Patent US 4,954,947

An instruction processor effecting operations for register operands and for processing branch instructions to perform address calculations for branch destination instructions, comprising general-purpose registers storing data including results of operations of said instruction processor, address adders calculating the address of branch destination instructions by using data read out from the general-purpose register and an ALU performing arithmetical or logical operations on the data read out from the general-purpose register in the decode cycle of the instructions. The result of the arithmetical or logical operation is inputted into the address adder but not from the general-purpose register, in the case where the result of the arithmetical or logical operation is utilized for address calculation in the execution of a succeeding instruction.