in Los Angeles out of work and it caused many of L.A.'s top session drummers (Jeff Porcaro is one example) to purchase their own drum machines and learn to program them themselves in order to stay employed. Linn even marketed the LinnDrum specifically to drummers. Following the success of the LM-1, Oberheim introduced the DMX, which also featured digitally sampled sounds and a "swing" feature similar to the one found on the Linn machines. It became very popular in its own right, becoming a staple of the nascent hip-hop scene. Other manufacturers soon began to produce machines, e.g. the Sequential Circuits Drum-Traks and Tom, the E-mu Drumulator and the Yamaha RX11. In 1986, the SpecDrum by Cheetah Marketing, an inexpensive 8-bit sampling drum external module for the ZX Spectrum, was introduced, with a price less than £30, when similar models cost around £250. Roland TR-808 and TR-909 In 1980, the Roland Corporation launched the TR-808 Rhythm Composer. It was one of the earliest programmable drum machines, with which users could create their own rhythms rather than having to use preset patterns. Unlike the more expensive LM-1, the 808 is completely analog, meaning its sounds are generated non-digitally via hardware rather than samples (prerecorded sounds). Launched when electronic music had yet to become mainstream, the 808 received mixed reviews for its unrealistic drum sounds and was a commercial failure. Having built approximately 12,000 units, Roland discontinued the 808 after its semiconductors became impossible to restock. Over the course of the 1980s, the 808 attracted a cult following among underground musicians for its affordability on the used market, ease of use, and idiosyncratic sounds, particularly its deep, "booming" bass drum. It became a cornerstone of the emerging electronic, dance, and hip hop genres, popularized by early hits such as Marvin Gaye's "Sexual Healing" and Afrika Bambaataa and the Soulsonic Force's "Planet Rock". The 808 was eventually used on more hit records than any other drum machine; its popularity with hip hop in particular has made it one of the most influential inventions in popular music, comparable to the Fender Stratocaster's influence on rock. Its sounds continue to be used as samples included with music software and modern drum machines. The 808 was followed in 1983 by the TR-909, the first Roland drum machine to use MIDI, which synchronizes devices built by different manufacturers. It was also the first Roland drum machine to