but able to both preserve the program for later broadcast and allowing the possibility of retakes (still rare since videotape editing required a razor blade and was not done unless absolutely necessary). In Britain, from the very beginning of regular television broadcasting in 1936 until the 1980s, interior scenes for television drama and comedy shows were shot with electronic cameras, while exterior scenes were shot with 16-mm film cameras. This arrangement conditioned British viewers to identify a "live" look with interior scenes and a "film" look with exterior scenes. In the U.S. and West Germany, most shows were produced completely in either film or video to avoid jarring difference in frame rate. Most other countries avoided outdoor shots for television productions as much as they could until portable video cameras became available. By the early 1960s, about 90% of U.S. households had a television set, and the roles of television and radio had changed significantly. Radio was largely saved from obsolescence by the invention of the far more portable transistor radio in the 1950s and the concurrent rise of higher-fidelity FM radio, so that radio became primarily a medium for music, while scripted programming became wholly the domain of television. Evolution of high-culture drama on television The early days of television introduced hour-long anthology drama series, many of which received critical acclaim. Examples include Kraft Television Theatre (debuted May 7, 1947), The Chevrolet Tele-Theatre (debuted September 27, 1948), Television Playhouse (debuted December 4, 1947), The Philco Television Playhouse (debuted October 3, 1948), Westinghouse Studio One (debuted November 7, 1948), and Your Show Time (debuted January 21, 1949). High culture dominated commercial network television programming in the 1950s with the first television appearances of Leonard Bernstein (on Omnibus) and Arturo Toscanini, the first telecasts from Carnegie Hall, the first live U.S. telecasts of plays by Shakespeare, the first telecasts of Tchaikovsky's ballets The Sleeping Beauty and The Nutcracker, and the first opera specially composed for television, Gian Carlo Menotti's Amahl and the Night Visitors. The Bell Telephone Hour, an NBC radio program, began its television run featuring both classical and Broadway performers. The networks employed art critics, notably Aline Saarinen and Brian O'Doherty, something that was mostly discontinued by the start of the digital television era (CBS's John Leonard being the last of significance). As a new medium, television introduced many innovative programming concepts, such as the diverse cultural programs of