Casio MT-40

The Casio Casiotone MT-40 is a musical keyboard, formerly produced by Casio and originally developed for the consumer market. It is 9 voice polyphonic, with 37 main keys and 14 smaller bass keys. Eight notes may be played on the main keys, and one note on the bass. The bass section has one timbre, and the main section has 22, assignable to one of four presets. Like most small Casio keyboards, it also has a drum section with 6 different beats, a tempo knob, and a "fill" button. The fill button plays sixteenth note pulses of either the "snare" or "kick" as long as it is held down. Production started in the early 1980s and ceased shortly thereafter. The successor of the MT-40 came with a gray case, and was sold as the MT-41.

The keyboard is a prime candidate for modification through circuit bending, owing to simple circuits and a series of smaller potentiometers inside for factory adjustments. The relative scarcity of these makes bending relatively risky, and most are left as stock.

The MT-40 had a built-in pattern based on the Eddie Cochran song "Somethin' Else". Because of this, a synthesizer version of the song's bassline ended up as the basis of one of the most popular dancehall music riddims of Jamaican music - the Sleng Teng riddim which started the "Digital Reggae" revolution in 1985.

It has also secured a niche in indie music. It occurs occasionally in songs by The Magnetic Fields and is featured prominently on most of Emperor X's album Tectonic Membrane/Thin Strip on an Edgeless Platform