Drum machine
The Roland TR-909 Rhythm Composer, commonly known as the 909, is a drum machine introduced by Roland Corporation in 1983, succeeding the TR-808. It was the first Roland drum machine to use samples for some sounds, and the first with MIDI functionality, allowing it to synchronize with other devices. Though a commercial failure, it influenced the development of electronic dance music genres such as techno, house and acid house.
Development.
The TR-909 succeeded the previous Roland drum machine, the TR-808. It was designed by Tadao Kikumoto, who also designed the Roland TB-303 synthesizer. The chief Roland engineer, Makoto Muroi, credited the software design to Atsushi Hoshiai and the analog and pulse-code modulation voice circuits to "Mr Ou". 
The 909 was the first Roland drum machine to use samples, for its crash, ride and hi-hat sounds. Hoshiai sampled his own kit for the cymbals, using a mismatched pair of Paiste and Zildjian hi-hat cymbals. He sampled them in 6-bit and edited the waveform on a computer with a CP/M-80 operating system. 
Other sounds are generated with analog synthesis. According to a Roland representative, the engineers felt that samples had some disadvantages and so opted for a combination of sampled and analog sounds.
Sounds and features.
Whereas the 808 is known for its "boomy" bass, the 909 sounds aggressive and "punchy". It has 11 percussion voices and offers sounds for bass drum, snare, toms, rimshot, clap, crash cymbal, ride cymbal and hi-hat (open and closed). It omits the clave, cowbell, maracas, and conga sounds from the 808. The bass has controls for attack and decay. The snare has controls for tone and "snappy", which adjusts the amount of the snare wire sound. As the clap and snare are generated via the same noise source, they produce a phasing effect when played together.
The 909 features a sequencer that can chain up to 96 patterns into songs of up to 896 measures, and offers controls including shuffle and flam. Users can add accents to beats. The 909 was the first Roland drum machine to use MIDI, allowing it to synchronize with other MIDI devices, or to allow sounds to be triggered by an external MIDI controller for wider dynamic range. Older Roland machines can be synchronized via its DIN sync port.
Release.
The 909 was released in 1983 and retailed for $1,195 USD, . It attracted interest in the industry as the first Roland instrument to use digital sounds.
In its review, "Electronics &amp; Music Maker" found the 909 easier to use than the 808 and felt it offered the best analog drum sounds on the market. It concluded that it offered a good combination of analog and sampled sounds and that the addition of MIDI brought the 909 "as up to date as it needs to be". "One Two Testing" found the 909 "gloriously easy to use", but felt it was overpriced and "still sounds like a drum "machine", instead of a machine playing drums ... It lacks the authenticity of real sounds for studio work."
The 909 was a commercial failure, as users preferred the more realistic sampled sounds of competing products such as the LinnDrum. Roland ceased production after one year, having built 10,000 units. Roland changed elements of the 909 in later revisions, correcting problems and adjusting sounds. Some users modify their machines to match sounds from earlier revisions.
Legacy.
Whereas the TR-808 was important in the development of hip hop, the 909, alongside the 303 synthesizer, influenced dance music such as techno, house and acid. According to Gordon Reid of "Sound on Sound", "Like the TR-808 before it, nobody could have predicted the reverence in which the TR-909 would eventually come to be held."
The first known commercial use of a 909 is on the EP "Remission" by the industrial band Skinny Puppy, released months after the 909. In the late 1980s, the 909 was popularized by Chicago house and Detroit techno producers such as Derrick May, Frankie Knuckles and Jeff Mills, who bought second-hand units. DJ Sneak said that "every Chicago producer was using the 909". "Mixmag" described Mills as the "master" of the 909. Mills said its design made it possible to "play" the 909 rather than just program it, using the tuning controls to imitate the feel of a live drummer.
The 909 was used on hip-hop records by acts including Boogie Down Productions, Ultramagnetic MCs, Jazzy Jeff and the Fresh Prince and Public Enemy. Kurtis Mantronik used the 909 on records by his hip hop group Mantronix and records he produced for other artists, such as "Back to the Old School (1986)" by Just-Ice. In the early 1990s, the Japanese composer Yuzo Koshiro incorporated samples of the 909 in his soundtracks for the "Streets of Rage" games. That decade, the 909 was adopted by pop musicians such as Madonna and Pet Shop Boys, and by rock and alternative musicians. Mark Bell used it to create "militaristic" percussion for Björk's 1997 song "Hunter", and Radiohead used it on "Videotape", from their 2007 album "In Rainbows". Electronic artists such as Kirk Degiorgio and Cristian Vogel created sample libraries by recording their friends' machines. 
The 909 was succeeded in 1984 by the TR-707, which uses samples for all its sounds. In 2017, Roland released the TR-09, a smaller version of the 909 with additional features.
References.
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