The compact cassette began as a way to make office dictation less tedious and ended up in pockets, car dashboards, and revolutions. This episode starts with the clumsy reel-to-reel machines of the postwar years and the failed RCA tape cartridge of 1958, then follows Philips as it set two design teams against each other. Lou Ottens and his group in Hasselt, Belgium won with a two-hole design unveiled at the Berlin Radio Show in August 1963. Pressed by Sony, Philips licensed the format free of charge, and Grundig’s rival DC International was gone by 1967.

Sound quality came next. Tape crawling at one and seven eighths inches per second hissed badly until 1971, when the Advent Corporation paired Dolby B noise reduction with chromium dioxide tape. The episode explains companding, bias, and why decks eat tapes, then turns to what the format made possible: the Sony Walkman of July 1st, 1979, home multitrack recording, smuggled sermons and protest songs, and computer programs stored as screeching tones.

• The Walkman TPS-L2 sold over 300 million units, and by 1983 cassettes had overtaken vinyl as the most popular music format in the United States.
• Ayatollah Khomeini’s sermons were copied onto cassettes and passed hand to hand across Iran in 1979, and banned music spread the same way in Pinochet’s Chile.
• TEAC’s Portastudio, introduced in 1979, let musicians record four independent tracks on one cassette at home.
• European radio stations broadcast software over the air so listeners could tape it and load it into 8-bit computers like the Commodore 64.
• The last new car sold in the U.S. with a factory tape deck was the 2010 Lexus SC430, yet National Audio Company began making new tape stock in 2018.