 The launch of the ZX81 was catalysed in part by the British Broadcasting Corporation 's plan to produce a TV series , to be broadcast in 1982 , aimed at popularising computing and programming . The BBC intended to commission an existing manufacturer to provide it with a BBC @-@ branded home computer to tie in with the series . When Sinclair got wind of the project in December 1980 , he wrote to the BBC informing them that he would be announcing a new version of the ZX80 , to be called the ZX81 , in early 1981 . It would remedy some of the ZX80 's deficiencies and would be both cheaper and more advanced . Sinclair naturally wanted the ZX81 to be a candidate for the BBC contract and lobbied for its adoption . He pointed out that there were already 40 @,@ 000 users of the ZX80 and that by the time the series was broadcast there were likely to be upwards of 100 @,@ 000 ZX81 users ( which turned out to be an underestimate by over 400 @,@ 000 – an indication of how the ZX81 's success exceeded even Sinclair 's expectations ) . 
