Early microcomputers often used punched tape for data storage, until in 1975 Jerry Ogdin and Les Solomon co-authored an article in Popular Electronics magazine about using inexpensive Compact Cassettes with audio tones to represent the binary data.
Many home computers of the late 1970s and early 1980s subsequently used cassettes for data storage as a cheaper alternative to paper tape or the floppy disks increasingly used in high-end microcomputers.
Typical speeds of loading were from 500 to 2000 bits per second, although some games used special, faster-loading routines, up to around 4000 bit/s. A rate of 2000 bit/s equates to a capacity of around 660 KB per side of a 90-minute tape.
Any type of Compact Cassette could be used, but smaller length cassettes such as C10 and C15 were produced for recording data.
Floppy disk storage become more prevelant by the mid-1980s, but cassettes remained popular for 8-bit computers such as the Commodore 64 and ZX Spectrum, particularly in the UK. Reliability of cassettes were variable, and multiple attempts to load programmes were sometimes required.