 Sinclair 's first home computer was the MK14 , which was launched in kit form in June 1978 . It was a long way from being a mass @-@ market product . Its very name – MK standing for " Microcomputer Kit " – was indicative of its origins as a product developed by , and for , hobbyists . It had no screen but instead used an LED segment display ( though Science of Cambridge did produce an add @-@ on module allowing it to be hooked up to a UHF TV ) ; it had no case , consisting of an exposed circuit board ; it had no built @-@ in storage capabilities and only 256 bytes of memory ; and input was via a 20 @-@ key hexadecimal keyboard . Despite the limitations of the machine it sold a respectable 10 – 15 @,@ 000 units ; by comparison , the much more expensive Apple II had only sold 9 @,@ 000 units in the United States , a much bigger market , in 1978 . This success convinced Clive Sinclair that there was an untapped market for low @-@ cost computers that could profitably be exploited . 
