ATAPI
ATAPI (AT Attachment Packet interface) is an extension of EIDE, which allows support for CD-ROM drives and other devices, such as tape drives.

ATC or Advanced Transfer Cache
Advanced Transfer Cache (ATC) refers to the speed of the CPU's L2 (level 2) cache. L2 cache is a small amount of high-speed memory on or near the CPU, which increases the system's performance. Depending on the processor and motherboard, the speed of the L2 cache may either run at the same speed as the processor, or it may run at half-speed or less. ATC (a term coined by Intel) means that the L2 cache runs at the full processor speed.

ATX
ATX refers to the size or "form factor" of a motherboard. ATX is a widely used standard. In addition to ATX, there is the MicroATX form factor. The size or form factor of a motherboard usually dictates the number of slots that can be included on the motherboard. An ATX motherboard normally has 5 or 6 PCI slots and 3 DIMM (memory) slots as compared to the MicroATX form factor, which normally has 3 PCI slots and 2 DIMM slots.

AGP or Accelerated Graphics Port
AGP (Accelerated Graphics Port) is today's standard for connecting a graphics card to a PC's motherboard. This technology was developed to handle the high data-throughput needs of 3D graphics cards. Prior to the advent of AGP, most graphics cards were connected using the PCI slot (many still use PCI). AGP has many advantages, including a direct connection with the system's main memory and a much higher bandwidth. AGP is available in three levels: AGP 1X, AGP 2X and AGP 4X. Please refer to the Video Card section of The TigerDirect.com Online University for details on AGP.

BIOS
Your PC's BIOS (Basic Input Output System) is the software program that actually boots (or starts up) the computer. The BIOS contains all the required information to control the flow of data between the computer's operating system and devices such as the hard drive, video card, keyboard, mouse, etc. The BIOS is an essential part of the PC and is built into the motherboard. In the past, the BIOS was located on a ROM (Read Only Memory) chip, and could not be accessed by the user. However, many newer motherboards place the BIOS in a flash ROM chip where upgrading is possible.

BACK SIDE BUS
This is the data path between the system's processor (CPU) and the L1 or L2 cache. It runs at the PCs core clock speed, and is the fastest bus in your computer.

BANDWIDTH
This term describes the amount of data that can flow across an interface, measures in megabytes per second.

BUFFER UNDERRUN ERROR
This is a problem which occurs with some CD-RW drives when a "gap" develops in the stream of data to be written to a disc. This interruption in information flow usually ruins the recording session and renders the CD unusable. This error can be avoided buy selecting a CD-RW drive that include "Buffer Underrun Protection," now available with many models.

BUS
A system's "bus" is a path along which data travels inside your PC. A bus is used to link the system's main memory with devices installed, drives, adapter cards and the processor. Any give bus may have a different width and speed, depending on its tasks. The capabilities of a bus are measured in bandwidth---megabytes per second.

CD BURNER
Slang term for CD-RW drive.

CD-R or Compact Disc-Recordable
This is a disc (like an audio CD) onto which data can be recorded. A CD-R differs from a CD-RW in that it cannot be erased and re-written. A CD-R drive is used to record data onto a CD-R media disc.

CD-ROM or Compact Disc-Read Only Memory
This is a disc (like an audio CD) which contains information that can be read only. It is locked and cannot be re-written or edited. A CD-ROM drive is used to read CD-ROM discs.

CD-RW or Compact Disc-Rewritable
This is a disc (like an audio CD) onto which data can be recorded, erased and re-recorded. You must use a CD-RW drive and CD-RW media to record data, erase it and re-record on it.

CPU
The CPU, or Central Processing Unit, is typically though of as the computer's brain. It is the device inside a computer that processes data, per the instructions by the software. A CPU's three primary functions are:
* Performing mathematical calculations
* Logical comparisons
* Data manipulation

One note about CPUs: While it is true that the CPU is the brain of the system, it is in fact, the microchip, or the microprocessor which is inside the CPU that does the work. The CPU also contains the L1 cache and often the L2 cache.

CHIP
There are various types of chips in use in today's computers. There are CPU chips, memory chips among others. Chips are crafted from semi-conductiong material, normally silicon, and have an integrated circuit embedded into them. Chips are responsible for the computer revolution, and a typical chip contains millions of transistors. Most chips are no larger than 1/4 inch, and a computer may contain dozens of chips.

CORE CLOCK SPEED
This is the speed at which a CPU operates. A CPU's core clock speed is measured in Megahertz (MHz) or Gigahertz (GHz) The core clock speed is the number seen in computer descriptions, such as "Intel Pentium III 600MHz."

CYRIX
A CPU manufacturer, recently acquired by VIA.

DDR SDRAM or Double Data Rate SDRAM
A type of Synchronous DRAM memory, which can transfer data on both the "rising" and "falling" edges of the clock cycle, as opposed to just the rising edge as with single-dat rate SDRAM. The result is twice the data throughput. DDR SDRAM must be supported by the motherboard.

DIMM or Dual Inline Memory Module
This is the "packaging" format for SDRAM memory. A DIMM is comprised of one or more RAM (Random Access Memory) chips, which is on a circuit board with pins on one edge that plug into the DIMM sockets on the motherboard. One DIMM can be used in place of two SIMMs (Single Inline Memory Module). The DIMM format is now the dominant form of memory packaging, replacing the older SIMM format.

DVD-RAM DRIVE
A drive that records onto high-capacity DVD discs.

DISK CACHE
Hard drives include this type of cache ( a small amount of memory) that is used to store recently accessed data, or data that is likely to be accessed soon. By keeping this type of frequently-accessed data handy, and reducing the amount of time needed to access it, the hard drive performance is greatly improved.

DRIVER
A program written for a specific device, such as a video card, mouse or printer. A driver contains special knowledge about the device, and helps other programs work with it.

DRIVE BAY
A slot or opening in a PC's case into which a drive (hard drive, CD-ROM, CD-RW or DVD) is installed.

EIDE or Enhanced Integrated Drive Electronics
This ia a standard interface used to connect drives to a computer. EIDE is an enhanced version of the older IDE standard (though you may notice that these terms are sometimes used interchageably). Also, EIDE is sometimes referred to as "ATA." ATA is a more specific name for EIDE. There are several varieties of ATA (i.e.: ATA/33, ATA/66 and ATA/100). The numbers refer to the amount of data that can be transferred, measured in megabytes per second (MB/sec.). There is another popular interface for connecting drives is SCSI (Small Computers System Interface). Currently, most PC motherboards are equipped with EIDE interfaces, since EIDE is the dominant drive type. EIDE is generally less expensive, and is easier to configure. For a more detailed comparison of EIDE and SCAI, wee the hard drive section of the TigerDirect.com Online University.

ETHERNET
The most common LAN (Local Area Network) technology.

EXPANSION CARD
A card with a specific capability, like a video card or sound card, which is inserted into an expansion slot in the computer's motherboard.

EXPANSION SLOT
The slot in a motherboard into which an expansion card (Video card, Sound card) is inserted, adding additional capability to the computer system. There are different types of expansion slots, most commonly PCI or the newer AGP.

FC-PGA or Flip Chip-Pin Grid Array
This is a type of processor "packaging" used by Intel for their Celeron and Pentium III "Coppermine" CPUs. CPUs with FC-PGA pacaging van be connected to motherboards with a Socket 370. FC-PGA-packaged CPUS may also be referred to as Socket 370, FC-370.

FAN AND HEATSINK
Today's CPUs produce an enormous amount of heat (mainly because of the physical nature of silicon), and must be cooled to avoid overheating and damage to delicate components inside your computer. Today's powerful CPUs must always be installed with a fan and heatsink to keep the system at a cool temperature.

FIREWIRE or IEEE 1394
FireWire is a high-performance serial bus with a data transfer rate of 400 Mbps (Megabits per second). The name "FireWire" is a trdemark of Apple Computer. IEEE 1394 products from other companies have been given different names, "iLink" for example. Like USB, FireWire supports Plag and Play and "hot plugging." However, FireWire delivers a substantially higher transfer rate, and is much more expensive. FireWire is commonly used with peripherals requiring "real time" data throughput, such as video devices.

FIRMWARE
Firmware is basically software that is incorporated directly into a piece of hardware. Firmware is typically found in printers, modems and other PC peripherals.

FOOTPRINT
The amount of space occupied by a piece of equipment when placed on a desktop.

FORM FACTOR
Commonly used to describe the size (or physical arrangement) of a PC motherboard or case. Today's standards are ATX and the slightly smaller MicroATX.

FRONTSIDE BUS or FSB
Also referred to the "system bus." The Frontside Bus is the data path connecting the CPU and the system's main memory, or RAM. The Frontside Bus constantly carries information between the CPU and memory to complete tasks, and is the most important bus in your computer.

GB or GIGABYTE
One GB is equivilant to one million bytes. A GB is the term used to express the capacity of a hard drive (i.e.: a 10GB hard drive).

GBps
Gigabytes per second

GIF
An image format, smaller and less detailed than a JPEG image. Typically, GIF images are used on the web because they are smaller and require less time to download.

GPU or GRAPHICS PROCESSING UNIT
A term introduced by nVidia, currently the leading manufacturer of graphics chips. A GPU is similar to a CPU, but is designed specifically for the purpose of processing graphics. While many graphics cards required processing help from the PC's CPU, a GPU reduces the CPU's workload, freeing it for other processing tasks.

GRAPHICS CARD
A card or board which includes the graphics circuitry required to view 2D or 3D gaphics on your computer screen. A graphics card is connected to to a computer's motherboard through a PCI or AGP slot (some motherboards have graphics capabilities onboard). Graphics cards are avialble in many varieties; some enable 2D graphics, some 3D graphics, some enable both 2D and 3D.

GRAPHICS PROCESSOR
Graphics processors are often found on high-end graphics cards. A graphics processor is similar to a CPU, but works exclusively on processing graphics.

HARD DRIVE
Also known as a hard disk drive, is a device inside the computer which stores all data and programs. When you command the PC to "save" file, the information is written on a disk inside the drive. When you command the PC to "open" a file, the information is retrieved and displayed. Hard drives can be internal (installed inside the PC) or external (installed in a housing that is connected to the PC).

HARD DISK DRIVE
The more accurate term for a "Hard Drive." The "disk" is where the information is written to, stored and from which it is retrieved.

IEEE 94 or FIREWIRE
See FireWire.

I/O
Input/Output

ISA or INDUSTRY STANDARD ARCHITECTURE
An older standard (bus) for connecting expansion cards such as video cards and sound cards to a computer. The ISA standard bus has been replaced by the PCI bus, which hs a higher bandwidth. ISA is still in existence, and many motherboards still include at least one ISA slot.

INTERFACE
An interface, when refering to computers, enables different parts of the computer system to communicate. Common interfaces include EIDE and SCAI (which enable the PC's drives, CPU and memory to communicate), or the GUI (Graphical User Interface) which enables the user to interact with the computer.

KB
Kilobyte

KBps
Kilobytes per second (KBps is a measurement of bandwidth).

Kbit
Kilobits

L1 CACHE
A small amount of high-speed memory located on the CPU. The L1 cache stores frequently used data so that it won't have to be accessed from the main memory. The L1 cache helps to speed up processing tasks. The size and speed of the L1 cache can have a dramatic impact on the system's performance.

L2 CACHE
A small amount of high-speed memory located near---or on---the CPU. Frequently accessed data is stored on the L2 cache, which improves performance by eliminating the need to access the data from main memory. Like L1 cache, the size and speed of L2 cache can have a dramatic impact on system performance.

LAN or LOCAL AREA NETWORK
A group aof computers, connected to each other (and in some cases, a server) in a specific area, like an office or building. When connected to a LAN, these computers can share information, applications and peripherals (like printers). A LAN can range from two connected PCs to thousands.

MIPS
MIPS (Millions of Instructions Per Second) is a measurement of CPU performance.

MPEG
A type of digital video compression, developed by the Motion Picture Experts Group. MPEG is a format which incorporates a technique of storing only the changes from one frame of the video sequence to another, rather than storing the entire frame. Currently, there are two MPEG standards (MPEG-1 and MPEG-2).

MPEG-1 has a resolution of 352 x 240 at 30 frames per second (fps). MPEG-1 delivers video quality slightly less than that of VHS video tapes.

MPEG-2 offers resolutions of 720 x 480 and 1280 x 720 at 60fps, including full CD-quality audio. MPEG-2 meets the NTSC and HDTV standards. MPEG-2 can compress a two-hour video into just a few gigabytes, and is used when recording DVD-ROMS. Decompressing MPEG-2 data requires very little computing power, however, encoding video in MPEG-2 does require significant computing power.

MTBF or Mean Time Between Failure
This is a measurement of how likely a hard drive or printer is to fail within the first few hours of operation. Usually an MTBF will be a very large number, such as 400,000 hours. This means that all hard drives (of a similar class or manufacturing specification) that were tested by the manufacturer before shipping, experienced one failure per 400,000 hours of testing. Most individual drives, however are tested for only an average of two hours. MTBF is a technical measurement of reliability. For consumers, we recommend checking the manufacturer's service policies and warranties.

MAIN MEMORY
The system's main memory stores all the necessary data and instructions that the PCU needs to complete the requested operations. The CPU and the main memory communicate via the "system bus," which is a pathway over which information travels. In today's PCs, SDRAM is the most common type of memory (although the faster DDR SDRAM is gaining popularity). The main memory is used for short-term storage, and information is held in main memory until you turn off your PC (as opposed to a hard drive, which is used for long-term storage). Memory allotments in moden PCs ranges from 32MB to 256MB, although more is possible.

MEMORY BUS
This is a pathway between the memory controller (located on the motherboard's chipset) and the system's main memory (RAM), which is also located on the motherboard.

MicroATX
MicroATX is a motherboard form factor, and is slightly smaller than the popular ATX form factor. MicroATX motherboards fit into MicroATX PC cases, and have a smaller footprint than ATX cases. The space-savings does come at a cost: they usually include only 2 DIMM slots and 3 PCI slots. In contrast, ATX motherboards typically include 3 DIMM slots and 5 PCI slots.

MICROPROCESSOR
The microprocessor is commonly referred to as the CPU, and is responsible for performing operations which are requested by the programs. The microprocessor is responsible, in large part, for the overall speed of the computer.

In general, microprocessors handle three types of calculations:
1. Data manipulation
2. Logical comparisons
3. Mathematical calculations

MULTITASKING
basically, multitasking is performing two tasks on your computer simultaneously. For example, if you are working on a spreadsheet and open a web browser to check some information, you are multitasking. The ability to multitask is determined by the operating system, and enable you to go from one task or application to another without losing data (although there are certain limits to multitasking capabilities). Today's popular operating systems (Windows 98, Windows NT or Windows Me for example) are capable of multitasking.

MOTHERBOARD
This is your PC's main circuitboard, and is generally referred to as the "heart" of the computer. The CPU, BIOS, main memory, expansion cards and drives all connect to the motherboard. Motherboards are available in two common sizes: ATX and MicroATX. For details, refer to the Motherboard section of the TigerDirect.com Online University.

OEM
OEM is an abbreviation for Original Equipment Manufacturer and refers to a situation when a company purchases components from another company to use in a product that they build and market under their own name. For example, many CD drive manufacturers buy the internal components from Philips or Mitsubishi, then package the final CD drive with their brand name.

ON DIE
Slang term for "located on the chip." This term is often used when referring to L2 cache, which may or may not be located on the chip.

OPERATING SYSTEM or OS
The system's operating system is the program that manages all the activities of the other programs in your PC. The operationg system determines whether or not you can multi-task (open more than one application at a time), among other things. Windows 98, UNIX and IBM's OS/2 are examples of operating systems.

OVERCLOCKING
Overclocking is the practice of adjusting your computer settings so the CPU will run faster that the speed recommended by the manufacturer. Overclocking is not recommended and may void your CPU's warranty. However, many experienced PC users overclock for certain tasks.

PCI or Peripheral Component Interface
This is a type of bus (or data pathway) in a computer. Most of today's motherboards have five PCI slots (some may have fewer) into which expansion cards (i.e.: sound cards, video cards) can be plugged. The PCI bus has a high bandwidth, and replaces the older ISA bus.

PDA or Personal Digital Assistant
A Personal Digital Assistant is a small, portable device that includes a microprocessor and is used to perform computing tasks. PDAs are also referred to as "handheld" computers, and typically include addressbook, to-do list, notepad and other applications. Many include touch-screen data input and/or keyboards. Later model PDAs may include (or may be upgraded to include) wireless technology that gives them the ability to access the Internet and e-mail. Palm's Pilot series and Visor's Handspring are examples of PDAs.

PIPELINING
This is a technique used in many microprocessors to improve performance. A microprocessor utilizing pipelining will begin executing a second instruction BEFORE it has completed the first. This is done by splitting commands into segments; each segment can execute its operation at the same time as the other segments. More advanced pipeline technology can handle more segments.

PLUG-AND-PLAY or PnP
Plug-and-Play is a technology that was developed by Microsoft for its Windows 95 operating system (and is still in use) allowing users to easily add hardware to their systems. With Plug-and-Play, a PC user can simply "plug" a compatible device into the motherboard without the need for configuration.

RAID
An acronym for Redundant Array of Independent Disks. RAID configurations are typically used in servers. Increasingly, however, PC users are taking advantage of RAID technology. A RAID configuration consists of two or more hard drives (some larger RAID configurations have dozens of drives) recognized by the operating system as a single hard drive. When a user "saves" data, it is saved TO ALL HARD DRIVES. This automatically creates a backup of the data. Data can be read from both (or many) drives simultaneously, delivering a drastic increase in performance. This is a basic RAID configuration, however, there are many types of RAID configurations possible.

RAM or Random Access Memory
This is the main memory in a personal computer. Data and applications that are in a PC are loaded from the hard drive to the RAM so they may be accessed quickly by the CPU. The system's bus is the direct pathway between the RAM and the CPU. However, when data is "saved," it is written directly to the hard drive, and not to the RAM. This is because when the computer is turned off, all information stored in the RAM is discarded.

RAMDAC
This is Random Access Memory Digital-To-Analog Converter. The RAMDAC chip is used to convert digital information to analog information, so that the monitor can display it.

RDRAM
A new type of memory (developed by Rambus Corp.,) that is significantly faster than SDRAM (the current main memory standard). RDRAM is also faster that the emerging DDR SDRAM. Motherboards that support the Intel Pentium 4 processor series requie RDRAM.

REFRESH RATE
This refers to the number of times per second that the image on a monitor is re-cast. Typically, it is about 80 times per second, almost inperceptable by the human eye. Older, lower-resolution monitors have a slight "flicker" under 80Hz. Today, monitors at or about 80Hz are virtually flicker-free.

REMOVABLE STORAGE
Removable storage refers to a device which stores data on media that is not "fixed." While a hard drive is a fixed disk storage device, CD-RW drives and Zip drives are examples of removable storage devices. In the case of a CD-RW, data can be recorded to the CD disk, then removed later.

RESOLUTION
Resolution is the number of pixels in a given area. The more pixels included in a specific area, the sharper and more detailed the image will be. Of course, the higher the resolution of an image, the more memory that will be required to display it.

SCSI
SCSI or Small Computer System Interface is used to connect peripheral devices such as drives or video devices to a computer. While the EIDE interface format is common in mainstream computers (mainly because of its low cost), SCSI is utilized by more savvy users who need to connect a number of peripheral devices to their computers. SCSI is faster and more expensive than EIDE.

SDR
Single Data Rate (SDR) refers to the transfer of data on the "falling edge" of the clock cycle, as opposed to DDR (Double Data Rate), which transfers data on both the rising and falling edges of the clock cycle, resulting in twice the data throughput.

SDRAM
SDRAM is the current standard of main memory in personal computers. SDRAM (Synchronized DRAM) memory is synchonized with the CPU's optimum clock speed, which delivers best-possible performance. DRAM (Dynamic Random Access Memory), is an older standard which is not synchonized with the CPU clock speed.

SVGA
Current PC monitors are SVGA (Super Video Graphics Array). SVGA refers to the monitor's ability to can display up to 16+ million colors. The resolution of the image is dependent on the size of the monitor.

SERVER
The term "server" is often used to describe either a computer program that is designed to assist other programs that may be in the computer, or to describe the computer that houses the server program. A server is typically a computer linked to a network (or the Internet) that stores data and programs and distributes information to users on the network.

SLOT 1
A connection format used to connect an Intel CPU to a motherboard. The "Slot 1" is actually designed into the motherboard so the CPU can be easily---and correctly---inserted into the socket on the motherboard. Most of Intel's Pentium III and Celeron CPUs use the Socket 370 connection format, also known as FC-PGA (Flip-chip grid array).

SLOT A
A slot in a motherboard designed to connect AMD CPUs to motherboards. However, many of AMD's newer processors use the Socket A connection format, rather than the Slot A.

SOCKET 370
An Intel designed socket in a motherboard, into which an Intel CPU can be connected.

SOFTMENU
A type of BIOS (Basic Input/Output System) that allows a PC user to set the system bus speed electronically, rather than manually, with jumpers or dip switches.

SYSTEM BUS
Alson referred to as the Front Side Bus (FSB), the system bus is the data pathway which connects the CPU and the PC's main memory (RAM). The CPU and main memory exchange information constantly over the FSB to complete tasks. The Front Side Bus is the most important bus in the PC.

UNIX
An operating system, typically used on workstations.

USB or Universal Serial Bus
A format for connecting devices to a computer which allows full "Plug-and-Play" connectivity, without any configuration or even requiring the PC to be restarted. Newer computers include USB ports, and many new printers, scanners, keyboards, etc. are USB-compatible. USB is technically a bus, or path on the motherboard along which data travels.

NOTE: The USB format requires that both the PC and the device must be USB-capable.

VESA
VESA (Video Electronics Standards Association) is a non-profit, international organization established in 1989 to create industry-wide standards with regard to interfaces for PCs, workstations and other computing systems.

VIDEO CARD
A video card plugs into your motherboard and enables the computer to display images on your monitor. Many motherboards have video capabilities built onto them, eliminating the need for a video card. Without a video card connected to the motherboard or built onto it, you will not be able to display anything on your monitor. Video cards are currently available in 2D and 2D/3D models. Video cards will plug into either a PCI slot or an AGP slot on the motherboard.

X86
Today's personal computing microprocessors are based on the X86 architecture, developed in the mid-1970s by Intel. In 1978, the first-generation of microprocessors came to market based on the 8086 processor. Today's 7th generation processors are far more powerful and complex, yet they link back to the original core architecture as the original 8086, which has come to be referred to as the "X86."