The Selectric's spherical typing element moved across a stationary page rather than the traditional swinging typebar mechanism, eliminating jammed keys and enabling far faster, quieter typing. It dominated office typewriting for two decades and became a design icon, with over 13 million units eventually sold before electronic word processors supplanted it.
Traditional typewriters had used swinging metal typebars that struck the ribbon and page, a mechanism prone to jamming whenever a fast typist struck two adjacent keys in quick succession, the very problem that had originally inspired the QWERTY keyboard layout decades earlier. IBM's engineers, led by a team that had been quietly developing the concept since the 1950s, threw out the typebar entirely.
The Selectric instead used a golf-ball-sized metal sphere embossed with reversed characters that rotated and tilted at lightning speed to strike the correct letter, while the sphere itself, rather than the carriage, moved across the stationary paper. This solved jamming almost entirely and allowed typing speeds that outpaced anything before it, while also allowing users to swap the ball to instantly change fonts, a novelty typists found delightful.
The machine became ubiquitous in offices worldwide throughout the 1960s and '70s, and its clacking rhythm became the soundtrack of corporate America. Beyond its commercial success, the Selectric held an odd footnote in Cold War history: Soviet intelligence agents managed to bug a fleet of Selectrics at the US embassy in Moscow, capturing keystrokes via hidden magnetic sensors for years before American technicians discovered the intrusion in the early 1980s.