access point—The hub through which different devices using the network communicate in an 802.11 wireless LAN (local-area network).

active-matrix display—The better of the two major types of LCD technologies used in notebook computers. An active-matrix display uses individual transistors to control and adjust each pixel (a picture element; the tiny dots that make up a video display). This creates a sharp, easy-to-view display that makes using a notebook computer more comfortable for your eyes. Active-matrix displays are much better than the older, less expensive passive-matrix displays. Active-matrix displays are also known as TFT (thin film transistor) displays.

AGP (Accelerated Graphics Port)—This port enables the graphics controller to communicate with the computer and access its main memory. The AGP is a high-speed port designed to handle 3D technology and store 3D textures in the main memory rather than the video memory.

CD-ROM (compact disc, read-only memory) drive—A data storage device that reads CD-ROMs. These drives are standard on many PCs and are available in various speeds represented as multiples of X.

CD-RW (compact disc-rewriteable) drive—A CD-based drive that can read, record, or erase data on the surface of special CDs.

Centrino—The name for the generation of mobile processors to follow Intel's Mobile Pentium 4-M processor. Centrino features the previously code-named Banais mobile processor designed from the ground up for notebook computers. Centrino, however, adds additional elements and benefits to Banais, including wireless chipsets and more efficient power management.

chipset—A collection of microchips that work together to perform a specific function such as controlling a computer's graphics display or communicating with other computers over telephone lines. The term most commonly refers to several microchips attached to a computer's motherboard that direct data traffic between its CPU, memory, and peripheral devices.

CPU (central processing unit)—The "brain" or control unit of every PC. A CPU is a silicon microprocessor chip that deciphers and initiates your commands and preprogrammed software commands. The clock speed of a CPU, expressed in megahertz, determines how fast it can perform the millions of calculations necessary to accomplish basic computing tasks.

DDR SDRAM (double-data-rate synchronous dynamic random-access memory)—This type of memory effectively has twice the data transfer rate of standard SDRAM, because it executes two instructions per cycle rather than one.

DIMM (dual in-line memory module)—A circuit board that contains multiple memory chips. These boards are inserted into memory expansion slots to increase a computer's RAM. DIMMs support 64-bit and higher buses and ones with 168 pins.

docking station—A device that acts as a terminal to connect a portable computer to other equipment, such as a network or a desktop monitor and keyboard.

DRAM (dynamic random-access memory)—A type of computer memory that is widely used in PCs because of its low price.

DSTN (double-layer supertwist nematic)—A passive-matrix LCD technology. DSTN LCDs use two display layers to deal with the color shifting that can occur with single-layer supertwist nematic (also known as color supertwist nematic), passive-matrix displays. Supertwist LCDs create images by twisting light rays to produce the desired color and brightness in each pixel that makes up the screen. DSTN LCDs are not as bright as active-matrix displays, and they can be difficult to view from angles other than straight ahead.

DVD (digital versatile disc) drive—An optical data storage device that can read audio and software CD-ROMs and DVDs. Each DVD is capable of storing 4.7GB (gigabytes) or more of data. Notebooks sometimes offer a DVD recordable drive, which uses recordable media, usually specific to the drive type, such as DVD-R, DVD-RAM, DVD-RW, DVD+RW, and DVD+R.

Ethernet—The most commonly used LAN protocol. The Ethernet standard specifies how networked computers communicate with one another. Common Ethernet networks support data transfer rates of 10Mbps (megabits per second) or 100Mbps, although the newest variety, called Gigabit Ethernet, can support transfer rates of up to 1Gbps (gigabit per second), or 1000Mbs.

GHz (gigahertz)—A measurement used to gauge the speed of a CPU. One gigahertz is equivalent to 1 billion clock cycles per second.

graphics accelerator—A video adapter that has its own processor to enhance performance. These accelerators are designed to handle high-end graphics applications, leaving the CPU to perform other computing tasks. Accelerators typically come with their own conventional DRAM, or a special, faster type of VRAM (video RAM). The graphics chipset or video control chipset that resides on an expansion card in a desktop PC is often affixed directly to the motherboard of a notebook PC to save space.

hard drive—The primary data storage device in most desktop and notebook PCs. Hard drives are fixed magnetic disks that a computer can read, erase, and write large amounts of data to as often as necessary. A hard drive stores a PC's operating system, other installed programs, and user files.

hotspot—A location that provides wireless Internet service via a wireless access point. Hotspots are usually in populated public areas, such as a town square or downtown area, as well as at hotels and airports. In some instances, users may have to pay for access whereas other hotspots provide free access.

HPA (high-performance addressing)—A passive-matrix display technology that provides sharper contrast and better picture quality than traditional passive-matrix LCDs. HPA LCDs generally don't approach the image quality of active-matrix displays, but they are much cheaper to produce.

IEEE 1394 (FireWire)—A specification for a new, high-speed external bus used to connect computer peripherals and has transfer speeds of up to 400Mbps.

IEEE 802.11—A wireless standard defined by the IEEE (Institute of Electrical and Electronics Engineers). The 802.11 specification is an extension of the 802 group of specifications defining standards for LANs. IEEE 802.11 allows for wireless LANs and provides a framework for different manufacturers to create new products that can interact with each other.

infrared (IR)—A band of electromagnetic waves slightly below the frequency of visible light. Infrared connections can be used for data swapping between PCs and peripherals. The peripheral device, such as a PDA, sends an infrared beam of light to a receiving device, such as a notebook computer to sync information. Because infrared devices use light beams, any obstruction in the path between the remote and receiving device will result in signal distortion or signal loss.

KB (kilobyte)—A measurement of data storage equivalent to 1,024 bytes or approximately 1,000 characters of information.

Kbps (kilobits per second)—A unit of measurement for the speed of data transmission (1Kbps is equivalent to 1,024 bits per second).

keyboard—The main input device for a PC that is similar to an electric typewriter keyboard with a few extra keys for various computing functions.

L1 (Level 1) cache—Also known as primary cache, this type of memory is much faster and more efficient than normal RAM. L1 cache is usually directly on a microprocessor and stores information that is frequently accessed.

L2 (Level 2) cache—Also known as secondary cache, this type of memory is increasingly being moved to the CPU core. L2 caches are used to supplement L1 cache and are generally larger but slower to access.

L3 (Level 3) cache—A tertiary cache sometimes located on the motherboard but also found on the CPU die, away from the core, that helps to speed up memory operations.

LCD (liquid-crystal display)—A flat, lightweight display technology used in notebook computers. Special molecules in the screen have the ability to bend and twist light to create desired images. There are two main types of LCDs in notebooks today: passive-matrix displays and active-matrix displays.

Li-Ion (lithium-ion) battery—The newest of the rechargeable notebook battery technologies. Compared to other battery types, Li-Ion generally offers the longest run times for the least amount of weight. They are often more expensive, however, than the older NiMH batteries, which means manufacturers often use them in premium-priced notebook computers.

Mb (megabit)—A unit of data measurement equivalent to approximately one million bits. Bits are typically represented in computer terminology by a lowercase b.

MB (megabyte)—Also referred to as a "meg," this is a measurement of computer storage that equals 1,048,576 bytes. An uppercase B typically represents bytes in computer terminology.

MHz (megahertz)—A measurement used to gauge the speed of a CPU. Smaller electronic devices, such as PDAs, still feature CPUs slower than 1GHz. One megahertz is equivalent to 1 million clock cycles per second.

microprocessor—An integrated circuit known as the CPU that controls a computer.

modem—Acronym for modulator/demodulator. A communications device that lets a computer transmit data over analog telephone lines by exchanging digital signals for analog signals. Modem speeds are expressed in kilobits per second. The fastest modems typically found in today's computers are capable of transmitting information at speeds of up to 56.6Kbps.

modular device bay—A bay on the front or side of a notebook PC that can accommodate a variety of devices such as CD-ROM or DVD drives, diskette drives, batteries, hard drives, Zip drives, or LS-120 SuperDisk drives. Modular device bays make it easy for users to upgrade their notebooks or leave behind devices they don't need. Modular bay options vary depending on a notebook's brand and model.

motherboard—A circuit board inside a computer that provides the foundation for the system. The motherboard holds all the internal circuitry for the system, such as the CPU, buses, memory sockets, and expansion slots.

MPEG (Moving Picture Experts Group)—A group of approximately 300 experts from 20 countries that meet three times a year to create international standards for the compression, decompression, processing, and coded representation of moving pictures and audio. MPEG is also used as the name of the various standards the Group creates, including MPEG-1 (storage and retrieval of moving pictures and audio on storage media), MPEG-2 (digital television), and more.

NIC (network interface card)—An expansion board that allows the computer to connect to a network.

NiMH (nickel-metal hydride) battery—This rechargeable notebook battery technology replaced the once prevalent nickel-cadmium batteries and offers better, longer charge times. Good performance and reasonable prices make NiMH batteries a popular choice for many notebook computer manufacturers. Most experts, however, consider Li-Ion batteries to have the superior technology.

OS (operating system)—Software that controls a computer's basic functions and acts as a foundation to run additional programs. Operating systems recognize keyboard input, send the output to monitors and printers, control peripheral devices, handle system security, and keep records of files and directories. Microsoft Windows 98, Windows NT 4.0, and Windows 2000 are examples of operating systems.

passive-matrix display—The older, cheaper, and less-desirable type of the two major types of LCDs used in notebook computers. A passive-matrix display uses a series of crisscrossed wires to create pixels at the wire intersections. An active-matrix display uses individual transistors to control each pixel; a passive-matrix display simply signals each pixel whether to let light pass through it. This creates a fuzzy, slow refreshing display that can cause users discomfort after long periods of use. The only benefit of passive-matrix displays (and the slightly superior, faster-refreshing dual-scan passive-matrix displays) is they have generally been considerably cheaper than the active-matrix ones (although this is beginning to change as new active-matrix technologies and manufacturing methods advance). Today, passive-matrix displays are rare among notebook PCs. If you do find them, however, they will most often be in value-priced units.

PC Card—A credit card-sized device you insert into the PC Card slot of a notebook computer to increase its functionality. Three types of PC Cards and PC Card slots exist: Type I is usually for memory upgrades; Type II is usually for modems or peripheral connections, such as an external CD-ROM drive; and Type III is usually for a portable hard drive.

PCI (Peripheral Component Interconnect)—An Intel-designed bus that facilitates quick communication between a peripheral and the computer's CPU. PCI buses let users install additional peripherals to a system and support Plug-and-Play capabilities.

pointing stick—An input device commonly used in notebook computers because an external mouse is unwieldy for mobile use. A pointing stick generally looks like the eraser tip of a pencil, and it sits somewhere in the keyboard, usually nestled in the middle of the G, H, and B keys. A pointing stick works in conjunction with buttons in the wrist rest. These buttons act like the buttons found on mice. Also called a trackstick.

ports—Multipin male or female connectors that enable users to connect external devices, such as monitors and printers, to a computer.

PS/2 port—A port used for connecting an external mouse or keyboard to a notebook.

RAM (random-access memory)—A temporary workspace for data. Computers use RAM to hold information they are processing. The more RAM a computer has, the less time the CPU has to wait while data is accessed from its hard drive. Therefore, the amount of RAM determines the size and number of programs that users can simultaneously run and how those programs will perform.

RDRAM (Rambus dynamic random-access memory)—A type of memory developed by Rambus that dramatically increases the speed at which data is transferred. RDRAM is expected to replace the present standard of memory, SDRAM (synchronous dynamic random-access memory).

resolution—A term that refers to the amount of sharpness and clarity of an image. High-resolution devices produce sharper, more defined images. Video display resolution is often measured in pixels or dots per inch, expressed as the number of dots it can produce on each distinct line. In other words, a 15-inch display running at 640 x 480 displays 640 dots on each of 480 lines (307,200 pixels).

RJ-11 (Registered Jack-11)—A typical telephone jack in the United States. RJ-11 is a modular, 4- to 6-wire male connector that attaches to a female connector.

RJ-45 (Registered Jack-45)—A type of connector commonly used for communications connections, such as network and Internet services. RJ-45 connectors are slightly larger than RJ-11 telephone connectors.

SDRAM (synchronous dynamic random-access memory)—A type of computer memory that provides faster access than standard DRAM by synchronizing its functions with a computer's internal clock.

smart battery—A portable computer battery that keeps its system up-to-date about its power status. Also called an intelligent battery.

sound card—An expansion board (or chipset on the motherboard in the case of a notebook) that provides a PC with audio capability.

SVGA (Super Video Graphics Array)—Used to define the display resolution of 800 x 600 (800 horizontal pixels by 600 vertical pixels) or higher.

SXGA (Super Extended Graphics Array)—Used to define the display resolution of 1280 x 1024 (1280 horizontal pixels by 1024 vertical pixels).

touchpad—A pointing device used in notebook computers. A touchpad is a pressure-sensitive device that usually sits in the wrist rest. You control the on-screen pointer by dragging your finger across the pad. Generally, one or two buttons are under the touchpad for clicking items. You also can simply lift your finger and tap the pad itself. A touchpad is also known as a trackpad.

USB (Universal Serial Bus)—An external bus standard that is expected to eventually replace serial and parallel ports for adding peripherals to a system. The present USB standard, USB 2.0, will support data transfer rates of up to 480Mbps, plug-and-play installations, hot swapping (adding or disconnecting a device without powering down or rebooting a PC), and is backward compatible with USB 1.1. USB also lets users connect up to 127 devices to one port.

UXGA (Ultra Extended Graphics Array)—Used to define the display resolution of 1600 x 1200 (1600 horizontal pixels by 1200 vertical pixels).

V.92—A dial-up modem specification with upload speeds of 48Kbps and download speeds of 56.6Kbps.

VGA (Video Graphics Array)—Used to define the display resolution of 640 x 480 (640 horizontal pixels by 480 vertical pixels).

VRAM (video RAM)—A special, more expensive type of RAM chip that can perform reads and writes at the same time, making it faster than DRAM. Video adapter manufacturers place VRAM chips, which enhance graphics performance, on video adapters to speed the creation of on-screen images.

Wi-Fi—A wireless technology standard, short for wireless fidelity, set by the Wireless Ethernet Compatibility Alliance (WECA) to ensure compatibility of 802.11a, b, and g wireless equipment.

WXGA (Wide Extended Graphics Array)—Used to define the display resolution of 1366 x 768 (1366 horizontal pixels by 768 vertical pixels), which has an aspect ratio of 16:9.

XGA (Extended Graphics Array)—Used to define the display resolution of 1,024 x 768 (1024 horizontal pixels by 768 vertical pixels).

Zip drive—A storage device designed by Iomega that can store 100MB or 250MB of data on special diskettes only slightly larger than standard 1.44MB diskettes. Zip drives are commonly used for storing, transporting, and backing up date files.

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