The New York Times writes:
The cassette-playing Walkman, even though it was outrageously successful, did not help Sony prepare for the digital player. The Walkman was nothing but hardware, and surprisingly simple. The first one was built in 1979, when a Sony executive sent a request to the company’s tape recorder unit to rig up a portable cassette player that could provide stereo sound but still be light enough for him to take along on international flights. A small team pulled out the recording mechanism and speaker of the company’s monaural Pressman, a cassette recorder used by journalists, installed stereo circuitry and added earphones. It was ready in four days.
The predigital Walkman evolved over the years into more than an astounding 1,120 models. But its essential nature remained unchanged: it was dumb hardware. When Apple Computer introduced the iPod in November 2001, Steve Jobs described his new player as “the 21st-century Walkman.” With 98 years remaining in the century, that was an early call. But he was correct. The iPod in 2001 was a Walkman successor, but smarter, its hard drive easily navigated with well-designed software.
In April 2003, however, when the iTunes Music Store opened, the iPod became something else again: part of an ingeniously conceived blend of hardware, software and content that made buying and playing music ridiculously easy. Apple accomplished this feat by relying on its own expertise in the twin fields of hardware and software, but without going into the music business itself.