 The ZX81 's distribution arrangements were an essential part of its success and marked a watershed in the way that computers were sold in the UK . Sinclair had previously made its name as a mail @-@ order retailer – the ZX81 was initially available only through mail @-@ order – but the only truly effective way to reach the mass market was via high street stores . Fortunately for Sinclair , an opportunity to do just that was provided by W.H. Smith , a venerable <unk> and magazine @-@ seller and stationery chain . The company had stagnated in the 1970s and was looking for ways to revitalise its image and expand its product range . 
