Specifications

Glossary
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control terminal mode and enable more complex
operations, including file transmission and saving
received files.
terminator Hardware or circuits that must be
attached to or enabled at both ends of an electrical
bus. A terminator prevents the reflection or echo-
ing of signals that reach the ends of the bus and
ensures that the correct impedance load is placed
on the driver circuits on the bus. Most commonly
used with the SCSI bus and Thin Ethernet.
TFT (thin-film transistor) The highest quality
and brightest LCD color display type. A method for
packaging one–four transistors per pixel within a
flexible material that is the same size and shape as
the LCD display, which enables the transistors for
each pixel to lie directly behind the liquid crystal
cells they control.
thick Ethernet See 10BASE-5.
thin Ethernet See 10BASE-2.
thin-film media Hard disk platters that have a
thin film (usually three-millionths of an inch) of
medium deposited on the aluminum substrate
through a sputtering or plating process.
Thinnet See 10BASE-2.
through-hole Chip carriers and sockets
equipped with leads that extend through holes in a
PC board.
throughput The amount of user data transmit-
ted per second without the overhead of protocol
information, such as start and stop bits or frame
headers and trailers.
thumb drive See keychain drive.
TIFF (tagged image file format) A way of
storing and exchanging digital image data.
Developed by Aldus Corporation, Microsoft
Corporation, and major scanner vendors to help
link scanned images with the popular desktop pub-
lishing applications. Supports three main types of
image data: black-and-white data, halftones or
dithered data, and grayscale data. Compressed TIFF
files are stored using lossless compression.
time code A frame-by-frame address code time
reference recorded on the spare track of a videotape
or inserted in the vertical blanking interval. The
time code is an eight-digit number encoding time
in hours, minutes, seconds, and video frames.
Token-Ring A type of local area network in
which the workstations relay a packet of data called
a token in a logical ring configuration. When a sta-
tion wants to transmit, it takes possession of the
token, attaches its data, and then frees the token
after the data has made a complete circuit of the
electrical ring. It transmits at speeds of 4, 16Mbps
or 100Mbps. Originally developed and supported
by IBM, support is now provided by Madge
Networks (www.madge.com).
toner The ultrafine, colored, plastic powder used
in laser printers, LED printers, and photocopiers to
produce the image on paper.
tower A personal computer that normally sits on
the floor and is mounted vertically rather than
horizontally.
TPI (tracks per inch) Used as a measurement
of magnetic track density. Standard 5 1/4" 360KB
floppy disks have a density of 48TPI, and the
1.2MB disks have a 96TPI density. All 3 1/2" disks
have a 135.4667TPI density, and hard disks can
have densities greater than 3,000TPI.
track One of the many concentric circles that
holds data on a disk surface. Consists of a single
line of magnetic flux changes and is divided into
some number of 512-byte sectors.
track density Expressed as tracks per inch (TPI);
defines how many tracks are recorded in 1" of space
measured radially from the center of the disk.
Sometimes also called radial density.
track-to-track seek time The time required for
read/write heads to move between adjacent tracks.
transistor A semiconductor device invented in
1947 at Bell Labs (released in 1948) that is used to
amplify a signal or open and close a circuit. In digi-
tal computers, it functions as an electronic switch.
It is reduced to microscopic size in modern digital
integrated circuits containing 100 million or more
individual transistors.
Transport Layer In the OSI reference model,
when more than one packet is in process at any
time, such as when a large file must be split into
multiple packets for transmission, this is the layer
Appendix A
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