The history of computer development is often referred to in reference to the different generations of computing devices. Each generation of computer is characterized by a major technological development that fundamentally changed the way computers operate, resulting in increasingly smaller, cheaper, more powerful and more efficient and reliable devices. Read about each generation and the developments that led to the current devices that we use today. Read more...

64-bit therefore refers to a processor with registers that store 64-bit numbers. A generalization would be to suggest that 64-bit architecture would double the amount of data a CPU can process per clock cycle. Users would note a performance increase because a 64-bit CPU can handle more memory and larger files. One of the most attractive features of 64-bit processors is the amount of memory the system can support. 64-bit architecture will allow systems to address up to 1 terabyte (1000GB) of memory. In today's 32-bit desktop systems, you can have up to 4GB of RAM (provided your motherboard that can handle that much RAM) which is split between the applications and the operating system (OS). Read more...

It is becoming increasingly easy to create PDF files as (from a user's stand-point) the process is almost as simple as printing. Essentially, anything that can be done with a sheet of paper can be done with a PDF. PDF technology is being used more frequently to produce offset printed documents (provided the designer properly embeds fonts and images). Read more...

Open source usually refers to a program in which the source code is available to the general public for use and/or modification from its original design free of charge. Open source code is typically created as a collaborative effort in which programmers improve upon the code and share the changes within the community.
The rationale for this movement is that a larger group of programmers not concerned with proprietary ownership or financial gain will produce a more usefuland bug-free product for everyone to use. The concept relies on peer review to find and eliminate bugs in the program code, a process that commercially developed and packaged programs do not employ.
The basics behind the Open Source Initiative is that when programmers can read, redistribute and modify the source code for a piece of software, the software evolves. Open source sprouted in the technological community as a response to proprietary software owned by corporations. Read more...

A fingerprint is made up of a pattern of ridges and furrows as well as characteristics that occur at Minutiae points (ridge bifurcation or a ridge ending). Fingerprint scanning essentially provides an identification of a person based on the acquisition and recognition of those unique patterns and ridges in a fingerprint. Read more...

Surround Sound is the term commonly used to describe a system in which the sound output appears to surround the listener — that is, the technology gives the impression that sounds are coming from all possible directions. Surround sound is a way to provide a more realistic and engaging experience. Sitting in front of your standard television or playing a computer game with basic stereo speakers plugged in will provide you with sound. You hear the music, voices and other sounds coming to you from straight ahead. Using a surround sound system, however, you'll hear variances in the sound and and it will be presented to you from different directions. For example, the car driving off screen sounds like it is coming from the left. While playing a 3D shooter game, the rocket gun blasts sound as if they are being shot from overhead or grenades sound like they are exploding at ground level. Read more...

While the words CPU and microprocessor are used interchangeably, in the world of personal computers (PC), a microprocessor is actually a silicon chip that contains a CPU. At the heart of all personal computers sits a microprocessor that controls the logic of almost all digital devices, from clock radios to fuel-injection systems for automobiles. The three basic characteristics that differentiate microprocessors are the following:

Whenever the casing of a computer is opened and its internal workings are exposed (to change a hard drive or add memory chips, for example), there is a danger of damaging the computer with the buildup of static electricity that is held by the human body. The internal workings of a computer, and especially the hard drive, are extremely susceptible to static electricity, which can cause considerable damage to the hard drive if it is zapped with even a small amount. Microchip damage can occur if it is exposed to static electricity as low as 10 volts, and humans are not able to perceive static electricity until it has reached about 1,500 volts. (Walking across a rug can produce a static electricity voltage of up to 12,000 volts, but static voltage is not life threatening.) So it is possible to damage a hard drive with static electricity that is not even felt by the person because it is at such a low voltage. Also, computers become increasingly susceptible to static electricity damage as more and more circuitry is built into them. Read more...

Virtual tape is a concept that has been in the data center for many years. Originally introduced for IBM mainframes, it is now exploding in the open systems arena. VTLs are logically just like physical tape libraries: They logically appear and operate as physical tape devices including virtual tape drives, data cartridges, tape slots, barcode labels and robotic arms. Read more...

The appeal of USB is that it is supported at the operating system level, and compared to alternative ports such as parallel or serial ports, USB is very user-friendly. When USB first started appearing in the marketplace, it was (and still is) referred to as a plug-and-play port because of its ease of use. Consumers without a lot of technical or hardware knowledge were able to easily connect USB devices to their computer. You no longer needed to turn the computer off to install the devices either. You simply plug them in and go. USB devices can also be used across multiple platforms. USB works on Windows and Mac, plus can be used with other operating systems, such as Linux, for example, with a reliable degree of success. Read more...

A network is a group of two or more computers that intelligently share hardware or software devices with each other. A network can be as small and simple as two computers that share the printer and CD-ROM drive attached to one of them or as large as the world’s largest network: the Internet. Read more...

Several types of networks exist, from small, two-station arrangements to networks that interconnect offices in many cities:

Unless the computers that are connected know they are connected and agree on a common means of communication and what resources are to be shared, they can’t work together. Networking software is just as important as networking hardware because it establishes the logical connections that make the physical connections work.

At a minimum, each network requires the following:

On a client/server network, every computer has a distinct role, that of either a client or a server. A server is designed to share its resources among the client computers on the network. Typically, servers are located in secured areas, such as locked closets or data centers, because they hold an organization’s most valuable data and do not have to be accessed by operators on a continuous basis. The rest of the computers on the network function as clients. Read more...

Peer-to-peer networks are more common in small offices or within a single department of a larger organization. The advantage of a peer-to-peer network is that you don’t have to dedicate a computer to function as a file server. Instead, every computer can share its resources with any other. The potential disadvantages to a peer-to-peer network are that typically less security and less control exist because users normally administer their own systems, whereas client/server networks have the advantage of centralized administration. Read more...

Every computer that communicates over the Internet is assigned an IP address that uniquely identifies the device and distinguishes it from other computers on the Internet. An IP address consists of 32 bits, often shown as 4 octets of numbers from 0-255 represented in decimal form instead of binary form. For example, the IP address. Read more...

The OSI, or Open System Interconnection, model defines a networking framework for implementing protocols in seven layers. Control is passed from one layer to the next, starting at the application layer in one station, proceeding to the bottom layer, over the channel to the next station and back up the hierarchy. OSI Model

A TCP/IP service protocol that offers dynamic leased configuration of host IP addresses and distributes other configuration parameters to eligible network clients. DHCP provides safe, reliable, and simple TCP/IP network configuration, prevents address conflicts, and helps conserve the use of client IP addresses on the network. DHCP uses a client/server model where the DHCP server maintains centralized management of IP addresses that are used on the network. DHCP-supporting clients can then request and obtain lease of an IP address from a DHCP server as part of their network boot process.

For example, snail mail is connectionless, because you can send a letter to someone without them doing anything and they will receive the letter. On the other hand, the telephone system is connection-oriented, because the other party is required to pick up the phone before communication can be established. The OSI Network Layer protocol can be either connection-oriented, or connectionless. The TCP/IP Internet Layer (equivalent to OSI's Network Layer) supports only the connectionless Internet Protocol (IP).

Everybody in the network needs to have a unique address which determines who they are. This address will normally be hierarchical, so you can be "Fred Murphy" to Dubliners, or "Fred Murphy, Dublin" to people in Ireland, or "Fred Murphy, Dublin, Ireland" to people anywhere in the world. On the internet, these addresses are known as IP Numbers.

This is of particular interest to mobile applications, where a user may rapidly move from place to place, and it must be arranged that his messages follow him. Version 4 of the Internet Protocol (IPv4) doesn't really allow for this, though it has been hacked somewhat since its inception. Fortunately, the forthcoming IPv6 has a much better designed solution, which should make this type of applications much smoother.

Broadband wireless will revolutionize people's lives by enabling a high speed connection directly to the key people and information that customers want, whenever they want it. Wireless technologies such as 3G, Wi-Fi, and WiMAX will coexist, working synergistically together to meet unique customer needs.

Wireless Metropolitan Area Networks (WMANs) cover a much greater distance than WLANs, connecting buildings to one another over a broader geographic area. The emerging WiMAX technology (IEEE* 802.16 2004 specification today and the proposed IEEE* 802.16e specification in the near future) will further enable mobility and reduce reliance on wired connections.

Wireless Local Area Networks (WLANs) have broader range than WPANs, typically confined within office buildings, restaurants, stores, homes, etc. WLANs are gaining in popularity, fueled in part by the availability of devices optimized for wireless computing such as Intel® Centrino® Mobile Technology.

Wireless Wide Area Networks (WWANs) are the broadest range wireless networks. 3G is a WWAN that allows for high speed data transmission and greater voice capacity for mobile users. Next-generation cellular services based on various 3G technologies will significantly improve WWAN communications.

An access point is a bookend-size device that uses an RJ-45 port to attach to a 10BASE-T or 10/100 Ethernet network (if desired) and contains a radio transceiver, encryption, and communications software. It translates conventional Ethernet signals into wireless Ethernet signals it broadcasts to wireless NICs on the network and performs the same role in reverse to transfer signals from wireless NICs to the conventional Ethernet network.

Access points are not necessary for direct peer-to- peer networking (also called ad hoc mode), but they are required for a shared Internet connection or a connection with another network. When access points are used, the network is operating in the infrastructure mode.

NICs equipped for wireless Ethernet communications have a fixed or detachable radio antenna in place of the usual coaxial or Rj-45 port or dongle. Because a major market for wireless Ethernet use is note book computer user, a few vendors sell only PC Cards in their wireless Ethernet product lines, but most vendors support PCI cards for desktop computer. Most vendors also offer wireless USB adapters for use in both desktop and notebook computer. Because you can mix and match Wi-Fi certified products that use the same frequency band, you can incorporate any mix of desktop and notebook computers into your wireless network.

Wireless networks have different topologies, just as wired networks do. However, wireless networks use only two logical topologies:

Star, The star topology, used by Wi-Fi /IEEE 802.11-based products in the infrastructure mode, resembles the topology used by 10BASE-T and faster versions of Ethernet that use a hub. The access point takes the place of the hub because stations connect via the access point, rather than directly with each other. This method is much more expensive per unit but permits performance near 10BASE-T Ethernet speeds and easier management.

Point-to-Point, Bluetooth products (as well as Wi-Fi products in the ad hoc mode) use the point-to point topology. These devices connect directly with each other and require no access point or other hub-like device to communicate with each other, although shared Internet access with HomeRF does require that all computers connect to a common wireless gateway. The point-to-point topology is much less expensive per unit than a star topology. It is, however, best suited for temporary data sharing with another device (Bluetooth) and is currently much slower than 100BASE-TX networks.

Bluetooth is a low-speed (up to 700Kbps), low-power standard originally designed to interconnect notebook computer, PDA, cell phones, and pagers for data synchronization and user authentication in public areas, such as airports, hotels, rental car pickups, and sporting events. Bluetooth is also used for a wide variety of wireless devices on PCs, including printer adapters, keyboards and mice (Microsoft’s Bluetooth keyboard and mouse are available at many stores selling computer hardware), DV camcorder, data projectors, and many others. Bluetooth devices also use the same 2.4GHz frequency range Wi-Fi/IEEE 802.11b devices use. Unlike Wi-Fi, which is designed to allow a device to be part of a network at all times, Bluetooth is designed for ad hoc temporary networks in which two devices connect only long enough to transfer data and then break the connection.

The three major technologies used by wireless input devices are as follows:

• Infrared (IR)
• Proprietary radio frequency
• Bluetooth
  

All three technologies use a transceiver connected to the PS/2 or USB ports on the computer. Because many wireless transceivers are designed for use with a mouse and key board, PS/2-compatible versions have two cables—one for the mouse port and one for the keyboard port. A USB-compatible transceiver needs only one USB port to handle both devices if the system supports USB Legacy (keyboard) functions. The transceiver attached to the computer draws its power from the port.

The transceiver receives signals from the transceiver built in to the mouse or keyboard. These devices require batteries to function; therefore, a common cause of wireless device failure is battery run-down. Early generations of wireless devices used unusual battery types, but most recent products use off-the shelf alkaline AA or AAA batteries. Rechargeable batteries are usually not supported, although Logitech’s MX 700 has built-in rechargeable batteries and a transceiver that doubles as a charger.

If your wireless input device does work, check the following.

If you use the Internet, then you probably use Internet-based communications to contact family, friends or co-workers. From sending an instant message to a friend, to e-mailing co-workers, to placing phone calls, to conducting video conferences, the Internet offers a number of ways to communicate.

The advantages of Internet-based communications are many. Since you're already paying for an Internet account (or your employer is), you can save money on phone calls by sending someone an instant message or by using VoIP instead of standard local telephone services. Of course, no technology is without a downside and Internet-based communications has plenty, such as viruses, privacy issues and spam. Read more...

There is no doubt that by registering and using a domain name your costs associated with having a Web site will increase. Many individuals will use domain names to help create an identity on the Web, but for most business and corporate users, the use of a domain name is for branding purposes. Usually, you will try to find a domain name that is related to your company name, your industry, or a mixture of both if finding an available domain name becomes too difficult. Companies will often use their Web site as a way to communicate and provide information to clients, and also market their Web site as a part of their business by including the URL to their Web site on business cards and advertisements. Read more...

Even though most new PCs purchased at retail include some type of dialup modem you can use for Internet and email access, you are likely to find that Internet and email access with a dialup modem aren’t sufficient for your needs if you use these services for more than a few minutes each day. Read more...

DSL takes advantage of the broadband nature of the telephone system, suing the system’s capability to carry signals at multiple frequencies to allow both high-speed Internet traffic and phone calls at the same time. Read more...

For users with high bandwidth requirements (and deep pockets), dedicated leased lines provide digital service between two locations at speeds that can far exceed ISDN and are as fast or faster than DSL or cable modem. A leased line is a permanent 24-hour connection to a particular location that can be changed only by the telephone company. Businesses use leased lines to connect LANs in remote locations or to connect to the Internet through a service provider.

The most common blunder people make when the topic of a computer virus arises is to refer to a worm or Trojan horse as a virus. While the words Trojan, worm and virus are often used interchangeably, they are not the same. Viruses, worms and Trojan Horses are all malicious programs that can cause damage to your computer, but there are differences among the three, and knowing those differences can help you to better protect your computer from their often damaging effects. Read more...

Adware is considered a legitmate alternative offered to consumers who do not wish to pay for software.
Spyware is considered a malicious program and is similar to a Trojan Horse in that users unwittingly install the product when they install something else. A common way to become a victim of spyware is to download certain peer-to-peer file swapping products that are available today. Read more...

VoIP allows you to make telephone calls using a broadband Internet connection instead of using a regular analog phone line. Some services using VoIP may allow you to call only other people using the same service, but other services will allow you to call anyone who has a telephone number — including local, long distance, mobile, and international numbers. Also, while some services work only over your computer or a special VoIP phone, still, other services allow you to use a traditional phone through an adaptor. Read more...

The Internet is a massive network of networks, a networking infrastructure. It connects millions of computers together globally, forming a network in which any computer can communicate with any other computer as long as they are both connected to the Internet. Information that travels over the Internet does so via a variety of languages known as protocols.

The World Wide Web, or simply Web, is a way of accessing information over the medium of the Internet. It is an information-sharing model that is built on top of the Internet. The Web uses the HTTP protocol, only one of the languages spoken over the Internet, to transmit data. Web services, which use HTTP to allow applications to communicate in order to exchange business logic, use the Web to share information. The Web also utilizes browsers, such as Internet Explorer or Netscape, to access Web documents called Web pages that are linked to each other via hyperlinks. Web documents also contain graphics, sounds, text and video.

The Web is just one of the ways that information can be disseminated over the Internet. The Internet, not the Web, is also used for e-mail, which relies on SMTP, Usenet news groups, instant messaging and FTP. So the Web is just a portion of the Internet, albeit a large portion, but the two terms are not synonymous and should not be confused.

The two types of monitor technologies available to consumers are available in CRT monitors and LCD monitors. There are big differences between LCD and CRT, and while LCD technology has advanced to the point where its viewing quality is comparable to CRTs, many people today still choose to purchase a CRT monitor. CRTs are bigger and bulkier than an LCD, they consume more power and are prone to screen flicker. LCD monitors, however, are more expensive when compared to CRTs, they introduce the problem of viewing angles, and generally have less accurate color replication. Read more...

From producing business documents to greeting cards to photos, color printers have changed the way we work and print at home and in the office. In fact, color printers are such a common computer accessory that today many retailers even offer a free one when you purchase a computer.

Traditionally, color laser printers were kept in the workplace while inkjet printers were the popular choice for home and home-office users. With the ever-improving printer, toner and ink technology, along with the drop in prices on different types of printers, you now have more choices now than ever. Read more...

To make things even more muddled, AMD and Intel each offers multiple families of processors ranging from those designed for value-oriented family PCs to powerhouse CPUs designed to run most tasking 3D games smoothly. Added into the mix are a host of additional featuresis as well as a new selection of dual-core processors designed for 32-bit or 64-bit computing.

If you find yourself looking through computer store flyers and wondering exactly what an "Athlon 64 X2" is or what the difference between a Pentium 4 and a Pentium D is, then this is a good place to start. We provide an overview of some of the newer and more common families of processors from Intel and AMD. Read more...

With so many different formats — DVD+R, DVD+RW, DVD-RAM, DVD-R, DVD-RW, DVD-ROM — how do users know which DVD format is compatible with their existing systems, and why are there so many different formats for DVDs? The following information sheds some light on DVD's different flavors, the differences between them and the incompatibility issues that the differing technologies have sprouted. Read more...

Format actually means to prepare a storage medium, usually a disk, for reading and writing. When you format a disk, the operating system erases all bookkeeping information on the disk, tests the disk to make sure all sectors are reliable, marks bad sectors (that is, those that are scratched or otherwise damaged), and creates internal address tables that it later uses to locate information. You must format a disk (floppy or hard disk) before you can use it. Read more...

The differences between a software and hardware firewall are vast, and the best protection for your computer and network is to use both, as each offers different but much-needed security features and benefits. Updating your firewall and your operating system is essential to maintaining optimal protection, as is testing your firewall to ensure it is connected and working correctly. Read more...

Think of a bus as the electronic highway on which data travels within a computer, from one component to another. Basically, it's the conduit used by your entire system to communicate with your CPU. A bus is a collection of wires and connectors through which the data is transmitted. When used in reference to personal computers, the term bus usually refers to what is commonly called the local bus (on older systems) or system bus (on newer systems). This bus is considered the first bus on the electronic highway and it connects the CPU to the main memory (RAM) on the motherboard. All buses consist of two parts -- an address bus and a data bus. Read more...

A video adapter is board that plugs into a personal computer to give it display capabilities. Those capabilities of a computer, however, depend on both the logical circuitry (provided in the video adapter) and the display monitor. A monochrome monitor, for example, can't display colors no matter how powerful the video adapter.. Read more...

All hard drives share a basic structure and are composed of the same physical features. However, not all hard drives perform the same way as the quality of the parts of the hard drive will affect its performance. Following is a description of the common features of the hard drive and how each part works in relation to the others. Hard drives are extremely sensitive equipment and the internal workings of a hard drive should not be handled by anyone other than an experienced professional. Read more...

Have you ever wondered what all those numbers mean when you go to buy a CD burner? When you see a configuration that looks like 12x2x24 (three numbers separated by the letter "x"), these numbers indicate the drive speeds of the CD drive. The "x" stands for the transfer of 150 KB of data per second, and each number represents a different action that the CD drive can take. A CD-R drive has two actions -- recording onto and reading from compact discs. A CD-RW drive has three actions -- recording, rewriting (erasing and recording over) and reading. When looking at the drive speeds, the first number ("12" in the above example) indicates the speed at which the CD drive will record data onto a CD-R compact disc. So, in the above example, the CD drive will record data at 12 times 150 KB/second. The second number ("2" in the above example) indicates the speed at which the CD drive will rewrite data onto a CD-RW compact disc. So in the above example, the CD drive will rewrite data onto the compact disc at 2 times 150 KB/second. Typically, the second number, the rewrite speed, is lower than the first number, the write speed, because rewriting is a slower process than writing. The last number ("24" in the above example) indicates the speed at which the drive will read data from a compact disc. So in the above example, the CD drive will read data from a compact disc at 24 times 150 KB/second.

Any time that a file is deleted from a hard drive, it is not erased. What is erased is the bit of information that points to the location of the file on the hard drive. The operating system uses these pointers to build the directory tree structure (the file allocation table), which consists of the pointers for every other file on the hard drive. When the pointer is erased, the file essentially becomes invisible to the operating system. The file still exists; the operating system just doesn't know how to find it. It is, however, relatively easy to retrieve deleted files with the right software.

The only way to completely erase a file with no trace is to overwrite the data. The operating system will eventually overwrite files that have no pointers in the directory tree structure, so the longer an unpointed file remains in the hard drive the greater the probability that it has been overwritten. There are also many "file erasing" software products currently on the market that will automatically permanently erase files by overwriting them.

Computer failures occur for a variety of reasons, sometimes because of human error and sometimes because of factors in the environment that cause a computer to malfunction (or a combination of human and environmental factors). These factors can include excessive buildups of dust, heat or magnetism; viruses picked up from the Internet or from storage media shared between different computers; static electricity shocks or power surges; carelessness, such as spilling liquids into a computer or bumping or dropping the hard drive casing; software that has not been configured correctly or a PC's setup that has been handled incorrectly; incorrect handling of upgrades.

The typical computer system boots over and over again with no problems, starting the computer's operating system (OS) and identifying its hardware and software components that all work together to provide the user with the complete computing experience. But what happens between the time that the user powers up the computer and when the GUI icons appear on the desktop?. Read more...

The system registry is one of the most important parts of a Windows-based computer system. Not to be tampered with lightly, the registry is a system-defined database used by the Windows operating system to store configuration information. Most Windows applications write data to the registry during installation, and system components store and retrieve configuration data through the registry. The data stored in the registry varies according to the version of Microsoft Windows. Read more...

Direct X is a set of APIs (application program interfaces) developed by Microsoft. It provides software developers with resources to write Windows-based applications that access hardware features of a computer without knowing exactly what hardware will be installed when the program eventually runs. By using the interfaces provided by DirectX, software developers can take advantage of hardware features without being concerned about the implementation details of that hardware.

The full benefit of DirectX is most evident in PC games. Unlike console gaming machines such as the PlayStation or GameCube, for example, computer game developers are producing a game that needs to be designed to work well on a variety of systems — as opposed to one system that is the same for all end-users.