Computer Instructions:  A digital system such as a processor or CPU accepts binary data as input, processes that data, and then provides output based on the instructions stored in the memory. The processor has an ALU to process the data, registers for temporary data transfer and the control unit manages the flow of instructions and data through the system. It requires the user to store the program (set of instructions) in memory. Format of the instruction When the execute command is given, the instruction from the memory is read into the instruction register (IR). The instruction is basically divided in two parts, the instruction code and the address part of the instruction.  Format of the instruction is given below: Instruction Code Address part of instruction Mode