Part of machine instructions consisting of codes indicating the operation to be performed. The balance of the instructions may be addresses of the operands or may also contain the address of the next instruction, or information essential to the proper execution of the operation, e.g., a command to shift a datum within a machine register.; 機器指令的一部分,由表示要執(zhí)行的操 作的代碼組成。指令的其余部分可以是操作數(shù)地址,也可能包括下一個指令的地址,或是 對正確執(zhí)行操作來說十分重要的信息,例如使機器寄存器內(nèi)數(shù)據(jù)移位的一個指令。