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

The feature explosion continued, with personal stereos adding FM tuners, sometimes in the shape of a fake cassette tape. Some could be added to docking stations, while others added high-fidelity recording features. Size became increasingly important, with vendors vying to produce the smallest and lightest hardware - eventually, some players were even smaller than the cassette tape they were playing, simply clipping around one edge of the cassette.

Closely related to the compact cassette, microcassettes were introduced in 1969, and were commonly used for low-fidelity voice recordings and dictation because you could record significant amounts of material on a single small cassette. The tape used was thinner, and the tape speed a quarter of that of its larger predecessor. Most microcassette recorders allow a choice of recording speeds and qualities, as well as offering variable speed playback to aid in transcription. Microcassette recorders were ideal for concert bootlegging, as they could easily be smuggled into a concert.

We've grown used to combination devices, like cassette players with built-in CD players and MP3 players with FM radios. They're not a late 20th century phenomenon - the first combination radio/gramophone was advertised in 1922 for less than $500. The smaller form factor of the cassette tape was the boost needed for the explosion of radio-cassettes in the late 1970s and 1980s. Some were more portable than others, though - some of the later boomboxes, with their arrays of bass speakers, pay only lip service to the idea of portability.

Digital reached the airwaves in 2001 with satellite radio, with a menu of stations available nationwide, information about each song as it plays, and no static - if the signal is poor, for example in the mountains, the sound doesn't break up, but it may cut out altogether. Digital receivers for XM and Sirius satellite radio were initially restricted to in-car units and some enthusiasts adapted them for portable use by wiring in batteries. XM launched the $350 MyFi in late 2004, a handheld portable satellite radio that could also record up to five hours of programming.

Europe and the UK use a different digital radio system known as Digital Audio Broadcasting (DAB); this has been available since the mid 1990s, and a range of in-car and portable radios are available.