Specifications
68
Appendix A Glossary
system files Files with the system attribute.
Usually, the hidden files that are used to boot the
operating system. The MS-DOS and Windows 9x
system files include
IO.SYS and MSDOS.SYS; the IBM
DOS system files are
IBMBIO.COM and IBMDOS.COM.
System Management Mode (SMM) Circuitry
integrated into Intel processors that operates inde-
pendently to control the processor’s power use
based on its activity level. It enables the user to
specify time intervals after which the CPU will be
powered down partially or fully and also supports
the suspend/resume feature that enables instant
power-on and power-off.
T13 The T13 Technical Committee (www.t13.org)
is responsible for developing ATA and SATA
standards.
tape drive Any data storage drive that uses tape
as the storage medium.
tape library An array of tape drives that can be
partitioned into multiple logical libraries. Tape
libraries incorporate autoloaders. See also
autoloader.
target A device attached to a SCSI bus that
receives and processes commands sent from
another device (the initiator) on the SCSI bus. A
SCSI hard disk is an example of a target.
TCM (Trellis-coded modulation) An error-
detection and correction technique employed
by high-speed modems to enable higher-speed
transmissions that are more resistant to line
impairments.
TCO 1) Refers to the Swedish Confederation of
Professional Employees, which has set stringent
standards for devices that emit radiation. See also
MPR. 2) Total cost of ownership. The cost of using a
computer. It includes the cost of the hardware, soft-
ware, and upgrades as well as the cost of the in-
house staff and consultants who provide training
and technical support.
TCP (tape carrier package) A method of
packaging processors for use in portable systems
that reduces the size, power consumed, and heat
generated by the chip. A processor in the TCP form
factor is essentially a raw die encased in an over-
sized piece of polyamide film. The film is laminated
with copper foil that is etched to form the leads
that will connect the processor to the motherboard.
TCP port number Logical port numbers used
by TCP to communicate between computers—for
example, web browsing (http://) uses TCP port 80.
POP3 email uses TCP port 110. Some firewalls
require you to manually configure open TCP port
numbers to allow certain processes and programs
to work.
TCP/IP (Transmission Control
Protocol/Internet Protocol) A set of proto-
cols developed by the U.S. Department of Defense
(DoD) to link dissimilar computers across many
types of networks. This is the primary protocol
used by the Internet.
TEB Thin Electronics Bay is an SSI-developed
standard for rack-mounted servers.
Temporal Key Integrity Protocol (TKIP) A
technique for scrambling encryption keys and
changing the keys over time.
temporary backup A second copy of a work
file, usually having the extension
.BAK. Created by
application software so you easily can return to a
previous version of your work.
temporary file A file temporarily (and usually
invisibly) created by a program for its own use.
tera A multiplier indicating one trillion
(1,000,000,000,000) of some unit. Abbreviated as t
or T. A binary tera (now called a tebi) is
1,099,511,627,776.
terabyte (T) A unit of information storage equal
to 1,000,000,000,000 bytes.
terminal A device whose keyboard and display
are used for sending and receiving data over a com-
munications link. Differs from a microcomputer in
that it has no internal processing capabilities. Used
to enter data into or retrieve processed data from a
system or network.
terminal mode An operational mode required
for microcomputers to transmit data. In terminal
mode, the computer acts as though it were a stan-
dard terminal, such as a teletypewriter, rather than
a data processor. Keyboard entries go directly to the
modem, whether the entry is a modem command
or data to be transmitted over the phone lines.
Received data is output directly to the screen. The
more popular communications software products
24_0789736977_AppA.qxd 8/15/07 9:24 AM Page 68