when paired with PC1066 RDRAM memory.

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ROM (Read Only Memory) : Read-Only Memory, ROM is a storage medium that is used with computers and other electronic devices. As the name indicates, data stored in ROM may only be read. It is either modified with extreme difficulty or not at all. ROM is mostly used for firmware updates. A simple example of ROM is the cartridge used with video game consoles, which allows one system to run multiple games. ROM is a type of non-volatile memory used in computers and other electronic devices. Data stored in ROM can only be modified slowly, with difficulty, or not at all, so it is mainly used to store firmware (software that is closely tied to specific hardware, and unlikely to need frequent updates) or application software in plug-in cartridges.

There are five basic ROM types:

1.ROM.

2.PROM: Programmable read-only memory (PROM) is read-only memory ( ROM ) that can be modified once by a user. PROM is a way of allowing a user to tailor a microcode program using a special machine called a PROM programmer . This machine supplies an electrical current to specific cells in the ROM that effectively blows a fuse in them. The process is known as burning the PROM .

3.EPROM: Erasable programmable read-only memory is programmable read-only memory (programmable ROM) that can be erased and re-used.

4.EEPROM: electrically erasable programmable read-only memory) is user-modifiable read-only memory (ROM) that can be erased and reprogrammed (written to) repeatedly through the application of higher than normal electrical voltage. However, an EEPROM chip has to be erased and reprogrammed in its entirety, not selectively. It also has a limited life - that is, the number of times it can be reprogrammed is limited to tens or hundreds of thousands of times.

5.Flash memory: Flash memory is an electronic (solid-state) non-volatile computer storage medium that can be electrically erased and reprogrammed. Toshiba developed flash memory from EEPROM (electrically erasable programmable read-only memory) in the early 1980s and introduced it to the market in 1984. The two main types of flash memory are named after the NAND and NOR logic gates. The individual flash memory cells exhibit internal characteristics similar to those of the corresponding gates.

2. Secondary Memory : This is referred to as external memory, secondary memory, and auxiliary storage, a secondary storage device is a non-volatile device that holds data until it is deleted or overwritten. Secondary storage is about two orders of magnitude cheaper than primary storage. These are used for storing data/Information permanently. CPU directly does not access these memories instead they are accessed via input-output routines. Contents of secondary memories are first transferred to main memory, and then CPU can access it.

Main secondary memory are:

1. Magnetic Disk

2. Floppy Disk

3. Hard Disk

4. Optical Disks

Magnetic Disk: The Magnetic Disk is Flat, circular platter with metallic coating that is rotated beneath read/write heads. It is a Random access device; read/write head can be moved to any location on the platter. 

Floppy Disk These are small removable disks that are plastic coated with magnetic recording material. Floppy disks are typically 3.5″ in size (diameter) and can hold 1.44 MB of data. This portable storage device is a rewritable media and can be reused a number of times. Floppy disks are commonly used to move files between different computers. The main disadvantage of floppy disks is that they can be damaged easily and, therefore, are not very reliable. The following figure shows an example of the floppy disk. Figure 3 shows a picture of the floppy disk. 

Hard Disk : A hard disk drive (sometimes abbreviated as Hard drive, HD, or HDD) is a non-volatile memory hardware device that permanently stores and retrieves data on a computer. A hard drive is a secondary storage device that consists of one or more platters to which data is written using a magnetic head, all inside of an air-sealed casing. Internal hard disks reside in a drive bay, connect to the motherboard using an ATA, SCSI, or SATA cable, and are powered by a connection to the PSU (power supply unit).Another form of auxiliary storage is a hard disk. A hard disk consists of one or more rigid metal plates coated with a metal oxide material that allows data to be magnetically recorded on the surface of the platters. The hard disk platters spin at 5 a high rate of speed, typically 5400 to 7200 revolutions per minute (RPM).Storage capacities of hard disks for personal computers range from 10 GB to 2 TB (Terra Byte).

Optical Disks Optical Mass Storage Devices Store bit values as variations in light reflection. They have higher area density & longer data life than magnetic storage. They are also Standardized and relatively inexpensive. Their Uses: read-only storage with low performance requirements, applications with high capacity requirements & where portability in a standardized format is needed. 

Types of Optical Disk

1. CD-ROM (read only)

2. CD-R: (record) to a CD

3. CD-RW: can write and erase CD to reuse it (re-writable)

4. DVD(Digital Video Disk)

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|Primary memory |Secondary memory |

|1.Fast |1.Slow |

|2.Expensive |2.Cheap |

|3.Low capacity |3.Large capacity |

|4.Works directly with the processor |4.Not connected directly to the processor |

Measurement of Memory

The Processor :  A processor, central processor, or microprocessor, the CPU (pronounced sea-pea-you) is the Central Processing Unit of the computer. A computer's CPU handles all instructions it receives from hardware and software running on the computer. The CPU was first developed at Intel with the help of Ted Hoff and others in the early 1970's. The first processor released by Intel was the 4004 processor, shown in the picture to the right. This little chip is the heart of a computer. Also referred to as the "microprocessor," the processor does all the computations such as adding, subtracting, multiplying, and dividing. In PCs, the most popular microprocessor used is the Intel Pentium chip, whereas Macintosh computers use the PowerPC chip (developed by Motorola, IBM, and Apple).

The speed of a computer's processor is measured in megahertz, or cycles per second. But higher megahertz doesn't always mean better performance.

Types of Processor

AMD processors

|K6-2 |Sempron |Turion 64 |Phenom X3 |Athlon II |

|K6-III |Athlon 64 |Athlon 64 X2 |Athlon 6-series |E2 series |

|Athlon |Mobile Athlon 64 |Turion 64 X2 |Athlon 4-series |A4 series |

|Duron |Athlon XP-M |Phenom FX |Athlon X2 |A6 series |

|Athlon XP |Athlon 64 FX |Phenom X4 |Phenom II |A8 series |

| | | | |A10 series |

Intel processors

|4004 |Pentium |Pentium 4 |Pentium Extreme Edition |Core i3 |

|8080 |Pentium w/ MMX |Mobile Pentium 4-M |Core Duo |Core i5 |

|8086 |Pentium Pro |Pentium D |Core 2 Duo |Core i7 |

|8087 |Pentium II | | | |

|8088 |Celeron | | | |

|80286 (286) |Pentium III | | | |

|80386 (386) |Pentium M | | | |

|80486 (486) |Celeron M | | | |

The AMD Opteron series and Intel Itanium and Xeon series are CPUs used in servers and high-end workstation computers.

Some Terms Of Motherboard.

Resister : One of the most commonly found components in an electronic circuit. Resistors help restrict and impede a current flow. The picture shows examples of resistors on a motherboard. In this picture the resistors

are R92 and R93 and marked with 222.

Capacitor : A capacitor is a component made of two or sets of two conductive plates with a thin insulator between them and wrapped in a ceramic and plastic container. When the capacitor receives a direct current (DC), a positive charge builds up on one of the plates (or set of plates) while a negative charge builds up on the other. This charge, which is measured in microfarads on a computer capacitor, remains in the capacitor until it is discharged. In the image to the right, is an example of what a capacitor may look like on a computer motherboard.

 Inductor Coil: Short for electromagnetic coil, a coil is conductor wire such as copper in a cylindrical form around an iron core that creates an inductor or electromagnet to store magnetic energy. Coils are often used to remove power spikes and dips from power. The picture is an example of an inductor on a computer motherboard.

CPU Socket : A CPU socket or processor socket is a connection that allows a computer processor to be connected to a motherboard. For example, the Socket 370 is an example of such a socket. The picture shows an example of what a socket may look like on a motherboard. Although there have been computers that used the slot processor, most computers today and in the past have used socket processors.

CPU Fan : A heat sink is an electronic device that incorporates either a fan or a peltier device to keep a hot component such as a processor cool. There are two heat sink types: active and passive. Active heat sinks utilize the power supply and are usually a fan type or some other peltier cooling device. If you are looking to purchase an active heat sink, we recommend purchasing fans with ball-bearing motors that often last much longer than sleeve bearings. Sometimes these types of heat sinks are referred to as an HSF, which is short for heat sink and fan.

P4 Power Connector : The P4 connector is a 12V power supply cable used with motherboards that have an Intel Pentium 4 or later processor. Today, the connector is a standard power connector and is used with both Intel and AMD motherboards. As seen in the picture, the P4 cable has two black wires that serve as a ground and two yellow wires that are +12VDC and connect to a four pin connection on the motherboard.

Voltage Regulator : An integrated circuit that takes an unregulated power source and adjusts its voltage to a fixed level. For example, you could have 12V power source and using a voltage regulator, decrease that it to 5V. The picture shows an example of a voltage regulator on a computer motherboard.

Northbridge:  the northbridgeis an integrated circuit responsible for communications between the CPU interface, AGP, and the memory. Unlike the Southbridge the Northbridge is directly connected to these components and acts like a "bridge" for the Southbridge chip to communicate with the CPU, RAM, and graphics controller. Today, the northbridge is a single-chip that is North of the PCI bus, however, early computers may have had up to three separate chips that made up the northbridge.

Southbridge : The southbridge is an IC on the motherboard responsible for the hard drive controller, I/O controller and integrated hardware. Integrated hardware can include the sound card and video card if on the motherboard, USB, PCI, ISA, IDE, BIOS, and Ethernet.

24- pin Motherboard Power Connector : The ATX 24 pin 12V power supply connector can only be plugged in while pointing a specific direction on the motherboard. If you look carefully at the picture at the top of this page, you can see that the pins take a unique shape, a shape which the motherboard matches in only one direction.

The original ATX standard supported a 20 pin connector with a very similar pinout as the 24 pin connector but with pins 11, 12, 23, and 24 omitted. This means that the newer 24 pin power supply is useful for motherboards that require more power, and therefore eliminates the need for ATX 12V power supplies to provide an auxiliary power cable (although some still may).

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