Scientist retrospective published in 1986 commented: High-profile advertising was central to the marketing campaign. Although Sinclair Research was a relatively small company, it had a long-standing policy of using large-scale advertisements that stood out in stark contrast to the more muted advertisements of other manufacturers. Superlatives, exhortations, appeals to patriotism, testimonials, eye-catching drawings and photographs on double-page spreads, varying from month to month, were used to drum up mail order business for Sinclair. The launch advertising for the ZX81 illustrates this approach. A photograph of the ZX81 alongside the official Sinclair peripherals dominated the centre of a double-page spread. The value for money of Sinclair's products was emphasised by the prices being printed in larger type than any other text on the spread. The ZX81's benefits were promoted with the aspirational slogan "Sinclair ZX81 Personal Computer – the heart of a system that grows with you". The advertisement highlighted ZX81 BASIC Programming, the manual written by Steve Vickers, as "a complete course in BASIC programming, from first principles to complex programs." The educational benefits of the ZX81 were stressed ("it's still very simple to teach yourself computing") and its technical advantages were explained in relatively non-technical terms. For instance, the ZX81's idiosyncratic method of typing commands with a single keystroke – the result of the memory-saving method of using one-byte tokens to represent keywords – was presented as "eliminat[ing] a great deal of tiresome typing". The ZX81's British character was emphasised; it was "designed by Sinclair and custom-built in Britain." Sinclair's advertising in the United States provides an illustration of how the company perceived the ZX81's purpose: This approach to advertising was driven by Sinclair's reliance on mail-order marketing. It came with a high up-front cost in terms of purchasing space in publications but it had the advantage of ensuring that all sales were firm and pre-paid. A big splash on launch produced a large influx of cash at the outset of a campaign, though it did also depend on the advertiser having enough product to satisfy the initial surge in demand. The advertisements served an additional purpose of priming the market for over-the-counter sales by "getting the story across", as Clive Sinclair put it: "Not that big a proportion do buy on mail order, but they see the ads, and that helps to prepare them for buying when the item appears in the shops." Sinclair himself became a focal