Glossary 3
card-edge connector
On the bottom of an expansion card, the metal-contact sec-
tion that plugs into an expansion-card connector.
CCFT
Abbreviation for cold cathode fluorescent tube.
CD-ROM
Abbreviation for compact disc read-only memory.
CD-ROM drives use optical technology to read data from
compact discs. Compact discs are read-only storage
devices; you cannot write new data to a compact disc with
standard CD-ROM drives.
CGA
Abbreviation for color graphics adapter.
cm
Abbreviation for centimeter(s).
CMOS
Acronym for complementary metal-oxide semiconductor.
In computers, CMOS memory chips are often used for
NVRAM storage.
COM
n
The MS-DOS device names for the first through fourth
serial ports on your computer are COM1, COM2, COM3,
and COM4. MS-DOS supports up to four serial ports.
However, the default interrupt for COM1 and COM3 is
IRQ4, and the default interrupt for COM2 and COM4 is
IRQ3. Therefore, you must be careful when configuring
software that runs a serial device so that you don’t create
an interrupt conflict.
CON
The MS-DOS device name for the console, which includes
your computer’s keyboard and text displayed on the
screen.
config.sys
file
When you boot your computer, MS-DOS runs any com-
mands contained in the text file, config.sys (before running
any commands in the autoexec.bat file). A config.sys file is
not required to boot MS-DOS, but provides a convenient
place to run commands that are essential for setting up a
consistent computing environment—such as loading de-
vice drivers with a device= statement.
controller
A chip or expansion card that controls the transfer of data
between the microprocessor and a peripheral, such as a
disk drive or the keyboard.
conventional memory
The first 640 KB of RAM. Unless they are specially de-
signed, MS-DOS programs are limited to running in
conventional memory. See also EMM, expanded memory,
extended memory, HMA, memory manager, upper mem-
ory area, and XMM.
coprocessor
A coprocessor relieves the computer’s microprocessor of
specific processing tasks. A math coprocessor, for exam-
ple, handles numeric processing. A graphics coprocessor
handles video rendering. Intel486 DX
™
, IntelDX2
™
,
IntelDX4
™
, and Pentium
®
, and Pentium Pro micro-
processors include a built-in math coprocessor.
cpi
Abbreviation for characters per inch.
CPU
Abbreviation for central processing unit. See also
microprocessor.
cursor
In character-based MS-DOS programs, the cursor is usually
a block or an underscore (possibly blinking) that represents
the position at which the next character typed will appear.
Windows programs can design their own cursors—common
cursor symbols include the pointer arrow and the text-
insertion I-beam.
DAC
Acronym for digital-to-analog converter.
DAT
Acronym for digital audio tape.
dB
Abbreviation for decibel(s).
dBA
Abbreviation for adjusted decibel(s).
DC
Abbreviation for direct current.
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