A type of printer that produces characters and illustrations by striking pins against an ink ribbon to print closely spaced dots in the appropriate shape. Dot-matrix printers are relatively expensive and do not produce high-quality output. However, they can print to multi-page forms (that is, carbon copies), something laser and ink-jet printers cannot do.
Dot-matrix printers vary in two important characteristics:
speed: Given in characters per second (cps),the speed can vary from about 50 to over 500 cps. Most dot-matrix printers offer different speeds depending on the quality of print desired.
print quality: Determined by the number of pins (the mechanisms that print the dots), it can vary from 9 to 24. The best dot-matrix printers (24 pins) can produce near letter-quality type, although you can still see a difference if you look closely.
In addition to these characteristics, you should also consider the noise factor. Compared to laser and ink-jet printers, dot-matrix printers are notorious for making a racket.
- dot pitch
Also called phosphor pitch, a measurement that indicates the diagonal distance between like-colored phosphor dots on a display screen. Measured in millimeters, the dot pitch is one of the principal characteristics that determines the quality of display monitors. The lower the number, the crisper the image. The dot pitch of color monitors for personal computers […]
- double click
Tapping a mouse button twice in rapid succession. Note that the second click must immediately follow the first, otherwise the program will interpret them as two separate clicks rather than one double click. In Microsoft Windows and the Macintosh interface, you can use a double click to open files and applications. Both systems let you […]
- double-density disk
A floppy disk that has twice the storage capacity of a single-density floppy. Single-density disks are now obsolete. Double-density 5¼-inch disks for PCs can hold 360K of data. Double-density 3½-inch disks can hold 720K.
In online forums double posting is when a user posts the same message or slightly edited versions of the message more than once, in more than on discussion thread. Double-post is also called cross-post.
- double precision
Refers to a type of floating-point number that has more precision (that is, more digits to the right of the decimal point) than a single-precision number. The term double precision is something of a misnomer because the precision is not really double. The word double derives from the fact that a double-precision number uses twice […]