daisy chain -
A method of device interconnection
for determining interrupt priority by connecting the interrupt sources serially.
data segment -
A nonexecutable
section of a program module; that is, a section of a program that contains
data definitions.
data structure -
The
syntactic structure of symbolic expressions and their storage-allocation
characteristics. (T)
data transfer -
The
movement of data from one object to another by way of the clipboard or by
direct manipulation.
DBCS -
Double-byte
character set.
DDE -
deadlock -
(1)
Unresolved contention for the use of a resource. (2) An error condition
in which processing cannot continue because each of two elements of the
process is waiting for an action by, or a response from, the other. (3)
An impasse that occurs when multiple processes are waiting for the availability
of a resource that will not become available because it is being held by
another process that is in a similar wait state.
debug
-
To detect, diagnose, and eliminate errors in
programs. (T)
decipoint -
In
printing, one tenth of a point. There are 72 points in an inch.
default
procedure -
A function provided by the Presentation
Manager Interface that may be used to process standard messages from dialogs
or windows.
default value -
A
value assumed when no value has been specified. Synonymous with assumed
value. For example, in the graphics programming interface, the default line-type
is 'solid'.
definition list -
A
type of list that pairs a term and its description.
delta
-
An application-defined threshold, or number
of container items, from either end of the list.
descendant
-
descriptive
text -
Text used in addition to a field prompt
to give more information about a field.
Deselect
all -
A choice that cancels the selection of
all of the objects that have been selected in that window.
Desktop
Manager -
In the Presentation Manager, a window
that displays a list of groups of programs, each of which can be started
or stopped.
desktop window -
The
window, corresponding to the physical device, against which all other types
of windows are established.
detached process
-
A background process that runs independent
of the parent process.
detent -
A
point on a slider that represents an exact value to which a user can move
the slider arm.
device context -
A
logical description of a data destination such as memory, metafile, display,
printer, or plotter. See also direct device context, information
device context, memory device context, metafile device context,
queued device context, and screen device context.
device
driver -
A file that contains the code needed
to attach and use a device such as a display, printer, or plotter.
device
space -
(1) Coordinate space in which graphics
are assembled after all GPI transformations have been applied. Device space
is defined in device-specific units. (2) ( D of
C) In computer graphics, a space defined by the complete set of addressable
points of a display device. (A)
dialog
-
The interchange of information between a computer
and its user through a sequence of requests by the user and the presentation
of responses by the computer.
dialog box
-
In SAA Advanced Common User Access architecture,
a movable window, fixed in size, containing controls that a user uses to
provide information required by an application so that it can continue to
process a user request. See also message box, primary window, secondary
window. Also known as a pop-up window.
Dialog
Box Editor -
A WYSIWYG editor that creates
dialog boxes for communicating with the application user.
dialog
item -
A component (for example, a menu or a
button) of a dialog box. Dialog items are also used when creating dialog
templates.
dialog procedure -
A
dialog window that is controlled by a window procedure. It is responsible
for responding to all messages sent to the dialog window.
dialog
tag language -
A markup language used by the
DTL compiler to create dialog objects.
dialog
template -
The definition of a dialog box, which
contains details of its position, appearance, and window ID, and the window
ID of each of its child windows.
direct device
context -
A logical description of a data destination
that is a device other than the screen (for example, a printer or plotter),
and where the output is not to go through the spooler. Its purpose is to
satisfy queries. See also device context.
direct
manipulation -
The user's ability to interact
with an object by using the mouse, typically by dragging an object around
on the Desktop and dropping it on other objects.
direct
memory access (DMA) -
A technique for moving
data directly between main storage and peripheral equipment without requiring
processing of the data by the processing unit.(T)
directory
-
A type of file containing the names and controlling
information for other files or other directories.
display
point -
dithering
-
(1) The process used in color displays whereby
every other pel is set to one color, and the intermediate pels are set to
another. Together they produce the effect of a third color at normal viewing
distances. This process can only be used on solid areas of color; it does
not work, for example, on narrow lines. (2) (D of C ) In computer graphics,
a technique of interleaving dark and light pixels so that the resulting
image looks smoothly shaded when viewed from a distance.
DMA
-
DOS
Protect Mode Interface (DPMI) -
An interface
between protect mode and real mode programs.
double-byte
character set (DBCS) -
A set of characters in
which each character is represented by two bytes. Languages such
as Japanese, Chinese, and Korean, which contain more characters than can
be represented by 256 code points, require double-byte character sets. Since
each character requires two bytes, the entering, displaying, and printing
of DBCS characters requires hardware and software that can support DBCS.
doubleword -
A contiguous
sequence of bits or characters that comprises two computer words and is
capable of being addressed as a unit. (A)
DPMI
-
DOS Protect Mode Interface.
drag
-
In SAA Common User Access, to use a pointing
device to move an object; for example, clicking on a window border, and
dragging it to make the window larger.
dragging
-
(1) In computer graphics, moving an object
on the display screen as if it were attached to the pointer. (2) (D of C)
In computer graphics, moving one or more segments on a display surface by
translating. (I) (A)
drawing chain -
drop -
To
fix the position of an object that is being dragged, by releasing the select
button of the pointing device. See also drag.
DTL
-
dual-boot
function -
A feature of the OS/2 operating system
that allows the user to start DOS from within the operating system, or an
OS/2 session from within DOS.
duplex -
Pertaining
to communication in which data can be sent and received at the same time.
Synonymous with full duplex.
dynamic data
exchange (DDE) -
A message protocol used to communicate
between applications that share data. The protocol uses shared memory as
the means of exchanging data between applications.
dynamic
data formatting -
A formatting procedure that
enables you to incorporate text, bit maps or metafiles in an IPF window
at execution time.
dynamic link library -
A
collection of executable programming code and data that is bound to an application
at load time or run time, rather than during linking. The programming code
and data in a dynamic link library can be shared by several applications
simultaneously.
dynamic linking -
The
process of resolving external references in a program module at load time
or run time rather than during linking.
dynamic
segments -
Graphics segments drawn in exclusive-OR
mix mode so that they can be moved from one screen position to another without
affecting the rest of the displayed picture.
dynamic
storage -
(1) A device that stores data in a
manner that permits the data to move or vary with time such that the specified
data is not always available for recovery. (A) (2) A storage in which
the cells require repetitive application of control signals in order to
retain stored data. Such repetitive application of the control signals is
called a refresh operation. A dynamic storage may use static addressing
or sensing circuits. (A) (3) See also static storage.
dynamic
time slicing -
Varies the size of the time slice
depending on system load and paging activity.
dynamic-link
module -
A module that is linked
at load time or run time.
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