🔗 IBM Selectric Typewriter

🔗 Typography 🔗 Industrial design

The IBM Selectric typewriter was a highly successful 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 typical typewriter of the period, the Selectric had an "element" (frequently called a "typeball", or less formally, a "golf ball") that rotated and pivoted to the correct position before striking. The element could be easily changed so as to use different fonts in the same document typed on the same typewriter, resurrecting a capability that had been pioneered by typewriters such as the Hammond and Blickensderfer in the late 19th century. The Selectric also replaced the traditional typewriter's horizontally moving carriage with a roller (platen) that turned to advance the paper but did not move horizontally, while the typeball and ribbon mechanism did.

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. By its 25th anniversary, in 1986, a total of more than 13 million machines were made and sold.