Born from the ashes of disco, House music has been one of the more enduring permutations of electronic music. Originating in Chicago in the early 80's, House grew out of the limited pool of dance music available to club DJs at the time. Classic disco and European synthpop was mixed together by DJs like Frankie Knuckles, and soon original music in the same vein was being created by people like Chip E. The common element of house music is a prominent 4/4 beat generated by a drum machine or other electronic means (such as a sampler). As well, house music uses a continuous, repeating (usually also electronically generated) bassline. Typically added to this foundation are electronically generated sounds and samples of music such as jazz, blues and synth pop, as well as additional percussion, along with often sparse vocals. By the late 80's, house had broken out of underground clubs in cities like Chicago, New York, and London, and had begun making inroads on the pop charts, particularly in England and Europe but later in America under the guise of artists like C+C Music Factory and Madonna. At the same time, house was breaking into the pop charts; it fragmented into a number of subgenres, including hip-house, ambient house, and most significantly, acid house (a subgenre of house with the instantly recognizable squelch of Roland's TB-303 bass-line generator). During the 90's, house ceased to be cutting-edge music, yet it remained popular in clubs throughout Europe and America. At the end of the decade, a new wave of progressive house artists including Daft Punk, Basement Jaxx, and House of 909 brought the music back to critical quarters with praised full-length works.