A letter-quality printer was a form of computer impact printer that was able to print with the quality typically expected from a business typewriter such as an IBM Selectric. A letter-quality printer operates in much the same fashion as a typewriter. A metal or plastic printwheel embossed with letters, numbers, or symbols strikes an inked ribbon, depositing the ink on the page and thus printing a character. Over time, several different technologies were developed including automating ordinary typebar typewriter mechanisms, daisy wheel printers where the type is moulded around the edge of a wheel, and "golf ball" printers where the type is distributed over the face of a globe-shaped printhead. The daisy wheel and Selectric-based printers offered the advantage that the typeface was readily changeable by the user to accommodate varying needs. These printers were referred to as "letter-quality printers" during their heyday, and could produce text which was as clear and crisp as a typewriter. Most were available either as complete computer terminals with keyboards that could double as a typewriter in stand-alone mode, or as print-only devices. Because of its low cost at the time, the daisy wheel printer became the most successful, the method used by Diablo, Qume, Brother and Apple. Letter-quality impact printers, however, were slow, noisy, incapable of printing graphics or images, sometimes limited to monochrome, and limited to a fixed set of typefaces without operator intervention, though certain font effects like underlining and boldface could be achieved by overstriking. Soon, dot-matrix printers would offer "Near Letter Quality" modes which were much faster than daisy-wheel printers, could produce graphics well, but were still very noticeably lower than "letter quality". Nowadays, printers using non-impact printing have replaced traditional letter-quality printers in most applications. The quality of inkjet printers can approach the old letter-quality impact printers.
Dedicated word processors and WP software for general-purpose computers that rose in popularity in the late 1970s and 1980s would use features such as microspacing to implement subscripts, proportional spacing, underlining, and so on. The more rudimentary software packages would implement bold text by overtyping the character in exactly the same spot, but better software would print the letter in 3 slightly different positions. Software did exist to produce pie charts on such printers.
