Selectric

The IBM Selectric typewriter was a highly successful model line of electric typewriters introduced by IBM on 31 July 1961.

Instead of the "basket" of individual typebars that swung up to strike the ribbon and page in a traditional typewriter, the Selectric had a type element (frequently called a "typeball", or more informally, a "golf ball") that rotated and pivoted to the correct position before striking. The type element could be easily changed so as to print different fonts in the same document, resurrecting a capability that had been pioneered by the Blickensderfer typewriter almost 70 years before. The Selectric also replaced the traditional typewriter's moving carriage with a paper roller ("platen") that stayed in position while the typeball and ribbon mechanism moved from side to side.

The Selectric mechanism was notable for using internal mechanical binary coding and two mechanical digital-to-analog converters, called whiffletree linkages, to select the character to be typed.

Selectrics and their descendants eventually captured 75 percent of the United States market for electric typewriters used in business. IBM replaced the Selectric line with the IBM Wheelwriter in 1984 and transferred its typewriter business to the newly formed Lexmark in 1991.

The Selectric typewriter was introduced on 23 July 1961. Its industrial design is credited to influential American designer Eliot Noyes. Noyes had worked on a number of design projects for IBM; prior to his work on the Selectric, he had been commissioned in 1956 by Thomas J. Watson, Jr. to create IBM's first house style: these influential efforts, in which Noyes collaborated with Paul Rand, Marcel Breuer, and Charles Eames, have been referred to as the first "house style" program in American business.

The Selectric remained unchanged until 1971 when the Selectric II was introduced. The original design was thereafter referred to as the Selectric I. These machines used the same 88-character typing elements. However they differed from each other in many respects:

...
Wikipedia