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Glossary
AC
(Alternating Current) The common form of electricity from power plant to home/office. Its direction is reversed 60 times per second in the U.S.; 50 times in Europe. Contrast with DC.
AE
Applications Engineer.
AFS
Andrew File System.
AI
Artificial Intelligence.
ALU
Arithmetic-Logic Unit.
AM
Amplitude Modulated.
AMD
(Advanced Micro Devices, Inc.) A manufacturer of x86-compatible CPUs. AMD has become a competitor to Intel and its chips are used by many PC makers, including Compaq. Chips with the Am486, K5, K6 and K7 Athlon CPU's are made by AMD.
AMI
American Megatrends Inc.
ANSI
American National Standards Institute.
ASIC
Application Specific Integrated Circuit.
ASCII
American Standard Code for Information Interchange. Pronounced "ask-ee." A binary code for text as well as communications and printer control. It is used for most communications and is in the built-in character code in most minicomputers and all personal computers.
ASPI
(Advanced SCSI Programming Interface) An interface from Adaptec, Inc., that provides a common language between drivers and SCSI host adapters (Adaptec company website www.adaptec.com).
AT
Advanced Technology.
ATA
AT bus Attachment.
ATAPI
(AT Attachment Packet Interface). The interface specification for IDE drives. ATAPI defines the specification for CD-ROMs and tape drives.
ATM
Asynchronous Transfer Mode.
ATDM
Asynchronous Time Division Multiplexing.
AUI
Attached Unit Interface.
BCD
Binary Coded Decimal.
Benchmark
A test used to measure software or hardware performance.
BIOS (Basic Input/Output System)
Predefined procedures that support the transfer of information between the computer's hardware, such as memory, hard disks and the monitor. On personal computers the BIOS ("ROM BIOS") is built into the machine's read-only memory.
BiCMOS
Bipolar Complementary Metal-Oxide Semiconductor.
BNC
(British Naval Connector) A commonly used connector for coaxial cable. The plug looks like a tiny tin can with the lid off and two short pins sticking out on the upper edge on opposite sides. After insertion, the plug is turned, tightening the pins in the socket.
Bus
The set of hardware lines that connects different parts of the computer (such as the microprocessor, input/output ports, and memory) and over which data is transferred.
CD-ROM
(Compact Disc Read Only Memory) A compact disc format used to hold text, graphics and hi-fi stereo sound. It's like an audio CD, but uses a different track format for data. The audio CD player cannot play CD-ROMs, but CD-ROM players usually play audio CDs and have output jacks for a headphone or amplified speakers.
CD-ROMs hold in excess of 650MB of data, which is equivalent to about 250,000 pages of text or 20,000 medium-resolution images.
A CD-ROM drive (player, reader) connects to a controller card, which is plugged into one of the computer's expansion slots. Earlier drives used a proprietary interface and came with their own card, requiring a free expansion slot in the computer. Today, most CD-ROMs use the SCSI interface and can be daisy chained to an existing SCSI controller. Increasingly, CD-ROM drives are built with the IDE interface, which allows them to connect to the same Enhanced IDE controller that the hard and floppy disks are attached to.
Earlier CD-ROM drives transferred data at 150KB per second. Double, triple and quad-speed drives provide 2x, 3x and 4x the 150KB transfer rate. 40x speed drives increase transfer to 6MB/second. For full-motion video, at least 8x speed is required. Access times run from a slow half second to under 200 milliseconds. Audio and data reside on separate tracks and cannot be heard and viewed together on earlier drives that are not CD-ROM XA compliant. Unlike other optical disks, CD-ROMs, as well as audio CDs, use a spiral recording track just like the "ancient" phonograph record. See CD-ROM XA, CD-I and DVI.
CMOS (Complimentary Metal Oxide Semiconductor)
A battery-powered chip in 80286 (and more advanced) computers that preserves basic data about the system's hardware. Information such as the number and types of disks, amount of RAM, and keyboard type is stored in a CMOS chip. This information appears on your computer's "setup screen" which can be displayed during startup.
CPU (central processing unit)
The portion of a computer that performs computations, executes instructions and transfers information between all parts of the computer. Microcomputers contain single-chip central processing units, or microprocessors.
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