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Appendix D - Glossary
162
Conventional memory
The first 640 KB of system memory. Operating systems and
application programs can directly access this memory without
using memory-management software.
Disk
The device used by the computer to store and retrieve
information.
Disk
can refer to a floppy disk, hard disk, or CD-
ROM disk.
Disk cache
A software device that accumulates copies of recently used
disk sectors in RAM. The application program can then read
these copies without accessing the disk. This, in turn, speeds
up the performance of the application.
A cache is a buffer for transferring disk sectors in and out of
RAM. Data stored in a disk cache is a copy of data already
stored on the physical disk.
DMA (Direct Memory Access)
A method of transferring data from a device to memory
without having the data pass through the microprocessor.
Using DMA can speed up system performance.
DPMS
Display Power Management Signalling. Displays or monitors
that comply with this can be managed by the Power
Management features found in the system setup.
Floppy disk
A removable disk, also called
floppy
or
diskette
.
Hard drive
Also called
fixed
disk. A hard drive is connected to the
computer and can be installed or removed. Data written to a
hard drive remains until it is overwritten or corrupted.
The 2.5-inch hard drive in your computer was designed for
use in a notebook computer. Because hard drives in
notebook computers are smaller than those in desktop
computers, their maximum storage capacity may be less than
that of desktop hard drives. However, because of their
smaller size, the drives handle shock and vibration better
than larger drives, which is important for a notebook
computer.
I/O (Input/output)
Refers to peripheral devices, such as printers, that are
addressed through an I/O address.
I/O address
I/O stands for input/output. Peripheral devices, such as
printers, are addressed through the I/O port address.
IRQ (Interrupt Request Line)
The IRQ is a hardware line that a device uses to signal the
microprocessor when the device needs the microprocessor’s
services. The number of IRQs is limited by industry
standards.
LCD (Liquid-Crystal Display)
The LCD screen on your computer differs from the display
screen of a desktop monitor. Most desktop monitors use CRT
(cathode-ray tube) displays, which work by moving an
electron beam across phosphor dots on the back of the
screen. The phosphor dots light up to show the image. LCDs
use a liquid-crystal solution between two sheets of polarizing
material. Electric current passing through the liquid aligns the
crystals so that light can or cannot pass through them,
creating an image.