The invention relates to a computer theory tester which can convert control signal in one time, belonging to computer teach tester technical field. The invention comprises a math logic elements, an accumulator, a first, a second, and a third registers, a tri-state door, a data switch, a memory, a convert switch, a selector for selecting one of first and second registers, a program counter, an address counter, a command register, an operand decoder, a sequence timer, a micro program controller, and a combined logic controller. The invention has the advantages that the invention can meet the computer theory tester of micro program controller and logic controller, while user can dial a dual-bit switch to switch between micro program controller and combined logic controller.