Appendix I: Glossary 

ACPI (Advanced Configuration and Power Interface): a power management 

specification that allows the operating system to control the amount of power distributed to 

the computer's devices. Devices not in use can be turned off, reducing unnecessary 

power expenditure. 

AGP (Accelerated Graphics Port): a PCI based interface which was designed 

specifically for demands of 3D graphics applications. The 32 bit AGP channel directly 

links the graphics controller to the main memory. While the channel runs at only 66 MHz, 

it supports data transmission during both the rising and falling ends of the clock cycle, 

yielding an effective speed of 133 MHz. 

ATAPI (AT Attachment Packet Interface): also known as IDE or ATA; a drive 

implementation that includes the disk controller on the device itself. It allows CD ROMs 

and tape drives to be configured as master or slave devices, just like HDDs. 

ATX: the form factor designed to replace the AT form factor. It improves on the AT design 

by rotating the board 90 degrees, so that the IDE connectors are closer to the drive bays, 

and the CPU is closer to the power supply and cooling fan. The keyboard, mouse, USB, 

serial, and parallel ports are built in. 

Bandwidth: refers to carrying capacity. The greater the bandwidth, the more data the bus, 

phone line, or other electrical path, can carry. Greater bandwidth, then, also results in 

greater speed. 

BBS (BIOS Boot Specification): is a feature within the BIOS that creates, prioritizes, and 

maintains a list of all Initial Program Load (IPL) devices, and then stores that list in 

NVRAM. IPL devices have the ability to load and execute an OS, as well as provide the 

ability to return to the BIOS if the OS load process fails for some reason. At that point, the 

next IPL device is called upon to attempt loading of the OS. 

BIOS (Basic Input/Output System): the program that resides in the ROM chip, and 

provides the basic instructions for controlling your computer's hardware. Both the 

operating system and application software use BIOS routines to ensure compatibility. 

Buffer: a portion of RAM, which is used to temporarily store data, usually from an 

application, though it is also used when printing, and in most keyboard drivers. The CPU 

can manipulate data in a buffer before copying it, all at once, to a disk drive. While this 

improves system performance     reading to or writing from a disk drive a single time is 

much faster than doing so repeatedly     there is also the possibility of losing your data 

should the system crash. Information stored in a buffer is temporarily stored, not 

permanently saved. 

Bus: a data pathway. The term is used especially to refer to the connection between the 

processor and system memory, and between the processor and PCI or ISA local buses. 

Bus mastering: allows peripheral devices and IDEs to access the system memory 

without going through the CPU (similar to DMA channels). 

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