A drum machine is an electronic musical instrument that creates percussion sounds, drum beats, and patterns. Drum machines may imitate drum kits or other percussion instruments, or produce unique sounds, such as synthesized electronic tones. A drum machine often has pre-programmed beats and patterns for popular genres and styles, such as pop music, rock music, and dance music. Most modern drum machines made in the 2010s and 2020s also allow users to program their own rhythms and beats. Drum machines may create sounds using analog synthesis or play prerecorded samples. While a distinction is generally made between drum machines (which can play back pre-programmed or user-programmed beats or patterns) and electronic drums (which have pads that can be struck and played like an acoustic drum kit), there are some drum machines that have buttons or pads that allow the performer to play drum sounds "live", either on top of a programmed drum beat or as a standalone performance. Drum machines have a range of capabilities, which go from playing a short beat pattern in a loop, to be able to program or record complex songs arrangements with changes of meter and style. Drum machines have had a lasting impact on popular music in the 20th century. The Roland TR-808, introduced in 1980, significantly influenced the development of dance music, especially electronic dance music, and hip hop. Its successor, the TR-909, introduced in 1983, heavily influenced techno and house music. The first drum machine to use samples of real drum kits, the Linn LM-1, was introduced in 1980 and adopted by rock and pop artists including Prince and Michael Jackson. In the late 1990s, software emulations began to overtake the popularity of physical drum machines housed in a separate plastic or metal chassis. History Rhythmicon (1930–1932) In 1930–32, the innovative and hard-to-use Rhythmicon was developed by Léon Theremin at the request of Henry Cowell, who wanted an instrument that could play compositions with multiple rhythmic patterns, based on the overtone series, that were far too hard to perform on existing keyboard instruments. The invention could produce sixteen different rhythms, each associated with a particular pitch, either individually or in any combination, including en masse, if desired. Received with considerable interest when it was publicly introduced in 1932, the Rhythmicon was soon set aside by Cowell and was virtually forgotten for decades. The next generation of rhythm machines played only pre-programmed rhythms