1. A method of conditional data processing operation comprising the steps of: setting a condition to either a first state or a second state; performing a first arithmetic/logical operation and storing a first result in a first data register with a first write priority; and conditionally moving predetermined data into said first data register if said condition has said first state with a second write priority, said second write priority of said conditional move being higher than said first write priority of said first arithmetic/logical operation whereby said first data register stores said predetermined data if said condition has said first state or said first result of said first arithmetic/logical operation if said condition does not have said first state.