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The LM-1 Drum Computer, manufactured by Linn Electronics Inc., was the first drum machine to use digital samples of acoustic drums. Conceived and designed by Roger Linn, it was also one of the first programmable drum machines. It was introduced in early 1980 at a list price of US$4,995, climbed to $5,500 when additional features were incorporated, fell to $4,995 as cost-cutting measures were introduced, and later reduced to $3,995 before it was discontinued after the release of its successor, the LinnDrum. It is prized by amateur and professional musicians alike for its rarity as well as its characteristic sounds, which can be heard on the recordings of such famous artists as Prince, Michael Jackson, The Human League, Peter Gabriel, Kraftwerk and countless other pop hits of the 1980s.
Roger Linn was a semi-professional guitarist in California in 1978 when he began to develop the LM-1 as an accompaniment tool for his home studio. He had experimented with many of the preset rhythm boxes which were popular at the time, but was dissatisfied and "wanted a drum machine that did more than play preset samba patterns and didn't sound like crickets."  Having learned how to program in BASIC and assembly language, Linn set to work on a computer program which could play user-programmed rhythm patterns, as well as chain them together to form a song.
According to Linn, the first to suggest the idea of digital samples was Steve Porcaro of Toto. Linn himself doesn't remember exactly who played the sounds used for the samples; it has been suggested that they were a combination of several Los Angeles session drummers, possibly James Gadson, Art Wood, Ron Tutt, or Steve's brother Jeff Porcaro, also of Toto.
Linn achieved his sounds by using a chip, built into the machine, which converted the digital samples into analog audio. His first prototype, manufactured some time during 1979, was a cardboard box which contained the electronic components of the drum machine. Supposedly, Linn brought this prototype to parties and jobs and marketed it to fellow musicians, including Peter Gabriel, the members of Fleetwood Mac, and Stevie Wonder, who bought one of the first units ever produced.
In total, approximately 725 units were built and sold between 1980 and 1983, when the LM-1's successor, the LinnDrum, was released. The first 35 units were assembled in Linn's home, before manufacturing and distribution was taken over by 360 Systems, run by Bob Easton. The first 10 of these 35 units have somewhat unique characteristics, as described below.
The LM-1's many features set it apart from other drum machines of its time, most of which could only play a limited selection of preset rhythms (i.e. Roland CompuRhythm CR-78). One of its most prominent features was its programmability. Although the Linn LM-1 was not the first programmable drum machine (the PAiA Programmable Drum Set was released 6 years earlier), it was the first to use digital samples and gained widespread popularity among professionals. The LM-1 also introduced a shuffle feature that enabled users to program swing notes into their rhythms. Although this feature has often been imitated, the Linn shuffle has widely been recognized as the best and most natural-sounding, and is present on every device Linn designed, including the Akai MPC series.
The LM-1 included a built-in 13-channel mixer (one channel for each sound) as well as individual output jacks. This enabled Linn's machine to integrate with existing recording equipment in a way that had previously not been possible for a drum machine. Unlike the later Linndrum, the LM-1 also had individual tuning pots for each voice, resulting in many famous users expressing their preference for the LM-1 long after the Linndrum was introduced. Unlike its younger brother, the LM-1 lacked crash and ride cymbal sounds (which producers easily compensated for by having live cymbals overdubbed onto whatever track was being recorded) and the drum sounds could not be triggered by MIDI or trigger inputs. Nevertheless, the LM-1's sounds are very punchy and prominent.
There are notable differences between the various LM-1 revisions. The Rev. 1 LM-1 is recognizable by its engraved buttons and lack of shuffle LEDs. The drum buttons were engraved with a small symbol of the drum it represented (the bass drum button had a small engraving of a bass drum on it). These buttons were later discontinued because they were too expensive to manufacture. Internally it was different as well. It had single chips for the kick, tom, and conga sounds, and double chips for the clap. The Rev. 1 LM-1's did not have the filter on the kick, toms, and congas that Rev. 2 and later machines had. As a result, it didn't sound as nice as the Rev. 2 and later machines, but the toms and congas could be played simultaneously.
In the Rev.1 LM-1s, the first 10 have no serial numbers or pre-printed, adhesive-backed manufacturer's label on the rear panel, have a single molded metal frame for the front, bottom, and rear panels, have higher quality mixer pots, have two knobs for tempo control (coarse and fine; the fine control actually may have been intended for a rotary switch to program the shuffle setting), and are screen printed "Linn and Moffett Electronics" instead of "Linn Electronics" on the lower right front of the chassis beneath the drum buttons (Moffett was an early investor in the Linn drum computer development). There are other minor mechanical differences, too.
The Rev. 2 LM-1 introduced two rows of LEDs to indicate the shuffle and quantize settings, several additional buttons on the front panel to aid in programming, and a shared filter on the toms and congas, as well as the kick drum. There were a handful of Rev. 2 LM-1's with both engraved buttons and shuffle LEDs but these are extremely rare.
Cost-cutting measures were introduced to later Rev. 2's such as removing the engraved buttons and adding the drum names to the front panel, removing the sync input jack and sync output knob from the back of the machine (the current quantize setting became the default sync output rate), removing the low volume stereo outputs, decreasing the size of the play/stop button, and replacing the raised buttons with sealed buttons (flush with the surface) that were impossible to clean. In fact, the LM-1 service notes indicated these buttons had to be replaced if they went bad.
Because of the Linn LM-1's versatility, it superseded its intended purpose as an accompaniment tool and became a fully-fledged rhythm section for many synthpop and progressive acts. Along with the Roland TR-808, which was released around the same time, it is widely credited with legitimizing drum machines which, with a few notable exceptions, had previously largely been considered toys by most professional, mainstream musicians.
It was thought for a time that the LM-1 would put every session drummer in Los Angeles out of business, and caused enough of a stir that many leading session drummers (such as Jeff Porcaro of Toto, for example) went out and purchased their own drum machines and offered "programming" services (Porcaro used an LM-1 on George Benson's 1982 hit "Turn Your Love Around").
The first song featuring an LM-1 to hit #1 on the UK pop chart was the Human League's "Don't You Want Me", in late 1981. It is also the first LM-1 track to top the US Billboard Hot 100, spending four weeks there in July 1982.
In some ways the most important and lasting of the LM-1's various features is its sounds, which remain powerful and characteristic and a familiar staple of 1980s pop music. Linn acknowledged that his lack of audio engineering know-how may have contributed to his drum machine's unique sound - many of the samples contain playback frequencies above the Nyquist frequency which, although it results in aliasing under normal circumstances, contributes much to the "sizzle" of the LM-1's sound. 
Linn introduced the successor to his revolutionary machine in 1982. The LinnDrum often erroneously called the LM-2 (LM-1 stood for Linn/Moffett/1 and Moffett wasn't with the company by the time the LinnDrum came around), contained more sounds (including cymbals), more options for programming sounds (step programming mode), and 5 programmable trigger inputs, but was a step back from the LM-1 in that it removed the ability to tune all of the individual drum sounds (hi-hat, bass, cowbell, tambourine, sidestick, and many other sounds were no longer tunable). It retailed for $2,500 less than the original LM-1 and although it added some additional features, the cost-cutting measures were quite notable. Although the LinnDrum helped make electronic drums more affordable for the common musician, they are still not as revered as the LM-1 and generally can be found on the used market for much less.