4. Tapes: From 4-Track To Cassettes, Continued

The compact cassette was introduced by Phillips in 1963, arriving in the US in 1964. Using the same underlying magnetic tape technology as its reel-to-reel predecessors, compact cassettes used four tracks to encode two stereo tracks as two sides. Over time, improvements in tape composition resulted in higher and higher fidelity recording, leading to the release of the type IV metal-based tape in the 1980s.

Portable cassette players were an early introduction, arriving in 1963. Initially, battery-powered mono devices were sold as portable voice recording devices, but were soon used for playing back pre-recorded music. The cassette remained a portable medium, with portable stereo players following quickly, usually with mixed battery and A/C power supplies. The portable cassette player grew in two directions: downwards to the headphone-only Walkman-style device, and upwards to the bass-heavy boombox. The wide variety of form factors continued, with the addition of combined CD-radio-cassette players in the later 1980s and early 1990s.

In-car versions of cassette players followed quickly; they became standard equipment on many cars, replacing the 8-track. Car cassette players were smaller than their 8-track predecessors, and could easily be combined with a radio in a single unit. As auto-reverse and track skipping technologies were developed, they quickly were added to car cassette players, making it easier for a driver to manage music on the move.

The original 1979 Sony Walkman had two headphone jacks, so you could listen with a friend.

The Sony Walkman arrived in 1979, introducing the concept of the personal stereo device. Stripping out many of the components of a standard portable cassette player, the Walkman could be clipped to a belt, and used headphones connected to a 3.5 mm stereo jack to play music on the go. The first Sony Walkman had two stereo headphone jacks, so two people could listen together, but this feature was quickly dropped. Competition soon followed, and the Walkman brand became the popular name for the entire category. Devices added features, including noise reduction, auto reverse, remote controls and track skip, and new motor technologies allowed longer battery life and lighter devices.