AGP (Accelerated Graphics Port) Intel's AGP specification describes a high-speed bus that allows a computer's graphics controller to talk directly to portions of main system memory, bypassing the slower PCI bus. Older desktops supported AGP 1X (264-MBps transfer rate) and AGP 2X (528 MBps), but newer systems support AGP 4X (1.056 GBps).

ATA (AT Attachment) This is a standard for connecting mass-storage devices such as hard drives, CD-ROM drives, and tape drives to a PC. Also known as IDE.

Bus A bus is a collection of electrical lines that carry data (one bit per line), power, or a combination and to which multiple devices, such as expansion cards, can connect.

Cable modem This is a communications device that transmits data over cable-TV lines at speeds of 1 Mbps to 10 Mbps and connects to your computer via Ethernet.

Cache A cache is high-speed memory that normally resides in the processor and holds the most recently used data for quick retrieval. Most processors have Level 1 (primary) and Level 2 (secondary) caches. Level 3 is coming soon.

CD-ROM These optical discs store prerecorded digital data in read-only form and are most often used by publishers for distributing programs, data, music, or graphics.

CD-R CD-R media are optical discs that can be recorded on by the end user but cannot be erased.

CD-RW Optical discs of this type can be recorded on and erased numerous times.

Chip set A chip set is a group (generally) of separate integrated circuits that control the flow of information among the components on the motherboard.

CPU (central processing unit) This integrated circuit is the brains of a modern computer The CPU contains the arithmetic and logic hardware that does the bulk of the information processing.

DIMM (Dual Inline Memory Module) A small circuit board with memory chips mounted on both sides. The bottom edge of a DIMM has electrical contacts printed on it and plugs into a special connector that is usually on the motherboard.

DMA (Direct Memory Access) This is a method of moving blocks of data between a storage device and memory without utilizing the CPU. (See Ultra DMA.)

DRAM (Dynamic Random Access Memory) The term dynamic in this acronym refers to the need to constantly refresh the contents of this type of memory in order to retain information.

DVD These optical discs are capable of holding more data than a CD, in part because they use both sides of the media (CDs only use one side).

DVD-RAM This type of DVD can be recorded to, erased, and re-written many times, and can hold up to 17GB.

DVD-ROM These discs are read-only and can hold up to 17GB of prerecorded information. They are used for distribution of large programs, movies, music, data, and more.

IDE (Integrated Device Electronics) IDE makes the controlling circuitry for mass-storage devices part of the devices themselves. This technology is the standard way of connecting hard drives, CD-ROM drives, and tape drives to a system.

IEEE 1394 (Institute for Electrical and Electronic Engineering standard number 1394) Otherwise known as FireWire, this is a high-speed serial bus used for connecting peripheral devices, such as digital camcorders.

Memory The processor stores the information it needs in these microchips, which are commonly referred to as RAM. Other devices, especially video cards, often have memory of their own.

Modem A modem converts digital signals from a computer to analog signals that can be transmitted over a telephone line and reverses the process for receiving information over the telephone line.

Motherboard This is the computer's main circuit board, on which the processor and system memory reside, as well as the chip sets that control information flow and the circuitry that connect components to the processor and each other.

RAID (Redundant Array of Inexpensive Drives) The acronym refers to a collection of hard drives attached to a special controller that, among other abilities, can improve performance by sharing data across multiple drives (one such configuration is known as RAID 0) and improve reliability by having some drives mirror (fully duplicate) others in real time.

RAM (random access memory) RAM packs millions of data-storing electrical circuits onto a small chip. Devices can write to and read from these storage locations, and the CPU uses this memory to hold programs and data.

ROM (read-only memory) Memory containing information that can be read but not modified.

SCSI (Small Computer System Interface) SCSI is a standard for a high-speed bus used to connect multiple peripherals such as hard drives, printers, and CD-ROM drives.

SIMM (Single Inline Memory Module) SIMM is almost identical to DIMM, but mounts the memory on only one side of a small circuit board.

SMART Drive (Self-Monitoring Analysis and Reporting Technology) Hard drives with SMART contain logic circuits that monitor the drives' health, providing a warning system that predicts potential drive failure.

SRAM (Static RAM) Memory that, unlike DRAM, doesn't require its contents to be constantly refreshed in order to retain information.

System bus The system bus interconnects the components on the motherboard, including the CPU.

Ultra DMA Also known as Ultra ATA, this improves on the original DMA protocol by enabling burst mode data transfer rates of 33.3 MBps. This is twice as fast as the previous standard.

USB (Universal Serial Bus) USB is a popular low-speed serial connection method for linking many types of peripherals to computer systems. USB is quickly replacing serial, parallel, ps/2, and even, on some systems, monitor ports. The current standard, USB 1.0, can transfer data at up to 12 Mbps and connect as many as 127 devices. Peripherals can be plugged in and unplugged without shutting down the system. More and more devices incorporate USB ports-digital cameras, displays (especially flat-panel), keyboards, joysticks, mice, modems-and the list keeps growing. A faster standard, USB 2.0, is in the works.