Hep cats still hang out at Johnny Rockets restaurants, where U-shaped counters, padded booths, and white uniforms salute the classic American diner. The company operates and franchises more than 140 restaurants in about 30 US states and a half dozen other countries. Johnny Rockets serves such old-fashioned diner fare as hamburgers, malts, fries, and apple pie ala mode. A nickel in the table-top jukebox brings back the Glenn Miller sound, and crooners such as Frank Sinatra prove they're the bee's knees, Daddy-O. Johnny Rockets is backed by Apax Partners. The chain was founded by Ronn Teitelbaum, who opened the first Johnny Rockets on Los Angeles' fashionable Melrose Avenue in 1986.