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USB Cable

In information technology, Universal Serial Bus (USB) is a serial bus standard to connect devices to a host computer. USB was designed to allow many peripherals to be connected using a single standardized interface socket and to improve plug and play capabilities by allowing hot swapping; that is, by allowing devices to be connected and disconnected without rebooting the computer or turning off the device. Other convenient features include providing power to low-consumption devices, eliminating the need for an external power supply; and allowing many devices to be used without requiring manufacturer-specific device drivers to be installed.

USB is intended to replace many varieties of serial and parallel ports. USB can connect computer peripherals such as mice, keyboards, PDAs, gamepads and joysticks, scanners, digital cameras, printers, personal media players, flash drives, and external hard drives. For many of those devices, USB has become the standard connection method. USB was designed for personal computers, but it has become commonplace on other devices such as PDAs and video game consoles, and as a power cord between a device and an AC adapter plugged into a wall plug for charging. As of 2008[update], there are about 2 billion USB devices sold per year, and about 6 billion total sold to date.[1]

The design of USB is standardized by the USB Implementers Forum (USB-IF), an industry standards body incorporating leading companies from the computer and electronics industries. Notable members have included Agere (now merged with LSI Corporation), Apple Inc., Hewlett-Packard, Intel, Microsoft and NEC.

DSL Modem

ADSL modem or DSL modem is a device used to connect a single computer or router to a DSL phone line, in order to use an ADSL service. Like other modems it is a type of transceiver. It is also called a DSL Transceiver or ATU-R. The acronym NTBBA (network termination broad band adapter, network termination broad band access) is also common in some countries.

Some ADSL modems also manage the connection and sharing of the ADSL service with a group of machines: in this case, the unit is termed a DSL router or residential gateway. DSL routers have a functional block which performs framing, while other functional blocks perform Asynchronous Transfer Mode Segmentation and Reassembly, IEEE 802.1D bridging and/or IP routing. Typical user interfaces are Ethernet and USB. Although an ADSL modem working as a bridge does not need an IP address, it may have one assigned for management purposes.

Sound Card

A sound card (also known as an audio card) is a computer expansion card that facilitates the input and output of audio signals to and from a computer under control of computer programs. Typical uses of sound cards include providing the audio component for multimedia applications such as music composition, editing video or audio, presentation, education, and entertainment (games). Many computers have sound capabilities built in, while others require additional expansion cards to provide for audio capability.

Sound cards usually feature a digital-to-analog converter, which converts recorded or generated digital data into an analog format. The output signal is connected to an amplifier, headphones, or external device using standard interconnects, such as a TRS connector or an RCA connector. If the number and size of connectors is too large for the space on the backplate the connectors will be off-board, typically using a breakout box, or an auxiliary backplate. More advanced cards usually include more than one sound chip to provide for higher data rates and multiple simultaneous functionality, eg between digital sound production and synthesized sounds (usually for real-time generation of music and sound effects using minimal data and CPU time). Digital sound reproduction is usually done with multi-channel DACs, which are capable of multiple digital samples simultaneously at different pitches and volumes, or optionally applying real-time effects like filtering or distortion. Multi-channel digital sound playback can also be used for music synthesis when used with a compliance, and even multiple-channel emulation. This approach has become common as manufacturers seek to simplify the design and the cost of sound cards.

CD-Writer

n computing, an optical disc drive (ODD) is a disk drive that uses laser light or electromagnetic waves near the light spectrum as part of the process of reading or writing data to or from optical discs. Some drives can only read from discs, but recent drives are commonly both readers and recorders. Recorders are sometimes called burners or writers. Compact discs, DVDs and Blu-ray discs are common types of optical media which can be read and recorded by such drives.

Optical disc drives are an integral part of stand-alone consumer appliances such as CD players, DVD players and DVD recorders. They are also very commonly used in computers to read software and consumer media distributed in disc form, and to record discs for archival and data exchange. Optical drives—along with flash memory—have mostly displaced floppy disk drives and magnetic tape drives for this purpose because of the low cost of optical media and the near-ubiquity of optical drives in computers and consumer entertainment hardware.

Disc recording is generally restricted to small-scale backup and distribution, being slower and more materially expensive per unit than the moulding process used to mass-manufacture pressed discs.

VGA card

The term Video Graphics Array (VGA) refers specifically to the display hardware first introduced with the IBM PS/2 line of computers in 1987,[1] but through its widespread adoption has also come to mean either an analog computer display standard, the 15-pin D-subminiature VGA connector or the 640×480 resolution itself. While this resolution has been superseded in the personal computer market, it is becoming a popular resolution on mobile devices.[citation needed]

Video Graphics Array (VGA) was the last graphical standard introduced by IBM that the majority of PC clone manufacturers conformed to, making it today (as of 2009) the lowest common denominator that all PC graphics hardware supports, before a device-specific driver is loaded into the computer. For example, the MS-Windows splash screen appears while the machine is still operating in VGA mode, which is the reason that this screen always appears in reduced resolution and color depth.

VGA was officially superseded by IBM's XGA standard, but in reality it was superseded by numerous slightly different extensions to VGA made by clone manufacturers that came to be known collectively as "Super VGA".

Computer ports

In computing, a serial port is a serial communication physical interface through which information transfers in or out one bit at a time (contrast parallel port).[1] Throughout most of the history of personal computers, data transfer through serial ports connected the computer to devices such as terminals and various peripherals.

While such interfaces as Ethernet, FireWire, and USB all send data as a serial stream, the term "serial port" usually identifies hardware more or less compliant to the RS-232 standard, intended to interface with a modem or with a similar communication device.

For its use to connect peripheral devices the serial port has largely been replaced by USB and Firewire. For networking, it has been replaced by Ethernet. For console use with terminals (and then graphics) it was replaced long ago by MDA and then VGA. While nearly every server has a serial port connector, most non-poweruser workstations and laptops do not have a outwardly wired one as it is a legacy port, and superseded for most uses. Serial ports are commonly still used in legacy applications such as industrial automation systems, scientific analysis, shop till systems and some industrial and consumer products. Network equipment (such as routers and switches) often use serial console for configuration. Serial ports are still used in these areas as they are simple, cheap and their console functions (RS-232) are highly standardized and widespread.

The vast majority of computer systems have a serial port, however it must usually be wired manually and sometimes there are no pins in the manufactured version.

Power Supply

A power supply unit (PSU) is the component that supplies power to a computer. More specifically, a power supply is typically designed to convert 100-120 V (North America and Japan) or 220-240 V (New Zealand, Europe, South America, Africa, Asia and Australia) AC power from the mains to usable low-voltage DC power for the internal components of the computer. Some power supplies have a switch to change between 230 V and 115 V. Other models have automatic sensors that switch input voltage automatically, or are able to accept any voltage between those limits.

Most computer power supplies are a square metal box, and have a large bundle of wires emerging from one end. Opposite the wire bundle is the back face of the power supply, with an air vent and C14 IEC connector to supply AC power. There may optionally be a power switch and/or a voltage selector switch. A label on one side of the box lists technical information about the power supply, including safety certifications maximum output power. Common certification marks for safety are the UL mark, GS mark, TÜV, NEMKO, SEMKO, DEMKO, FIMKO, CCC, CSA, VDE, GOST R and BSMI. Common certificate marks for EMI/RFI are the CE mark, FCC and C-tick. The CE mark is required for power supplies sold in Europe and India.

Computer fans

A computer fan is any fan inside a computer case used for cooling purposes, and may refer to fans that draw cooler air into the case from the outside, expel warm air from inside, or move air across a heatsink to cool a particular component. The use of fans to cool a computer is an example of active cooling.

As processors, graphics cards, RAM and other components in computers have increased in clock speed and power consumption, the amount of heat produced by these components as a side-effect of normal operation has also increased. These components need to be kept within a specified temperature range to prevent overheating, instability, malfunction and damage leading to a shortened component lifespan.

While in earlier personal computers it was possible to cool most components using natural convection (passive cooling), many modern components require more effective active cooling. To cool these components, fans are used to move heated air away from the components and draw cooler air over them. Fans attached to components are usually used in combination with a heatsink to increase the area of heated surface in contact with the air, thereby improving the efficiency of cooling.

Graphic Card

A video card, also known as a graphics accelerator card, display adapter, or graphics card, is an expansion card whose function is to generate and output images to a display. Some video cards offer added functions, such as video capture, TV tuner adapter, MPEG-2 and MPEG-4 decoding, FireWire, light pen, TV output, or the ability to connect multiple monitors.

A misconception regarding high end video cards is that they are strictly used for video games. High end video cards have a much broader range of capability; for example, they play a very important role for graphic designers and 3D animators, who tend to require optimum displays as well as faster rendering.

Video cards are not used exclusively in IBM type PCs; they have been used in devices such as Commodore Amiga (connected by the slots Zorro II and Zorro III), Apple II, Apple Macintosh, Atari Mega ST/TT (attached to the MegaBus or VME interface), Spectravideo SVI-328, MSX, and in video game consoles.

Video hardware can be integrated on the mainboard, as it often happened with early computers; in this configuration it was sometimes referred to as a video controller or graphics controller.

RAM of Computer

n computer science, random access machine (RAM) is an abstract machine in the general class of register machines. The RAM is very similar to the counter machine but with the added capability of 'indirect addressing' of its registers. Like the counter machine the RAM has its instructions in the finite-state portion of the machine (the so-called Harvard architecture).

The RAM's equivalent of the Universal Turing machine -- with its program in the registers as well as its data -- is called the Random access stored program machine or RASP. It is an example of the so-called von Neumann architecture and is closest to the common notion of computer.

Together with the Turing machine and counter machine models, the RAM and RASP models are used for computational complexity analysis. Van Emde Boas (1990) calls these three plus the pointer machine "sequential machine" models, to distinguish them from "parallel random access machine" models

CPU of computer

The fundamental operation of most CPUs, regardless of the physical form they take, is to execute a sequence of stored instructions called a program. The program is represented by a series of numbers that are kept in some kind of computer memory. There are four steps that nearly all CPUs use in their operation: fetch, decode, execute, and writeback.

The first step, fetch, involves retrieving an instruction (which is represented by a number or sequence of numbers) from program memory. The location in program memory is determined by a program counter (PC), which stores a number that identifies the current position in the program. In other words, the program counter keeps track of the CPU's place in the current program. After an instruction is fetched, the PC is incremented by the length of the instruction word in terms of memory units.[3] Often the instruction to be fetched must be retrieved from relatively slow memory, causing the CPU to stall while waiting for the instruction to be returned. This issue is largely addressed in modern processors by caches and pipeline architectures (see below).

The instruction that the CPU fetches from memory is used to determine what the CPU is to do. In the decode step, the instruction is broken up into parts that have significance to other portions of the CPU. The way in which the numerical instruction value is interpreted is defined by the CPU's instruction set architecture (ISA).[4] Often, one group of numbers in the instruction, called the opcode, indicates which operation to perform. The remaining parts of the number usually provide information required for that instruction, such as operands for an addition operation. Such operands may be given as a constant value (called an immediate value), or as a place to locate a value: a register or a memory address, as determined by some addressing mode. In older designs the portions of the CPU responsible for instruction decoding were unchangeable hardware devices. However, in more abstract and complicated CPUs and ISAs, a microprogram is often used to assist in translating instructions into various configuration signals for the CPU. This microprogram is sometimes rewritable so that it can be modified to change the way the CPU decodes instructions even after it has been manufactured.

After the fetch and decode steps, the execute step is performed. During this step, various portions of the CPU are connected so they can perform the desired operation. If, for instance, an addition operation was requested, an arithmetic logic unit (ALU) will be connected to a set of inputs and a set of outputs. The inputs provide the numbers to be added, and the outputs will contain the final sum. The ALU contains the circuitry to perform simple arithmetic and logical operations on the inputs (like addition and bitwise operations). If the addition operation produces a result too large for the CPU to handle, an arithmetic overflow flag in a flags register may also be set.

The final step, writeback, simply "writes back" the results of the execute step to some form of memory. Very often the results are written to some internal CPU register for quick access by subsequent instructions. In other cases results may be written to slower, but cheaper and larger, main memory. Some types of instructions manipulate the program counter rather than directly produce result data. These are generally called "jumps" and facilitate behavior like loops, conditional program execution (through the use of a conditional jump), and functions in programs.[5] Many instructions will also change the state of digits in a "flags" register. These flags can be used to influence how a program behaves, since they often indicate the outcome of various operations. For example, one type of "compare" instruction considers two values and sets a number in the flags register according to which one is greater. This flag could then be used by a later jump instruction to determine program flow.

Memory Card Reader

A memory card reader is a device, typically having a USB interface, for accessing the data on a memory card such as a CompactFlash (CF), Secure Digital (SD) or MultiMediaCard (MMC). Most card readers also offer write capability, and together with the card, this can function as a pen drive.
A PC having a cardreader instead of floppy disk drive.

Some printers and personal computers have a built-in card reader.

A multi card reader is a device used for communication with more than one type of flash memory card. Multi card readers do not have any built-in memory capacity, but are able to accept multiple types and styles of memory cards. Multi card readers typically use a USB interface to connect with a USB-capable computer or other device, enabling users to access information stored in the memory card. The number of compatible memory cards varies from reader to reader and can include more than 20 different types. The number of different memory cards that a multi card reader can accept is expressed as x-in-1, with x being the number of memory cards accepted. Such as 35-in-1. There are three categories of card readers sorted by the type and quantity of the card slots: single card reader (e.g. 1x SD-only), multi card reader (e.g. 9-in-1) and series card reader (e.g. 4x SD only). However, there are some kinds of memory cards with USB functions that do not need the card reader, such as the Intelligent Stick memory card, which can plug directly into a USB slot

Track Ball

A trackball is a pointing device consisting of a ball held by a socket containing sensors to detect a rotation of the ball about two axes—like an upside-down mouse with an exposed protruding ball. The user rolls the ball with the thumb, fingers, or the palm of the hand to move a cursor. Large tracker balls are common on CAD workstations for easy precision. Before the advent of the touchpad, small trackballs were common on portable computers, where there may be no desk space on which to run a mouse. Some small thumbballs clip onto the side of the keyboard and have integral buttons with the same function as mouse buttons. The trackball was invented by Tom Cranston and Fred Longstaff as part of the Royal Canadian Navy's DATAR system in 1952[1], eleven years before the mouse was invented. This first trackball used a Canadian five-pin bowling ball.
The world's first trackball invented by Tom Cranston, Fred Longstaff and Kenyon Taylor working on the Royal Canadian Navy's DATAR project in 1952. It used a standard Canadian five-pin bowling ball.

When mice still used a mechanical design (with slotted 'chopper' wheels interrupting a beam of light to measure rotation), trackballs had the advantage of being in contact with the user's hand, which is generally cleaner than the desk or mousepad and doesn't drag lint into the chopper wheels. The late 1990s replacement of mouseballs by direct optical tracking put trackballs at a disadvantage and forced them to retreat into niches where their distinctive merits remained more important. Most trackballs now have direct optical tracking which follows dots on the ball.

As with modern mice, most trackballs now have an auxiliary device primarily intended for scrolling. Some have a scroll wheel like most mice, but the most common type is a “scroll ring” which is spun around the ball. Kensington's SlimBlade Trackball similarly tracks the ball itself in three dimensions for scrolling.

Currently, the trackball has become extremely hard to find. Only two major companies, Logitech and Kensington, continue to produce them, although Logitech has not released a new model in several years and has been gradually discontinuing the models it still produces. Microsoft was a major producer, but has since discontinued all of its products. The Microsoft Trackball Explorer continues to be extremely popular (it has no analogous design in production by another company), with used models selling for ~$200 on ebay.

Computer joysticks

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 (see also Centre stick vs side-stick).

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.

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 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.

Modern scanners typically use a charge-coupled device (CCD) or a Contact Image Sensor (CIS) as the image sensor, whereas older drum scanners use a photomultiplier tube as the image sensor. A rotary scanner, used for high-speed document scanning, is another type of drum scanner, using a CCD array instead of a photomultiplier. Other types of scanners are planetary scanners, which take photographs of books and documents, and 3D scanners, for producing three-dimensional models of objects.

Another category of scanner is digital camera scanners, which are based on the concept of reprographic cameras. Due to increasing resolution and new features such as anti-shake, digital cameras have become an attractive alternative to regular scanners. While still having disadvantages compared to traditional scanners (such as distortion, reflections, shadows, low contrast), digital cameras offer advantages such as speed, portability, gentle digitizing of thick documents without damaging the book spine. New scanning technologies are combining 3D scanners with digital cameras to create full-color, photo-realistic 3D models of objects.

In the biomedical research area, detection devices for DNA microarrays are called scanners as well. These scanners are high-resolution systems (up to 1 µm/ pixel), similar to microscopes. The detection is done via CCD or a photomultiplier tube (PMT).

Laser Printer

A laser beam projects an image of the page to be printed onto an electrically charged rotating drum coated with selenium. Photoconductivity removes charge from the areas exposed to light. Dry ink (toner) particles are then electrostatically picked up by the drum's charged areas. The drum then prints the image onto paper by direct contact and heat, which fuses the ink to the paper.

Laser printers have many significant advantages over other types of printers. Unlike impact printers, laser printer speed can vary widely, and depends on many factors, including the graphic intensity of the job being processed. The fastest models can print over 200 monochrome pages per minute (12,000 pages per hour). The fastest color laser printers can print over 100 pages per minute (6000 pages per hour). Very high-speed laser printers are used for mass mailings of personalized documents, such as credit card or utility bills, and are competing with lithography in some commercial applications.

The cost of this technology depends on a combination of factors, including the cost of paper, toner, and infrequent drum replacement, as well as the replacement of other consumables such as the fuser assembly and transfer assembly. Often printers with soft plastic drums can have a very high cost of ownership that does not become apparent until the drum requires replacement.

A duplexing printer (one that prints on both sides of the paper) can halve paper costs and reduce filing volumes. Formerly only available on high-end printers, duplexers are now common on mid-range office printers, though not all printers can accommodate a duplexing unit. Duplexing can also give a slower page-printing speed, because of the longer paper path.

In comparison with the laser printer, most inkjet printers and dot-matrix printers simply take an incoming stream of data and directly imprint it in a slow lurching process that may include pauses as the printer waits for more data. A laser printer is unable to work this way because such a large amount of data needs to output to the printing device in a rapid, continuous process. The printer cannot stop the mechanism precisely enough to wait until more data arrives, without creating a visible gap or misalignment of the dots on the printed page.

Instead the image data is built up and stored in a large bank of memory capable of representing every dot on the page. The requirement to store all dots in memory before printing has traditionally limited laser printers to small fixed paper sizes such as letter or A4. Most laser printers are unable to print continuous banners spanning a sheet of paper two meters long, because there is not enough memory available in the printer to store such a large image before printing begins.

Web Camera

Webcams typically include a lens, an image sensor, and some support electronics. Various lenses are available, the most common being a plastic lens that can be screwed in and out to set the camera's focus. Fixed focus lenses, which have no provision for adjustment, are also available. As a camera system's depth of field is greater for small imager formats and is greater for lenses with a large f/number (small aperture), the systems used in webcams have sufficiently large depth of field that the use of a fixed focus lens does not impact image sharpness much. Image sensors can be CMOS or CCD, the former being dominant for low-cost cameras, but CCD cameras do not necessarily outperform CMOS-based cameras in the low cost price range. Most consumer webcams are capable of providing VGA-resolution video at a frame rate of 30 frames per second. Many newer devices can produce video in multi-megapixel resolutions, and a few can run at high frame rates such as the PlayStation Eye, which can produce 320×240 video at 120 frames per second.

Support electronics are present to read the image from the sensor and transmit it to the host computer. The camera pictured to the right, for example, uses a Sonix SN9C101 to transmit its image over USB. Some cameras - such as mobile phone cameras - use a CMOS sensor with supporting electronics "on die", i.e. the sensor and the support electronics are built on a single silicon chip to save space and manufacturing costs. Most webcams feature built in microphones to make video conferencing more convenient.

The USB video device class (UVC) specification allows for interconnectivity of webcams to computers even without proprietary drivers installed. Microsoft Windows Vista, Linux[6] and Mac OS X 10.4 & 10.5 have UVC drivers built in and do not require extra drivers, although they are often installed in order to add additional features.

Light Pens

A light pen is a computer input device in the form of a light-sensitive wand used in conjunction with a computer's CRT TV set or monitor. It allows the user to point to displayed objects, or draw on the screen, in a similar way to a touch screen but with greater positional accuracy. A light pen can work with any CRT-based display, but not with LCD screens (though Toshiba and Hitachi displayed a similar idea at the "Display 2006" show in Japan[1]), projectors and other display devices.

A light pen is fairly simple to implement. The light pen works by sensing the sudden small change in brightness of a point on the screen when the electron gun refreshes that spot. By noting exactly where the scanning has reached at that moment, the X,Y position of the pen can be resolved. This is usually achieved by the light pen causing an interrupt, at which point the scan position can be read from a special register, or computed from a counter or timer. The pen position is updated on every refresh of the screen.

The light pen became moderately popular during the early 1980s. It was notable for its use in the Fairlight CMI, and the BBC Micro. Even some consumer products were given light pens, in particular Thomson's TO7 and TO7/70 computers. Because the user was required to hold his or her arm in front of the screen for long periods of time, the light pen fell out of use as a general purpose input device.

The first light pen was created around 1952 as part of the Whirlwind project at MIT.[2][3]

Since the current version of the game show Jeopardy! began in 1984, contestants have used a light pen to write down their wagers and responses for the Final Jeopardy! round.

Since light pens operate by detecting light emitted by the screen phosphors, some nonzero intensity level must be present at the coordinate position to be selected.

Dail up Modem

Dial-up connections to the Internet require no infrastructure other than the telephone network. As telephone access is widely available, dial-up remains useful to travelers. Dial-up is usually the only choice available for rural or remote areas where broadband installations are not prevalent due to low population and demand. Dial-up access may also be an alternative for users on limited budgets as it is offered for free by some ISPs, though broadband is increasingly available at lower prices in many countries due to market competition.

Dial-up requires time to establish a usable telephone connection (several seconds, depending on the location) and perform handshaking for protocol synchronization before data transfers can take place. In locales with telephone connection charges, each connection incurs an incremental cost. If calls are time-metered, the duration of the connection incurs costs.

Dial-up access is a transient connection, because either the user or the ISP terminates the connection. Internet service providers will often set a limit on connection durations to prevent hogging of access, and will disconnect the user — requiring reconnection and the costs and delays associated with it. Technically-inclined users often find a way to disable the auto-disconnect program such that they can remain connected for days. This is particularly useful for downloading ultra-large files such as videos.

A 2008 Pew Internet and American Life Project study states that only 10 percent of American adults still use dial-up Internet access. Reasons for retaining dial-up access span from lack of infrastructure to high broadband prices

Fibre optic cable

An optical fiber (or fibre) is a glass or plastic fiber that carries light along its length. Fiber optics is the overlap of applied science and engineering concerned with the design and application of optical fibers. Optical fibers are widely used in fiber-optic communications, which permits transmission over longer distances and at higher bandwidths (data rates) than other forms of communications. Fibers are used instead of metal wires because signals travel along them with less loss, and they are also immune to electromagnetic interference. Fibers are also used for illumination, and are wrapped in bundles so they can be used to carry images, thus allowing viewing in tight spaces. Specially designed fibers are used for a variety of other applications, including sensors and fiber lasers.

Light is kept in the core of the optical fiber by total internal reflection. This causes the fiber to act as a waveguide. Fibers which support many propagation paths or transverse modes are called multi-mode fibers (MMF), while those which can only support a single mode are called single-mode fibers (SMF). Multi-mode fibers generally have a larger core diameter, and are used for short-distance communication links and for applications where high power must be transmitted. Single-mode fibers are used for most communication links longer than 550 metres (1,800 ft).

Joining lengths of optical fiber is more complex than joining electrical wire or cable. The ends of the fibers must be carefully cleaved, and then spliced together either mechanically or by fusing them together with an electric arc. Special connectors are used to make removable connections.

Floppy Drive

A floppy disk is a data storage medium that is composed of a disk of thin, flexible ("floppy") magnetic storage medium encased in a square or rectangular plastic shell. Floppy disks are read and written by a floppy disk drive or FDD, the initials of which should not be confused with "fixed disk drive," which is another term for a (nonremovable type of) hard disk drive. Invented by IBM, floppy disks in 8-inch (200 mm), 5¼-inch (133⅓ mm), and 3½-inch (90 mm) formats enjoyed many years as a popular and ubiquitous form of data storage and exchange, from the mid-1970s to the late 1990s. While floppy disk drives still have some limited uses, especially with legacy industrial computer equipment,[2] they have now been largely superseded by USB flash drives, External Hard Drives, CD-ROMs, DVD-ROMs, and memory cards (such as Secure Digital)

DVD CDs

DVD, also known as "Digital Versatile Disc" or "Digital Video Disc," is an
optical disc storage media format. Its main uses are video and data storage. DVDs
are of the same dimensions as compact discs (CDs) but store more than six times
as much data.

Variations of the term DVD often describe the way data is stored on the discs:
DVD-ROM (Read Only Memory), has data that can only be read and not written, DVD-R
and DVD+R can record data only once and then function as a DVD-ROM. DVD-RW,
DVD+RW and DVD-RAM can both record and erase data multiple times. The wavelength
used by standard DVD lasers is 650 nm,[1] and thus the light has a red color.
DVD-Video and DVD-Audio discs respectively refer to properly formatted and
structured video and audio content. Other types of DVDs, including those with
video content, may be referred to as DVD-Data discs.

As next generation High Definition more advanced optical formats such as Blu-ray
Disc also use a disc identical in some aspects, the original DVD is occasionally
given the retronym SD DVD (for standard definition).[2][3] However, the
trademarked HD DVD discs have been discontinued since Blu-ray absorbed their
market share.

Computer Speakers

Computer speakers, or multimedia speakers, are external speakers, commonly
equipped with a low-power internal amplifier. The standard audio connection is a
3.5mm (1/8 inch) stereo jack plug often colour-coded lime green (following the PC
99 standard) for computer sound cards. A plug and socket for a two-wire (signal
and ground) coaxial cable that is widely used to connect analog audio and video
components. Also called a "phono connector," rows of RCA sockets are found on the
backs of stereo amplifiers and numerous A/V products. The prong is 1/8" thick by
5/16" long. A few use an RCA connector for input. There are also USB speakers
which are powered from the 5 volts at 200 milliamps provided by the USB port,
allowing about half a watt of output power.

Computer speakers range widely in quality and in price. The computer speakers
typically packaged with computer systems are small plastic boxes with mediocre
sound quality. Some of the slightly better computer speakers have equalization
features such as bass and treble controls, improving their sound quality
somewhat.
The internal amplifiers require an external power source, known as a 'wall-wart'.
More sophisticated computer speakers may have a 'subwoofer' unit, to enhance bass
output, and these units usually include the power amplifiers both for the bass
speaker, and the small 'satellite' speakers.

Some computer displays have rather basic speakers built-in.
Laptops come with integrated speakers. Unfortunately the tight restriction on
space inevitable in laptops means these speakers unavoidably produce low-quality
sound.

For some users, a lead connecting computer sound output to an existing stereo
system is practical. This normally yields much better results than small low-cost
computer speakers.

Motherboard

Most computer motherboards produced today are designed for IBM-compatible
computers, which currently account for around 90% of global PC sales[citation
needed]. A motherboard, like a backplane, provides the electrical connections by
which the other components of the system communicate, but unlike a backplane, it
also hosts the central processing unit, and other subsystems and devices.
Motherboards are also used in many other electronics devices such as mobile
phones,stop-watches,clocks,and other small electronic devices.
A typical desktop computer has its microprocessor, main memory, and other
essential components on the motherboard. Other components such as external
storage, controllers for video display and sound, and peripheral devices may be
attached to the motherboard as plug-in cards or via cables, although in modern
computers it is increasingly common to integrate some of these peripherals into
the motherboard itself.

An important component of a motherboard is the microprocessor's supporting
chipset, which provides the supporting interfaces between the CPU and the various
buses and external components. This chipset determines, to an extent, the
features and capabilities of the motherboard.
Modern motherboards include, at a minimum:

* sockets (or slots) in which one or more microprocessors are installed[3]

* slots into which the system's main memory is installed (typically in the
form of DIMM modules containing DRAM chips)

* a chipset which forms an interface between the CPU's front-side bus, main
memory, and peripheral buses

* non-volatile memory chips (usually Flash ROM in modern motherboards)
containing the system's firmware or BIOS

* a clock generator which produces the system clock signal to synchronize the
various components

* slots for expansion cards (these interface to the system via the buses
supported by the chipset)

* power connectors flickers, which receive electrical power from the computer
power supply and distribute it to the CPU, chipset, main memory, and expansion
cards.

CD-Rom

CD-ROM (pronounced /si:di:r?m/, see-dee-rom; an initialism of "compact disc read-only memory") is a pre-pressed compact disc that contains data accessible to, but not writable by, a computer. While the compact disc format was originally designed for music storage and playback, the 1985 “Yellow Book” standard developed by Sony and Philips adapted the format to hold any form of binary data.[1]

CD-ROMs are popularly used to distribute computer software, including games and multimedia applications, though any data can be stored (up to the capacity limit of a disc). Some CDs hold both computer data and audio with the latter capable of being played on a CD player, while data (such as software or digital video) is only usable on a computer (such as PC CD-ROMs). These are called enhanced CDs.

Although many people use lowercase letters in this acronym, proper presentation is in all capital letters with a hyphen between CD and ROM. It was also suggested by some, especially soon after the technology was first released, that CD-ROM was an acronym for "Compact Disc read-only-media", or that it was a more "correct" definition. This was not the intention of the original team who developed the CD-ROM, and common acceptance of the "memory" definition is now almost universal. This is probably in no small part due to the widespread use of other "ROM" acronyms such as Flash-ROMs and EEPROMs where "memory" is usually the correct term.

Networking Cables

A local area network (LAN) is a computer network covering a small physical area, like a home, office, or small group of buildings, such as a school, or an airport. Current wired LANs are most likely to be based on Ethernet technology, although new standards like ITU-T G.hn also provide a way to create a wired LAN using existing home wires (coaxial cables, phone lines and power lines)^[2].

For example, a library may have a wired or wireless LAN for users to interconnect local devices (e.g., printers and servers) and to connect to the internet. On a wired LAN, PCs in the library are typically connected by category 5 (Cat5) cable, running the IEEE 802.3 protocol through a system of interconnected devices and eventually connect to the Internet. The cables to the servers are typically on Cat 5e enhanced cable, which will support IEEE 802.3 at 1 Gbit/s. A wireless LAN may exist using a different IEEE protocol, 802.11b, 802.11g or possibly 802.11n. The staff computers (bright green in the figure) can get to the color printer, checkout records, and the academic network and the Internet. All user computers can get to the Internet and the card catalog. Each workgroup can get to its local printer. Note that the printers are not accessible from outside their workgroup

Microphones

A microphone, which was originally invented by Emile Berliner in 1877, is a
device which allows you to record voices or sounds and place them onto computers,
generally as a wav file. Microphones also can be used with other applications
such as a voice dictation program or a voice conference program.

While not all computers come with microphones, a microphone can be purchased at a
local retail store such as radio shack or any other retail store. When purchasing
a microphone, it is not always necessary to purchase a microphone capable of
recording extended frequencies as the normal human voice is only capable of going
so high or low.

While generally Microphones are a separate computer component, some manufacturers
are integrating the microphone into computers. Generally, integrated microphones
can be found on laptops and some desktop monitors. Integrated Microphones are
usually a small hole in front of the computer which when spoken into will record
your voice.

DSL Internet Switcher

The TL-SG1008D 8-port Gigabit Ethernet Switch provides you with a
high-performance, low-cost, easy-to-use, seamless and standard upgrade to improve
old network to 1000Mbps network. Increase the speed of your network server and
backbone connections, or make Gigabit to the desktop a reality. Power users in
the home, office, workgroup, or creative production environment can now move
large, bandwidth-intensive files faster. Transfer graphics, CGI, CAD, or
multimedia files and other applications that have to move large files across the
network almost instantly.

The TL-SG1005D 5-port Gigabit Ethernet Switch provides you with a
high-performance, low-cost, easy-to-use, seamless and standard upgrade to improve
old network to 1000Mbps network. Increase the speed of your network server and
backbone connections, or make Gigabit to the desktop a reality. Power users in
the home, office, workgroup, or creative production environment can now move
large, bandwidth-intensive files faster. Transfer graphics, CGI, CAD, or
multimedia files and other applications that have to move large files across the
network almost instantly.

TL-SG1005D adopts Green Ethernet technology. It can automatically power down
ports that have no link, and budget power output for different cable length. With
Green Ethernet technology, T:-SG1005D can help you save power and network cost.

Intel Microprocessors

Microprocessors made by Intel Corporation form the foundation of all PCs. Models after the 8086 are often referred to by the last three digits (for example, the 286, 386, and 486 ). Many of the microprocessors come in different varieties that run at various clock rates. The 80486 architecture, for example, supports clock rates of from 33 to 66 MHz. Because Intel discovered that it couldn't trademark its CPU numbers, it shifted to a naming scheme, starting with the Pentium processors. Intel's latest and sixth-generation chip is called the Pentium Pro. All Intel microprocessors are backward compatible, which means that they can run programs written for a less powerful processor.
The 80386, for example, can run programs written for the 8086, 8088, and 80286. The 80386 and later models, however, offer special programming features not available on previous models. Software written specifically for these processors, therefore, may not run on older microprocessors. The common architecture behind all Intel microprocessors is known as the x86 architecture. Until the late 80s, Intel was essentially the only producer of PC microprocessors.
Increasingly, however, Intel is facing competition from other manufacturers who produce "Intel-compatible " chips. These chips support the Intel instruction set and are often less expensive than Intel chips. In some cases, they also offer better performance. Two of the leading manufacturers of Intel-compatible chips are Cyrix and AMD.

USB Flash drives

A USB flash drive consists of a NAND-type flash memory data storage
device integrated with a USB (universal serial bus) interface. USB flash
drives are typically removable and rewritable, much smaller than a floppy
disk (1 to 4 inches or 2.5 to 10 cm), and most USB flash drives weigh
less than an ounce (28g).[1] Storage capacities typically range from 64
MB to 128 GB[2] with steady improvements in size and price per gigabyte.
Some allow 1 million write or erase cycles[3][4] and have 10-year data
retention,[5] connected by USB 1.1 or USB 2.0.

USB flash drives offer potential advantages over other portable storage
devices, particularly the floppy disk. They have a more compact shape,
operate faster, hold much more data, have a more durable design, and
operate more reliably due to their lack of moving parts. Additionally, it
has become increasingly common for computers to be sold without floppy
disk drives. USB ports, on the other hand, appear on almost every
current[update] mainstream PC and laptop. These types of drives use the
USB mass storage standard, supported natively by modern operating systems
such as Windows, Mac OS X, Linux, and other Unix-like systems. USB drives
with USB 2.0 support can also operate faster than an optical disc drive,
while storing a larger amount of data in a much smaller space.

Wire less Mouse

No Tail Required:

With its secure, reliable Bluetooth technology, the wireless Mighty Mouse goes wherever you
do. Pair it with any Bluetooth-enabled Mac and wireless keyboard to work untethered and
uncluttered at your desk, or take your show on the road. The wireless Mighty Mouse lightens
your load on the go by operating with either one or two AA batteries. That’ll save you
lugging a bulky dock around.

The wireless Mighty Mouse’s tracking engine is based on powerful laser technology that
delivers 20 times the performance of standard optical tracking, giving you more accuracy and
responsiveness on more surfaces. It works just as well on a table at your favorite coffee
spot as it does on your office desk. Which means you can leave the mouse pad at home.

Apple keyboard "Flat"

Could it be that a flat, standard keyboard using rubber membranes could displace the mechanical key switch-using Datadesk Smartboard I had come to know and love? That was the question I set out to answer when I purchased the Apple Keyboard (wired version) a month and a half after its debut in August of last year. I’ve been using Apple’s latest keyboard since mid-September, and I haven’t looked back.

Though it has been termed Apple’s “Aluminum Keyboard” for the purpose of identification, the only aluminum part of it is the slender top surface. The even slimmer bottom surface is made of white plastic, like the keys atop. In a nod to the color of the aluminum, the print on the keys isn’t black, as one might expect, but a grey.

The keys themselves are, of course, inspired by the keyboards of the MacBook line. My only experiences with such a keyboard prior to the purchase of this one, were the few times I’d tapped out lines in TextEdit while on a MacBook in an Apple Store. Not long enough to make a truly informed decision, but at least long enough to know I didn’t totally hate it. As it turned out, not only do I not hate the keys on the Aluminum Keyboard, I love them. So much so, that I’m hoping Apple brings this keyboard style to the next MacBook Pro refresh.

Speaking of the keys, the function keys on the Aluminum Keyboard sport a lot more functions than did those of its predecessors. With the Keyboard Software Update installed, not only do they control the brightness and volume levels of your system, but they can also launch Dashboard and Exposé, and control iTunes. For me, enabling these features meant finding a new capture key for EagleFiler, which by default is F1. Apple has left F5 and F6 “blank,” so F5 was the winner.

Maxtor 100 GB Hard disk

Maxtor was the first company to announce a 100GB IDE/ATA hard drive in spring 2001. The DiamondMax 536DX 100GB drive features an ATA/100 interface (backward compatible with most older IDE controllers),
2MB of cache and 5400 RPM spindle speed. (Western Digital recently announced a 100GB, 7200 RPM drive for the same price, but it was not available at retail as I'm writing this.) Although originally thought to have a 40GB/platter density,
the 100GB Maxtor actually is 33.3GB per platter. Current list price of the 100GB Maxtor drive is $299.95. OEM versions (drive only/no retail package) may be less.
This drive was purchased for a G4 Cube, which can have only one internal drive - so capacity and low-noise were major factors in choosing this model.
(BTW - Who would have thought a year or so ago you could have an 8-inch cube sized computer with 100GB of storage and 1GB of RAM.

15" Slim Bezel TFT LCD Monitor

Flatron TFT-LCD monitors represent the cutting edge in technology and style. As one of the largest manufacturers of monitors, LG brings Flatron TFT-LCD to the market with ultimate efficiencies in design, performance, reliability and value. Flatron TFT-LCD monitors provide bright, sharp and vivid images ensuring stunning displays. The slim design provides a better working and living environment with extra space and cleanliness. The wide viewing technology provides wide viewing angles in every direction to prevent colors and images form deviation. Auto adjustment function automatically sets image position, phase and pitch. A unique feature of the LG's LCD monitor is the ability to mount the display on the wall and arm. Mounting slots on the back allow the LG's LCD monitor to be hung vertically or horizontally - just like a picture. A built-in power brick provides users with reduced desktop clutter from crisscrossing cables, creating extra space and cleanliness. The monitor's transparent OSD background enables users not to be interfered with their work.