Dot matrix printing or impact matrix printing is a type of computer printing which uses a print head that runs back and forth, or in an up and down motion, on the page and prints by impact, striking an ink-soaked cloth ribbon against the paper, much like the print mechanism on a typewriter. However, unlike a typewriter or daisy wheel printer, letters are drawn out of a dot matrix, and thus, varied fonts and arbitrary graphics can be produced.
Text quality used to a problem with dot-matrix printers. Near Letter Quality mode changed that making dot matrix printers good enough for most business uses.
24 Pin Printers
The 24-pin impact printer produces better looking NLQ text and it is faster because it can print NLQ in a single pass.
Dot matrix printers, like any impact printer, can print on multi-part stationery or make carbon copies. Impact printers have one of the lowest printing costs per page. As the ink is running out, the printout gradually fades rather than suddenly stopping partway through a job. They are able to use continuous paper rather than requiring individual sheets, making them useful for data logging.
See the Okidata Microline 320 Turbo for an example of impact printers by Okidata.