System information

Glossary
g-13
Glossary
dialog box A pop-up window in the user interface with informational messages
or fields to be modified or completed with the required options.
D_ID See destination address.
digital transmission Information is converted to binary computer code (a series of 0s and
1s). The information is sent in this format and then converted into its
original format when it reaches its destination.
direct access storage
device
DASD. (1) Generic classification for a storage peripheral that can
respond directly to random requests for information. Usually refers
to a disk drive. (2) A storage device that provides direct access to
data, and in which access time is independent of data location.
direct current DC. Electric current that continuously flows in one direction (D).
Contrast with
alternating current. See volts direct current. See also
alternating current/direct current converter.
director An intelligent, highly-available, FC switch providing any-to-any port
connectivity between nodes (end devices) on a switched fabric. The
director sends data transmissions (data frames) between nodes in
accordance with the address information present in the frame
headers of those transmissions.
disaster recovery A program that is designed to help companies get back to normal
activities after a catastrophic interruption. Through failover to a
parallel system, or by restoration of the failed system, disaster
recovery restores the system to its normal operating mode.
disk controller The chip or circuit that controls the transfer of data between the disk
and buffer. See also
disk drive controller; interface controller.
disk drive controller The hard disk drive controller electronics that include the disk
controller and the interface controller. See also
disk controller;
interface controller.
diskette A thin magnetic disk enclosed in a plastic jacket, which is removable
from a computer and is used to store and transport data (D).
diskette drive The hardware mechanism by which a computer reads data from and
writes data to removable diskettes (D).
disk mirroring The duplication of disks and controllers so that two access paths exist
in case a failure occurs on one of them.