as a whole rather than singles. In the early 1970s, many DJs had the freedom to choose which track(s) to play off a given album – as well as latitude to decide in what order to play the records. Consequently, AOR radio gave mainstream exposure to album tracks that never became hits on the record charts that were limited to singles; Billboard, for instance, did not establish an airplay chart for album tracks until 1981. Later in the 1970s, AOR formats became tighter and song selection shifted to the program director or music director rather than the DJ. Still, when an AOR station added an album to rotation, they would often focus on numerous tracks at once, rather than playing the singles as they were individually released. Criticism In the early 1980s, AOR radio was criticized by the Black Music Association, a trade association, and other industry observers for the lack of Black artists included in their programming. AOR programmers responded that the lack of diversity was the result of increased specialization of radio formats driven by ratings and audience demographics. In 1983, the success of Michael Jackson's album Thriller led to the album's track "Beat It," which featured Eddie Van Halen, being added to the playlists of many AOR channels. At the same time, other Black artists also made inroads into AOR radio: Jackson ("Beat It"), Prince ("Little Red Corvette"), and Eddy Grant ("Electric Avenue") debuted on Billboard'''s Top Tracks chart during the same week in April 1983. Through the remainder of the 1980s, Jon Butcher, Tracy Chapman, Living Colour, Prince, and Lenny Kravitz also received AOR airplay. Spin-off formats In the 1980s, some AOR radio stations added glam metal bands such as Mötley Crüe and Bon Jovi, while others embraced modern rock acts such as the Fixx, INXS, and U2. But by the end of the decade, AOR stations were playing fewer and fewer new artists, and the rise of grunge, alternative rock, and hip-hop accelerated the fade-out of the album-oriented rock format. By the early 1990s, many AOR stations switched exclusively to the classic rock format or segued to other current formats with somewhat of an AOR approach: Rock 40 – A service-marked format developed by Joint Communications in 1987 and referred to as "Male CHR" (contemporary hits radio) by Burkhart, Douglas, & Associates, which had difficulty because it was too close to other AOR formats and