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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 only at 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 results in greater speed.
BIOS (Basic Input/Output System): the program that resides in the ROM chip, which
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 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 the possibility of losing your data should the system
crash. Information 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).
Cache: a temporary storage area for data that will be needed often by an application.
Using a cache lowers data access times since the information is stored in SRAM instead
of slower DRAM. Note that the cache is also much smaller than your regular memory: a
typical cache size is 512KB, while you may have as much as 4GB of regular memory.