 Sinclair would shortly stop producing calculators and instead focus on computers , starting with the MK14 in 1977 . The loss of the calculator market was due in part to technological development leading to smaller and cheaper components , which put heavy pressure on profit margins . An import levy of up to 17 @.@ 5 % was placed on components , but the duty for calculators imported from Japan or Hong Kong could be as little as 5 % , making it unprofitable to produce calculators in the UK . Sinclair also had some problems with the reliability of earlier calculators that had adversely affected its reputation , but the Sovereign was sold with a " full and unconditional " five year guarantee . 
 Sinclair would shortly stop producing calculators and instead focus on computers , starting with the MK14 in 1977 . The loss of the calculator market was due in part to technological development leading to smaller and cheaper components , which put heavy pressure on profit margins . An import levy of up to 17 @.@ 5 % was placed on components , but the duty for calculators imported from Japan or Hong Kong could be as little as 5 % , making it unprofitable to produce calculators in the UK . Sinclair also had some problems with the reliability of earlier calculators <a href='null_relcl' title='1'><mark>that</mark></a><a href='been_done' title='2'><mark>had</mark></a> adversely affected its reputation , but the Sovereign was sold with a " full and unconditional " five year guarantee . 
Sinclair would shortly stop producing calculators and instead focus on computers , starting wit the MK14 in 1977 . The loss of da calculator market was due in part to technological development leading to smaller and cheaper components , which put heavy pressure on profit margins . An import levy of up to 17 @.@ 5 % was placed on components , but tdaduty fa calculators imported from Japan or Hong Kong could be as lil as 5 % , wit it unprofitable to produce calculators in the UK . Sinclair also had some problems with the reliability of earlier calculators done adversely affected its reputation , but thdaovereign was sold with a " full and unconditional " five year guarantee .