 The marketing of the ZX81 was handled by Sinclair 's long @-@ standing marketing agency Primary Contact ( now part of Ogilvy & Mather ) , which had provided marketing services for Sinclair since 1971 and was to continue doing so until 1985 . Sinclair 's entry into the nascent home computing market gave Primary Contact a major challenge – how to market a product simultaneously at hobbyists and at the " man on the street " , who probably had little or no computer literacy . The answer was to pursue what the journalist David O 'Reilly of MicroScope magazine described as a single @-@ minded " user @-@ friendly strategy . " Chris Fawkes , one of Primary Contact 's directors , explained : " We brought personal computers to the mass market by showing that you didn 't have to be a whizzkid to use one . " As Clive Sinclair put it in a 1982 interview with Your Computer , 
