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

When did the ibm selectric typewriter come out