1. A method of testing memory, comprising: executing each instruction of a plurality of test instructions in sequence, each said instruction having an inactive repeat control field except for a last instruction of each of one or more groups of one or more instructions to be repeated, each said last instruction having an active repeat control field; for each instruction having an active repeat control field: executing in sequence the instructions of the group of instructions with which said each instruction is associated for a predetermined number of repeat cycles for said group; and for each said repeat cycle, modifying predetermined fields of each instruction in accordance with a predetermined field modification instructions for each said repeat cycle.