daemon --
A background process that performs a regular routine or provides
a service without human intervention. A daemon might be started as
a response to some event, or it can be executed at regular intervals.
One of the most important daemons on the system is
cron, which regularly runs other programs.
database --
A collection of information, or data, organized in a specific
order and format so that the information can be retrieved, stored,
and manipulated by an application.
datagram --
Transmission unit at the IP level.
A unit of data transferred between two users of the
connectionless-mode service.
See also
packet.
datagram transport --
(programming)
See
connectionless transport.
data integration --
The ability to transfer information between different programs
and applications;
for example, the ability to copy data from a spreadsheet into
a report being created with a word processing program.
See also
Clipboard
and
file type.
data integrity --
The consistency between stored data that has not been exposed to
alteration or destruction (either accidental or malicious) and the
source data.
data structure --
(programming)
The memory storage area that holds data types, such as integers
and strings, or an array of integers.
The data structures associated with drivers are used as buffers
for holding data being moved between user data space and the device,
as flags for indicating error device status,
as pointers to link buffers together, and so on.
data symbol --
(programming)
A data symbol names a variable that might or might not
be initialized. Normally, these variables reside in
read/write memory during execution.
See also
text symbol.
data transfer --
(programming)
The phase in
connection-mode
or connectionless-mode that
supports the transfer of data between two transport users.
DCU --
See
Device Configuration Utility (DCU).
DDI --
Device Driver Interface.
debugging --
(programming)
Debugging is the process of locating
and correcting errors in executable programs.
decode --
For SNMP, to convert a string of octets into an
ASN.1
instance of a data type.
default --
The standard configuration or values for a screen, program, or field.
For example, the default Desktop is displayed the very first
time you start the Desktop, before you have made any changes.
demand paging --
(programming)
A memory management system that allows unused portions of a program
to be stored temporarily on disk to make room for urgently needed information
in main memory.
With demand paging, the virtual size of a process can exceed the
amount of physical memory available in a system.
descriptor --
(programming)
An element of the Form and Menu Language Interface (FMLI
that defines some aspect
of the look (appearance or location of an element of your application),
or feel (an action to take in response to user input).
A descriptor is coded in the format dname = value,
where dname is one of the set of Form and Menu Language
descriptors and value is, or generates, an expression of
a type appropriate for the particular descriptor.
Each Form and Menu Language descriptor is only meaningful in
a particular context (for example, a menu frame or a form frame).
deserializing --
(programming)
Converting data from XDR format to a machine-specific
representation.
device --
Peripheral hardware attached to the computer such as a
printer, modem, disk or tape drive, or terminal.
A device is controlled by a
device driver
which is linked into the
kernel.
device activation --
The means by which a
device
is accessed.
A device can be accessed only by an activated
Device Special File (DSF)
(DSF) that maps to it.
device allocation --
Device access by any one of several kernel mechanisms that
support access to devices.
The permission, usage, and protection strategies for accessing a device
depend on the specific device,
its intended use, and the programs that do the allocation.
Device Configuration Utility (DCU) --
A software program that allows you to review and change the hardware
configuration of your system, including assigning device drivers
to hardware controllers and changing device driver parameters, such
as the interrupt vector.
device disabled state --
The state in which a device is not accessible.
The only operations allowed on a device in this state
are the transitions to
device setup state
or
device enabled state.
device driver --
A software interface between the system and a hardware device.
Device drivers are represented by files in the filesystem, usually
contained in the /dev directory.
device enabled state --
The state in which a device is fully operational
which cannot be changed even by a privileged process.
From the enabled state, a device can be taken to the
device setup state
or the
device disabled state.
driver entry points --
(programming)
Driver routines that provide an interface
between the
kernel
and the
device driver.
device number --
(programming)
The value used by the operating system to name a
device.
The device number contains the major number and the minor number.
device readiness state --
One of three states,
device disabled state,
device setup state,
or
device enabled state,
that each configured device
must be in. These states are used to assure proper allocation
by device allocation mechanisms.
A device can make the transition from any state
to either of the others, but some restrictions apply.
device setup state --
The state used by a
device allocation
program to prepare a device for use.
Device Special File (DSF) --
The mechanism through which processes address devices.
The DSF has the structure of a regular file
but it lacks a data area and has only an inode.
Data in the inode indicates a path through various kernel
tables that eventually maps to a single, logical device.
Although this logical device is conceptually a single data object,
more than one DSF can map onto a single device.
See also
device allocation.
dev_t --
(programming)
The C programming language data type declaration that is used to store
the driver major and the minor device numbers.
diagnostic --
A software routine for testing, identifying, and isolating
a hardware error. A message is generated
to notify the tester of the results.
dialog box --
A pop-up window that contains options or instructions. By
responding, you carry on a dialog with a program.
dimmed --
1. An object that is not available for selection.
2. (programming) A visual effect on an object.
A control, such as a
button,
is dimmed if its visible
manifestation represents the state of just one of several
objects that are in inconsistent states.
When such a control is manipulated (for example, by clicking <SELECT>
over the button), it is no longer dimmed because the
manipulation sets the state for all the objects.
disk --
A magnetic data storage device consisting of several round plates
similar to phonograph records. Disks store large amounts of data
and allow quick access to any piece of data.
directory --
Where the UNIX system stores
files.
Directories in the UNIX system are arranged in an
upside-down tree hierarchy, with the
root
(/) directory at the top. All other directories
branch out from the
root
directory. The UNIX system implements directories as
normal files that store the names of the files
within them.
directory icons --
The icons that represent directories.
To open a
directory window,
double-click on the directory icon with mouse button 1.
The directory window displays the files and any subdirectories
contained in the directory.
directory window --
The window that displays the files and any subdirectories
contained in a directory.
Open a directory and display its directory window by
double-clicking on the directory icon with mouse button 1.
diskette --
A thin data storage disk permanently enclosed in
a protective jacket, usually either 5¼" or 3½" in size.
Diskettes are transportable between machines fitted with the
appropriate disk drives. Also known as a floppy disk.
dispersion --
A measure, in seconds, of how scattered the time offsets have
been from a given time server.
display width --
(programming)
Display width is the width in screen columns required to display
the characters of a particular code set.
Display width is defined in the character class table.
display windows --
Defined areas of the screen that display specific information,
such as file listings or a menu of available applications.
You can customize window size, location, and content.
distributed interrupts --
Device interrupts that can be serviced by any CPU in the
system.
DLPI --
Data Link Provider Interface.
document --
A collection of text, edited and formatted with word processing
commands, located in a file.
domain --
Information used for mail delivery that describes
the site where a computer is located
and generally includes the machine (host) name, a department
(optionally), and the site's organization or country.
domain name server --
A computer that maintains a database
that can provide information about host
names and addresses within a domain.
See also
name server.
Domain Name Service (DNS) --
A service available with TCP/IP that lets a group of systems (defined as a
domain) share the system names and addresses list for many systems. DNS
saves the overhead of having every system maintain its own list of systems.
domain tables --
Tables that are used to match a short host name to its
fully qualified host name.
Domain tables can be used to convey information to MMDF
about how machines are connected
and about any special domain routing considerations.
DOS --
A type of operating system, most commonly used on small personal
computers.
It might sometimes be called MS-DOS®. See also
DOS command line.
DOS command line --
A line in a DOS window, on which you can enter commands
to communicate with the DOS operating system. See also
DOS.
DOS drive --
The hardware associated with DOS
diskettes,
fixed disks. or CD-ROM drives.
DOS drives are named with letters followed by a colon.
By convention, diskette drives are usually designated A: and
B:, and a local fixed disk is designated C:.
DOS executable files --
A file that contains a DOS program or command.
The program or command is executed when you enter
the name of the file on a command line.
DOS requires names of executable files to end with one of the
three-letter extensions .BAT, .COM,
or .EXE (for example AUTOEXEC.BAT
and COMMAND.COM.). See also
DOS
and
DOS command line.
dot file --
A UNIX file that configures some aspect of the Desktop,
related programs, or your computer environment. Dot files
are so called because their filenames start with a period
or ``dot.'' They are usually created automatically and
reside in each user's home directory. You can choose
whether or not you want to display dot files in a directory
window.
double-click --
To click a mouse button twice in rapid succession. When
the mouse button is not specified, double-click refers to
mouse button 1. See also
click.
downstream --
(programming)
In a stream, the direction from stream head to driver.
draft mail message --
An e-mail message that is in the process of being composed.
drag --
To press and hold a mouse button while moving the mouse,
which moves a selected object on the screen. If you select
multiple icons, dragging one of them performs the same
action on all of them. See also
drop.
drag area --
(programming)
In a Scrollbar widget, the drag area is the center portion of the
elevator that is moved by the mouse.
drag box --
(programming)
In a Slider widget, the drag box is the portion of the slider
that is moved by the mouse.
drift --
A measure, in Hertz, of how quickly the skew of a
clock is changing. See also
skew.
driver --
(programming)
1. The set of routines and data structures installed in the
kernel that provide an interface between the kernel and a device.
2. In a stream, the driver provides the interface between
peripheral hardware and the stream.
A driver can also be a pseudo-driver,
such as a multiplexor or log driver,
which is not associated with a hardware device.
drop --
To drag an icon on top of another and release the mouse button.
You drop one icon on another to perform certain tasks,
such as starting the text editor or sending a file to a printer.
This can also be called ``direct'' manipulation.
data terminal ready (DTR) --
The signal that a terminal device sends to a host
computer to indicate that a terminal is ready to receive data.
dumb terminal --
A display terminal that has no processing power. All processing is done by the
computer to which it is connected. You cannot run the desktop from
a dumb terminal, though you can log in and work from the
command line.
dynamically loadable drivers --
Special device drivers that can be loaded into the operating system
before it completes the boot procedure.
dynamic frame --
(programming)
A frame whose contents are determined at run-time.
dynamic linking --
(programming)
Dynamic linking refers to the process in which
external references in a program are linked with
their definitions when the program is executed.