Walkman: A História Ilustrada (1979–2004) A timeline of Sony’s cassette Walkman models from 1979 to 2004 - EP.17 - 1987: SONY WALKMAN WM-501

 

By 1987, the WM-501 gained recognition through its monkey-themed commercials. It integrated

 a gumstick battery into the body, shrinking the player to roughly cassette size, and introduced

Deep Bass Boost.