أكاديميا - كولنز - معاجم الجيب العلمية - الكمبيوتر - انكليزي - فرنسي - عربي الحرف ٣_d

Academia - Collins - Scientific Pocket Dictionaries - Computer - English - French - Arabic Letter 3_ D

disk (or disc)
disque m

Disk. A flat circular plate covered with a magnetic material capable of storing data on concentric tracks. As the disc rotates, the read/write head moves from the edge to the center, selecting only the required tracks. Each track is divided into sectors. A coordinated program is used to place the tracks and sectors on a blank disc. Disks allow for fast direct access times compared to much slower serial tapes.

disk unit
unité f du disque

A disk unit is a peripheral device consisting of a disk drive and one or more read/write units. Disks can be fixed in place (hard disks). Disks for microcomputers that can be lifted from their place are called floppy disks or diskettes. When the disk is inside the unit, it can be accessed by the read/write head while it is rotating at high speed.

documentation
documentation

Documentation. Typically, it accompanies a computer program and gives instructions on how to use the package and what output to expect. It may also include a flowchart, a list of programs, a list of variables, and test procedures with sample data. Documentation is useful to the user of the program but is essential for making changes to the program.

document reader
lecteur m de documents

Document reader. A computer input device in which a machine reads (at high speed) the formats marked at specific locations. Examples include magnetic ink, optical character recognition, and mark sense cards.

DOS
DOS

Disk operating system

dot matrix printer
inprimante f par points

Dot matrix printer. A printer that forms characters on paper by printing a pattern of dots. The print head consists of a set of horizontal pins arranged one above the other in a row. When the head moves sideways, certain wires are pushed forward to form a column of dots on the paper. A number of similar columns form a character. Old matrix heads had seven pins, but they were unable to print character suffixes (such as the tail in g and y). Today, nine pins are used, but there are printers with 16, 18, and even 24 pins. A range of colors can be obtained by using a four-color ribbon, for example. Overprinting in different colors.

For example, a nine-wire dot matrix printer uses five dots for the lowercase letter plus two dots above the uppercase letter and two dots for the lowercase letters.

Improved printing is achieved by printing each letter twice, especially if the second print is slightly offset from the first, making the spaces between the dots less noticeable. This is often called near letter quality (NLQ).

Modern dot matrix printers can print up to 300 characters per second in draft mode (single print) and 60 characters per second in NLQ mode. They are preferred over daisywheel printers because they can print a variety of letter and graphic shapes and are quieter.

Although they are noisier and slower than laser printers, they are able to print carbon copies of paper because they work by impact.

double buffering
utilisation ƒ à double tampon

double buffering. Using two buffers in a computer so that one can be analyzed while the other is being filled and vice versa.

double word
mot m double

A facility of some microcomputers where two words can be implemented as a double-length word. This allows an 8-bit word computer to be used as a 16-bit word computer.

downloading
chargement m descendant

Downloading. A term describing the taking of data from a large machine (mainframe) to a smaller machine (microcomputer). A telephone, radio, or television can be used to connect the two together.