Specifications

42
Appendix A Glossary
keylock Physical locking mechanism to prevent
internal access to the system unit or peripherals.
kibi A multiplier indicating 1,024 of some unit.
Abbreviated as Ki. See also gibi.
kilo A multiplier indicating one thousand
(1,000) of some unit. Abbreviated as k or K. When
used to indicate a number of bytes of memory stor-
age, the multiplier definition changes to 1,024. One
kilobit, for example, equals 1,000 bits, whereas one
kilobyte equals 1,024 bytes.
kilobyte (KB) A unit of information storage
equal to 1,000 bytes (decimal) or 1,024 bytes
(binary). Binary KB are now called kibibytes. See
also kibi.
kludge An inelegant but workable solution for a
software or hardware problem.
KVM switch Short for keyboard-video-mouse
switch, it’s a device that permits a single keyboard,
display, and mouse to control two or more PCs or
servers.
L1 cache (level one) A first level processor
memory cache built into the CPU core of 486 and
later generation processors. See also cache and disk
cache.
L2 cache (level two) A second-level processor
memory cache, usually larger and sometimes slower
than L1. Originally external to (and running signif-
icantly slower than) the processor, L2 was first inte-
grated into the processor package in the Pentium
Pro (November 1995), and later directly into the
CPU die in the Mendocino core versions of the
Celeron processor (August 1998). Since then virtu-
ally all new processors have included on-die L2
cache running at the full core speed of the pro-
cessor. See also SEC, cache, and disk cache.
L3 cache (level three) A third-level processor
memory cache rarely used in PC processors. See
also cache and disk cache.
LAN Local area network; a network contained
within a building. Both home and office networks
are considered LANs. Ethernet, Fast Ethernet,
Gigabit Ethernet, and Wireless Ethernet are used
in office LANs, whereas home LANs might use
Ethernet, Fast Ethernet, HomePNA, HomeRF, or
Wi-Fi Wireless Ethernet.
landing zone An unused track on a disk surface
on which the read/write heads can land when
power is shut off. The place a parking program or a
drive with an autopark mechanism parks the heads.
LAPM (link-access procedure for modems)
An error-control protocol incorporated in CCITT
Recommendation V.42. Similar to the MNP and
HST protocols, it uses cyclic redundancy checking
(CRC) and retransmission of corrupted data (ARQ)
to ensure data reliability.
laptop computer A computer system smaller
than a briefcase but larger than a notebook that usu-
ally has a clamshell design in which the keyboard
and display are on separate halves of the system,
which are hinged together. These systems normally
run on battery power. Many vendors use the terms
notebook and laptop computer interchangeably.
large mode A translation scheme used by the
Award BIOS to translate the cylinder, head, and sec-
tor specifications of an IDE drive to those usable by
an enhanced BIOS. It doesn’t produce the same
translated values as LBA mode and is not recom-
mended because it is not supported by other BIOS
vendors.
large-scale integration See IC.
laser printer A type of printer that is a combi-
nation of an electrostatic copying machine and a
computer printer. The output data from the com-
puter is converted by an interface into a raster feed,
similar to the impulses a TV picture tube receives.
The impulses cause the laser beam to scan a small
drum that carries a positive electrical charge. Where
the laser hits, the drum is discharged. A toner,
which also carries a positive charge, is then applied
to the drum. This toner—a fine, black powder—
sticks to only the areas of the drum that have been
discharged electrically. As it rotates, the drum
deposits the toner on a negatively charged sheet of
paper. Another roller then heats and bonds the
toner to the page. See also LED printer.
latency 1) The amount of time required for a
disk drive to rotate half a revolution. Represents the
average amount of time to locate a specific sector
after the heads have arrived at a specific track.
Latency is part of the average access time for a
drive. 2) The initial setup time required for a mem-
ory transfer in DRAM to select the row and column
addresses for the memory to be read/written.
24_0789736977_AppA.qxd 8/15/07 9:24 AM Page 42