The introduction of the ZX Spectrum led to a boom in companies producing software and hardware for the machine, the effects of which are still seen. The Spectrum was among the first home computers in the United Kingdom aimed at a mainstream audience, similar in significance to the Commodore 64 in the US or the MO5 in France. The Spectrum was released as eight different models, ranging from the entry level with 16 KB RAM released in 1982 to the ZX Spectrum +3 with 128 KB RAM and built in floppy disk drive in 1987 altogether they sold over 5 million units worldwide (not counting unofficial clones). Referred to during development as the ZX81 Colour and ZX82, it was launched as the ZX Spectrum to highlight the machine's colour display, compared with the black and white display of its predecessor, the ZX81. It was first released in the United Kingdom on 23 April 1982 and went on to become Britain's best-selling microcomputer. The ZX Spectrum ( UK: / z ɛ d ɛ k s/) is an 8-bit personal home computer developed by Sinclair Research. Compact Cassette, ZX Microdrive, 3-inch floppy disk on Spectrum +3

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