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
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
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
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).