IBM Selectric  
Written by Accutron on 2017-04-10  

Devices included in this entry:

IBM Selectric 721 electric typewriter (pictured in thumbnail)
IBM Selectric 723 electric typewriter
IBM Selectric 725 electric typewriter

Introduced on July 23, 1961, the IBM Selectric was a fundamental revolution in typewriter technology. Abandoning the typebar mechanism used in nearly all other typewriters, the IBM Selectric uses a spherical, internchangeable type element, which includes 88 characters arranged in four rings of 22 characters each. The position of the type element is controlled by a whiffletree mechanism which mechanically decodes seven bits of keypress data to position the type element. Two bits select the row, while five bits select the column. Type elements are available in a range of different typefaces, and can be quickly interchanged. The incredibly fast mechanism of the IBM Selectric allows for much higher typing speeds than a traditional typebar mechanism, and avoids the lockup problems associated with typebar mechanisms when accidentally striking more than one key simultaneously. Despite its internal complexity, the entire Selectric mechanism is mechanical, and driven by a single motor.

Upon its introduction, the Selectric immediately commandeered nearly all of the professional typewriter market, displacing typewriters from competing manufacturers as well as IBM's earlier typebar-based electric machines. The Selectric would spawn an entire range of successor products, including the Selectric II and Correcting Selectric II, Selectric III and Selectric Composer. The Selectric mechanism would not be displaced in professional business machines until IBM's introduction of the Wheelwriter and Quietwriter electronic typewriters in the mid-1980s.

IBM Selectric typewriter, 721 variant with 8.5" writing line and cloth ribbon carrier.

IBM Selectric typewriter, 723 variant with 11" writing line and cloth ribbon carrier.

IBM Selectric typewriter, 725 variant with 13" writing line and cloth ribbon carrier.

Selectric 88-charater type element.

This article is part of the [Typewriters] exhibit.

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