The Rhodes piano (also known as the Fender Rhodes piano) is an electric piano invented by Harold Rhodes, which became popular in the 1970s. Like a conventional piano, the Rhodes generates sound with keys and hammers, but instead of strings, the hammers strike thin metal tines, which vibrate next to an electromagnetic pickup. The signal is then sent through a cable to an external keyboard amplifier and speaker. The instrument evolved from Rhodes's attempt to manufacture pianos while teaching recovering soldiers during World War II. Development continued after the war and into the following decade. In 1959, Fender began marketing the Piano Bass, a cut-down version; the full-size instrument did not appear until after Fender's sale to CBS in 1965. CBS oversaw mass production of the Rhodes piano in the 1970s, and it was used extensively through the decade, particularly in jazz, pop, and soul music. It was less used in the 1980s because of competition with polyphonic and digital synthesizers such as the Yamaha DX7 and an inconsistent quality control caused by cost-cutting. In 1987, the company was sold to Roland, which manufactured digital versions of the instrument without authorization from Harold Rhodes. In the 1990s, the instrument experienced a resurgence in popularity, resulting in Rhodes re-obtaining the rights to the piano in 1997. Although Harold Rhodes died in 2000, the Rhodes piano has since been reissued, and his teaching methods are still in use. The Rhodes piano's keyboard is laid out like a traditional acoustic piano, but some models contain 73 keys instead of 88. The 73-key model weighs around . The keyboard's touch and action is designed to be like an acoustic piano. Pressing a key results in a hammer striking a thin metal rod called a tine connected to a larger "tone bar". The tone generator assembly acts as a tuning fork as the tone bar reinforces and extends the tine's vibrations. A pickup sits opposite the tine, inducing an electric current from the vibrations like an electric guitar.