Archive for March 8, 2008

ROUTER

{ March 8, 2008 @ 2:51 pm } · { NETWORKING }
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There are two types of Router

  • Cable Router
If you have high speed cable Internet in your house, chances are that you also have a cable router. A cable modem plugs in to the cable coming from the wall, which may also provide you with cable television. The cable router then plugs into your cable modem, and transfers the signal to your home computers.A router is a device that acts as connection between two different networks. In this case, the cable company has one network, which includes your Internet connection. The other network is your home computer or computers. The cable router allows these two networks to connect with each other and share information.The information sent between your home computer and the cable Internet service provider, or ISP, can include many different types of data. The cable router, as the name suggests, routes this data to where it needs to go. For example, if you have two computers on your home network, and you use one of them to access the shared picture files on the second computer, the cable router gets the information request from the first computer, and routes it to the second computer. If the second computer is trying to view a web page, the cable router takes this request and routes it to the cable Internet service provider. When the ISP sends the web page information back, the cable router sends it to the second computer.When you decide to purchase a cable router, there are several things to consider. Some cable routers come with built in firewalls. These firewalls protect your home computers from hackers and help to secure your network. If you have software firewalls on your home computers, you may not need a hardware firewall on your cable router, but the extra security may be worth the extra price.

Another consideration when shopping for a cable router is whether you want a wireless network, or plan to use network cables. The most common type of network cable is CAT5 (pronounced cat five). A wired cable router is suitable when all your computers are close to the cable router. The wires can lose the signal if the computers are too far away, and running long cables all over a house or office can be messy. Keep in mind that you will want enough ports on the router to supply all your computers with a connection.

A wireless cable router might be a good choice if there are multiple computers, or if the computers are spread out in different rooms or on different floors. The wireless cable router’s signal will still suffer from long range, but you won’t have to run wires across the floor or drill holes between rooms. When you get your cable Internet service installed, you can ask your installer or the representative from the cable company if they recommend any particular cable routers to go with their products. A knowledgeable sales associate in your local computer store will be able to help you find the right cable modem for your network, and help you with any additional cables or other hardware you might need.

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  • MIMO Router

MIMO routers are the next big thing in wireless networking. They handily extend the range of Wi-Fi network base stations. As such, they are sure to be a hit with the Wi-Fi crowd for years to come.

MIMO routers build on the MIMO technology, which stands for Multiple Input, Multiple Output. This relatively new set of technology protocols reinvents the way that signals are transmitted and received. MIMO routers send out multiple data streams at the same time and then use multiple antennas to sift through the signals for the requisite pattern. All this is done while maintaining a fast connection and, hence, a fast data stream.

Actually, MIMO is a new verse of an old song. The technology has been pursued for years in the digital radio industry with varying success. Nowadays, it seems to be the standard, provided that both the transmitting and the receiving party have multiple antennas with which to send or receive the multiple streams of data.

The same is true of MIMO routers, which replace standard routers in the technological advancement universe. The earliest models of routers have one antenna, with which they receive one data stream. Even if the sending party were sending multiple streams of data, the traditional router, with its one antenna, would not be able to receive those multiple streams of data. Enter the MIMO router. Multiple antennas mean multiple streams of data, and that means better performance.

MIMO routers attach to any home or office network just as easily as other types of routers. MIMO routers allow high-profile encryption pathways as well, so you can rest assured that those multiple data streams aren’t being infiltrated by hackers. This encryption is delivered without loss of signal strength or speed.

Speaking of speed, MIMO routers transmit data at speeds faster than standard routers today. The protocols with which MIMO routers are equipped provide for protection against data scattering, which is both a hazard to transmission and a guaranteed slowdown in transmission speed. Buying a MIMO router, therefore, to replace your existing router is an upgrade in both range and speed. MIMO routers are engineered to be compatible with the newest standard of wireless, 802.11n, but the same MIMO routers are also backward-compatible with previous wireless standards. This is one of those products that you can buy and actually keep around for awhile.

NETWORKING SWITCH

{ March 8, 2008 @ 2:43 pm } · { NETWORKING }
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A networking switch is the central device in a wired or wireless LAN (local area network). It receives signals from each computer on the network via Ethernet cables in a wired network or radio waves in a wireless LAN. In both cases, the networking switch directs traffic across the LAN, enabling the computers to talk to each other and share resources.

All computers included in the LAN must contain a network interface card (NIC). The card assigns a unique address to the machine in which it is installed. This address is called a MAC (Medium Access Control). A wired NIC accommodates an Ethernet cable, which runs to a port on the back of the networking switch. If the NIC is wireless, the card will feature a small antenna instead of an Ethernet port. The antenna transmits signals to the wireless networking switch, which also bears an antenna rather than ports. Whether wireless or wired, the networking switch acts as a relay, reading traffic packets as they arrive from the various machines and directing the packets to the proper MAC address.

A networking switch runs in full-duplex mode, meaning a machine on the LAN can receive and transmit data simultaneously. This is much faster than a networking hub, an alternate device that serves the same purpose as a switch but operates in half-duplex mode, allowing each machine or node either to send or receive at any given time. Another key difference between a networking switch and a hub is that the switch sends traffic discriminately, using addresses to direct traffic packets exactly where they are supposed to go. Conversely, a networking hub broadcasts all traffic on the network to all nodes, relying on filters within each machine to discard packets not addressed to it. This makes networks that use a hub particularly vulnerable to “packet sniffers” or eavesdropping.

For the above reasons, a networking switch is considered superior to a networking hub. However, a networking switch is also not foolproof. It can be “tricked” into accommodating packet sniffers, but the methods used to trick the switch will leave telltale traffic signatures, unlike the passive methods that can be used on a hub. Anti-sniffing software can be installed on a switched network to detect packet sniffers.

Network switches are inexpensive devices that increase in price with the number of ports featured. A basic Ethernet networking switch might come with five ports at a cost of about US$30. For those with cable modem or DSL service, a broadband router with a built-in switch and firewall can be used in lieu of a stand-alone networking switch.

NETWORKING SWITCH

{ March 8, 2008 @ 2:42 pm } · { NETWORKING }
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A networking switch is the central device in a wired or wireless LAN (local area network). It receives signals from each computer on the network via Ethernet cables in a wired network or radio waves in a wireless LAN. In both cases, the networking switch directs traffic across the LAN, enabling the computers to talk to each other and share resources.

All computers included in the LAN must contain a network interface card (NIC). The card assigns a unique address to the machine in which it is installed. This address is called a MAC (Medium Access Control). A wired NIC accommodates an Ethernet cable, which runs to a port on the back of the networking switch. If the NIC is wireless, the card will feature a small antenna instead of an Ethernet port. The antenna transmits signals to the wireless networking switch, which also bears an antenna rather than ports. Whether wireless or wired, the networking switch acts as a relay, reading traffic packets as they arrive from the various machines and directing the packets to the proper MAC address.

A networking switch runs in full-duplex mode, meaning a machine on the LAN can receive and transmit data simultaneously. This is much faster than a networking hub, an alternate device that serves the same purpose as a switch but operates in half-duplex mode, allowing each machine or node either to send or receive at any given time. Another key difference between a networking switch and a hub is that the switch sends traffic discriminately, using addresses to direct traffic packets exactly where they are supposed to go. Conversely, a networking hub broadcasts all traffic on the network to all nodes, relying on filters within each machine to discard packets not addressed to it. This makes networks that use a hub particularly vulnerable to “packet sniffers” or eavesdropping.

For the above reasons, a networking switch is considered superior to a networking hub. However, a networking switch is also not foolproof. It can be “tricked” into accommodating packet sniffers, but the methods used to trick the switch will leave telltale traffic signatures, unlike the passive methods that can be used on a hub. Anti-sniffing software can be installed on a switched network to detect packet sniffers.

Network switches are inexpensive devices that increase in price with the number of ports featured. A basic Ethernet networking switch might come with five ports at a cost of about US$30. For those with cable modem or DSL service, a broadband router with a built-in switch and firewall can be used in lieu of a stand-alone networking switch.

TCP/IP

{ March 8, 2008 @ 2:11 pm } · { NETWORKING }
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Connection to the Internet these days has become so easy and user-friendly that we tend to forget the technical aspects of things like page loads and file downloads. Such operations still take place, even though the average user doesn’t give them a second thought.

One such overlooked set of operations is TCP/IP. This often used but little understood set of operations stands for Transmission Control Protocol/Internet Protocol. TCP/IP is the combination of the two and describes the set of protocols that allows hosts to connect to the Internet. In actuality, TCP/IP is a combination of more than those two protocols, but the TCP and IP parts of TCP/IP are the main ones and the only ones to become part of the acronym that describes the operations involved.

TCP/IP doesn’t just happen. It is an active process; a set of constant communications between private computers and Internet servers. When a computer attempts to log on to the Internet, that computer’s TCP/IP operations send a series of signals to Internet servers looking for a connection. In nearly all cases, access is successful. Some exceptions would keep access from being granted, but these exceptions are rare.

The two layers of TCP/IP are defined by the separate spelled-out versions. Transmission Control Protocol is the top layer; the one that converts messages or files into data packets that are transmitted over the network connection to the destination computer and then reassembled into messages or files that can be read by the destination user. The lower layer of TCP/IP, Internet Protocol, provides the transmitting operation, configuring the connection’s address so that the information gets to the right place. IP could function without TCP, although it would be idle, but the reverse is not possible.

Despite the very evident presence of the word Internet in the spelled-out version of TCP/IP, the set of protocols can be used for internal use as well. Company intranets utilize TCP/IP protocols in order to set up a network within the company’s computer framework. No outside connection develops, but connections are made between the company’s servers and/or mainframes and individual computers. This sort of connectivity mimics the connection functionality of TCP/IP as used for Internet connections

LAN

{ March 8, 2008 @ 2:09 pm } · { NETWORKING }
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A local area network (LAN) consists of two or more computers connected together in a building or home using software and hardware. A LAN is contrasted to a wide area network (WAN) such as the Internet, which covers a large geographic area. In a LAN, there is a main computer or server, and remote computers called clients. By creating a LAN in the home or office, computers on the LAN can share files, resources, and if desired, an Internet connection.

A LAN can be one of two types: wired or wireless. A wired LAN requires Ethernet cable to physically connect all computers on the network to a main device called a switch. A wireless LAN uses radio waves to communicate, eliminating the need for wires. Therefore, the hardware used in a LAN should all be of either the wireless or wired type.

A LAN is fairly easy to setup. All Microsoft operating systems since Windows 98 Special Edition (SE) have included built-in networking software. In terms of hardware, each computer requires a network interface card (NIC). A switch is also required. This is a device that resembles an external modem and directs information on the network. If the LAN will be talking to another network, like the Internet, a router is also required. Luckily, one can purchase an external DSL modem with a built-in switch and router, in wireless or wired configurations.

Desktop computers typically use internal NICs that slip into an available slot on the motherboard, while a laptop might use a portable computer (PC) NIC. This type of NIC resembles a thick credit card that can be inserted into the PC card slot on the laptop.

If the LAN is to be hard-wired, each NIC must have an Ethernet port for connecting an Ethernet cable. In a wireless LAN, each NIC might feature a small radio wave antenna. The server is hard-wired to the DSL modem, switch or router, while the clients can communicate wirelessly, if desired. If there is to be no connection to the Internet or any other LAN or WAN, a switch alone will be fine.

Once the LAN has been set up, an administrator can designate which files and programs can be shared on the LAN. Some areas of the server may be kept behind a firewall to prevent access. All traffic on the LAN, including email, Internet surfing and other activities, can be monitored by the administrator using various tools.

The advantages of a LAN in the office are manifold. By having a central printer, for example, a business can avoid buying individual printers for each workstation. Workflow is enhanced while being easier than ever to control and administer. Flexibility and creativity can also improve. A LAN is a win-win situation for management and employees alike.

A LAN at home is extremely convenient. Share programs, images, music and digital projects, and enjoy gaming. Share a high-end color printer, scanner or other equipment. If concerned about your children’s Internet use, a LAN is one way to supervise online activity.

A hard-wired LAN is more trouble to install, as it requires running a physical Ethernet cable from each client to the DSL, switch or router. However, a wired LAN is reliable and secure. A wireless LAN is easier to install and less expensive, but requires a few more steps in the software setup to ensure it is secure. It may also be slower than a wired LAN, but this depends on the wireless standard used, as newer standards effectively compete with Ethernet speeds.

WIFI

{ March 8, 2008 @ 2:07 pm } · { NETWORKING }
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Wi-Fi, which stands for wireless fidelity, in a play on the older term Hi-Fi, is a wireless networking technology used across the globe. Wi-Fi refers to any system that uses the 802.11 standard, which was developed by the Institute of Electrical and Electronics Engineers (IEEE) and released in 1997. The term Wi-Fi, which is alternatively spelled WiFi, Wi-fi, Wifi, or wifi, was pushed by the Wi-Fi Alliance, a trade group that pioneered commercialization of the technology.

In a Wi-Fi network, computers with wifi network cards connect wirelessly to a wireless router. The router is connected to the Internet by means of a modem, typically a cable or DSL modem. Any user within 200 feet or so (about 61 meters) of the access point can then connect to the Internet, though for good transfer rates, distances of 100 feet (30.5 meters) or less are more common. Retailers also sell wireless signal boosters that extend the range of a wireless network.

Wifi networks can either be “open”, such that anyone can use them, or “closed”, in which case a password is needed. An area blanketed in wireless access is often called a wireless hotspot. There are efforts underway to turn entire cities, such as San Francisco, Portland, and Philadelphia, into big wireless hotspots. Many of these plans will offer free, ad-supported service or ad-free service for a small fee. San Francisco recently chose Google to supply it with a wireless network.

Wifi technology uses radio for communication, typically operating at a frequency of 2.4GHz. Electronics that are “WiFi Certified” are guaranteed to interoperate with each other regardless of brand. Wifi is technology designed to cater to the lightweight computing systems of the future, which are mobile and designed to consume minimal power. PDAs, laptops, and various accessories are designed to be wifi-compatible. There are even phones under development that would switch seamlessly from cellular networks to wifi networks without dropping a call.

New wifi technologies will extend range from 300 feet (91.5 meters) to 600 feet (183 meters) and beyond, while boosting data transfer rates. Most new laptops nowadays come equipped with internal wireless networking cards.

WEBCAM

{ March 8, 2008 @ 2:04 pm } · { WORKING AND FUNCTIONALITY }
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A webcam, or web camera, is the loosely used term for any camera that generates images that can be accessed by and displayed on the world wide web through a server. A webcam is essentially just a camera that is connected to a computer, either directly or wirelessly, and gathers a series of images for remote display elsewhere. Webcam technology is widely used by all sorts of people for all sorts of different reasons.

In 1991, the first webcam was up and running at Cambridge University’s Computer Science Department, but since then, webcams have crept into homes, businesses, public streets and buildings. Webcams are often used for personal use in the home by parents who want to give distant relatives visual access to their children or want to monitor what goes on in the home while they are at work. People might also use webcams in the home to keep an eye on things while they are out of town or even just to see what their pets do all day. The uses of a webcam are limitless. Businesses often use webcams for video conferencing, and webcam technology is used by numerous other entities to give the public access to a variety of information, from weather and traffic to the feeding habits of the most recently acquired zoo animal. Some schools and day care facilities use a webcam to allow parents to see what their children do at school.

The webcam basically works by capturing a series of digital images that are transferred by the computer to a server and then displayed to the hosting page. There are even sites that allow users to upload and store their webcam images for free, which many individuals choose for personal use. Webcams vary in their capabilities and features, and the variances are reflected in price. Some webcams capture a still image only once every 30 seconds, while others provide streaming video by capturing 30 images per second. A webcam can be purchased at any computer store and most major electronics retailers, as well as online. A knowledgeable sales associate should be able to help any consumer choose the right webcam.

SATA HARD DISK

{ March 8, 2008 @ 1:58 pm } · { WORKING AND FUNCTIONALITY }
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External Serial Advanced Technology Attachment or eSATA is an external interface for SATA technologies. It competes with FireWire 400 and universal serial bus (USB) 2.0 to provide fast data transfer speeds for external storage devices.

SATA replaced ATA legacy technology as the next generation internal bus interface for hard drives. The SATA interface is more streamlined than ATA and provides serial architecture for greater speed than the older parallel technology. SATA cables are narrow and can be up to three feet (1 meter) in length, whereas parallel cables are much wider and limited to a length of 18 inches (45.7 cm). With eSATA, the speed of SATA expands to encompass exterior storage solutions.

While eSATA reaches transfer rates triple those of USB 2.0 and FireWire 400, it does have one drawback. eSATA requires its own power connector, unlike the aforementioned interfaces. However, it is an excellent choice for external disk storage. Unlike USB and FireWire interfaces, eSATA does not have to translate data between the interface and the computer. This enhances data transfer speeds, while saving computer processor resources and eliminating the need for an extra off-load chip.

For desktop motherboards that don’t have an eSATA connector, a bus card can provide an eSATA interface. Notebooks can use a peripheral component interconnect (PCI) card. eSATA enables use of fast SATA drives for external disk arrays, not only expanding valuable storage real estate, but also enabling truly fast portable storage. eSATA’s hot-swappable feature makes taking disks from work to home, or from one computer to another, a snap. Administrators, IT techs, advertising and marketing executives, and even gamers will find this beneficial.

SATA has differing standards, with older hardware supporting the original standard exclusively. With each new SATA iteration, speed increases. Original SATA, or SATA/150, has a data transfer speed of 150 megabytes per second (MB/s). SATA II or SATA/3Gbs doubled the speed to 300 MB/s or 3 gigabits per second. This is also sometimes referred to as SATA/300. Some sources report SATA/600 will be available by 2007.

When purchasing an eSATA controller or bus card, be sure it supports the SATA standard required by your SATA hard drive(s). Hardware that supports newer standards is usually backwards compatible with older devices, but the reverse does not hold. An eSATA controller made for SATA/150, for example, will not be able to support the faster transfer speeds of a SATA/300 hard drive.

TFT SCREEN

{ March 8, 2008 @ 1:50 pm } · { WORKING AND FUNCTIONALITY }
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A TFT monitor uses thin-film transistor technology for the ultimate LCD display. LCD monitors, also called flat panel displays, are replacing the old style cathode ray tubes (CRTs) as the displays of choice. Nearly all LCD monitors today use TFT technology.

The benefit of a TFT monitor is a separate, tiny transistor for each pixel on the display. Because each transistor is so small, the amount of charge needed to control it is also small. This allows for very fast re-drawing of the display, as the image is re-painted or refreshed several times per second.

Prior to TFT, passive matrix LCD displays could not keep up with fast moving images. A mouse dragged across the screen, for example, from point A to point B, would disappear between the two points. A TFT monitor can track the mouse, resulting in a display that can be used for video, gaming and all forms of multimedia.

A typical 17-inch TFT monitor has about 1.3 million pixels and 1.3 million transistors. That leaves a significant chance for a malfunctioning transistor or two on the panel. Upon delivery, a TFT monitor can have “dead pixels” for this reason. A dead pixel is a pixel whose transistor has failed, thereby creating no display image. On a solid black background, dead pixels will stand out as tiny dots of red, white or blue. Most manufacturers will not replace a TFT monitor that has less than 11 dead pixels. Often, a TFT monitor won’t have any dead pixels —- always the hope for any buyer, though dead pixels are not noticeable unless located in a critical position on the screen.

There are only a handful of TFT factories that turn out panels for all brands of TFT monitors. Since there is a given failure rate — considering how many transistors are on each panel — only so many of the displays come out bearing no dead pixels, while a certain percentage bear an acceptable number of dead pixels and other panels are unusable. The panels that bear some dead pixels are often sold to be used in discount models. If looking for a TFT monitor, it is a good idea to read feedback provided by buyers at popular online retail sites. By scanning the reviews for several brands, it is easy to get a feel for which models have consistently good panels that rarely bear dead pixels.

A TFT monitor delivers crisp text, vibrant color and an improved response time for multimedia applications. If interested in gaming, video editing or other multimedia applications, look for a TFT monitor with a response rate of 16ms or less.

HOW DOES COMPUTER WORKS? (Submitted by Ankita)

{ March 8, 2008 @ 11:13 am } · { PERSONAL COMPUTERS }
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COMPUTER 

A computer is a machine that manipulates data according to a list of instructions.

WORKING A general purpose computer has four main sections: the arithmetic and logic unit (ALU), the control unit, the memory, and the input and output devices (collectively termed I/O). These parts are interconnected by busses, often made of groups of wires.

The control unit, ALU, registers, and basic I/O (and often other hardware closely linked with these) are collectively known as a central processing unit (CPU). Early CPUs were composed of many separate components but since the mid-1970s CPUs have typically been constructed on a single integrated circuit called a microprocessor

.1.  CONTROL  UNIT.The control unit (often called a control system or central controller) directs the various components of a computer. It reads and interprets (decodes) instructions in the program one by one. The control system decodes each instruction and turns it into a series of control signals that operate the other parts of the computer.

  2. Arithmetic/logic unit (ALU)The ALU is capable of performing two classes of operations: arithmetic and logic.The set of arithmetic operations that a particular ALU supports may be limited to adding and subtracting or might include multiplying or dividing, trigonometry functions (sine, cosine, etc) and square roots. Some can only operate on whole numbers (integers) whilst others use floating point to represent real numbers—albeit with limited precision.Superscalar computers contain multiple ALUs so that they can process several instructions at the same time.

3.MEMORY           memory.jpg                         A computer’s memory can be viewed as a list of cells into which numbers can be placed or read. Each cell has a numbered “address” and can store a single number In almost all modern computers, each memory cell is set up to store binary numbers in groups of eight bits (called a byte).                              

The CPU contains a special set of memory cells called registers that can be read and written to much more rapidly than the main memory area. There are typically between two and one hundred registers depending on the type of CPU. Registers are used for the most frequently needed data items to avoid having to access main memory every time data is needed. Computer main memory comes in two principal varieties: random access memory or RAM and read-only memory or ROM. RAM can be read and written to anytime the CPU commands it, but ROM is pre-loaded with data and software that never changes, so the CPU can only read from it. ROM is typically used to store the computer’s initial start-up instructions. In general, the contents of RAM is erased when the power to the computer is turned off while ROM retains its data indefinitely.

4.MULTIPROCESSING

multitasking.jpgSome computers may divide their work between one or more separate CPUs, creating a multiprocessing configuration. Traditionally, this technique was utilized only in large and powerful computers such as supercomputers, mainframe computers and servers. However, multiprocessor and multi-core (multiple CPUs on a single integrated circuit) personal and laptop computers have become widely available and are beginning to see increased usage in lower-end markets as a result.

 5. Networking and the Internetnetwork.jpgIn the 1970s, computer engineers at research institutions throughout the United States began to link their computers together using telecommunications technology. This effort was funded by ARPA (now DARPA), and the computer network that it produced was called the ARPANET.

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