The command for a computer to perform an operation is called

The command that a computer performs an operation is called an instruction, which is the smallest functional unit of a computer. Instructions are instructions from superiors to petitions from subordinates. In other words, it is the code that tells the computer to do special operations. Such as data transmission instruction, arithmetic operation instruction, bit operation instruction, program flow control instruction, string operation instruction and processor control instruction.

Usually, an instruction includes two aspects: operation code and operand. The operation code determines the operation to be completed, and the operand refers to the data involved in the operation and its cell address. In the computer, the operation requirements and operand addresses are represented by binary numbers, which are called operation codes and address codes respectively, and the whole instruction is stored in the memory in the form of binary codes.

Instruction execution program

The sequential execution of instructions will complete the execution of the program, so it is necessary to understand the execution process of instructions. The first is to obtain instructions and analyze instructions. According to the order specified by the program, the currently executed instructions are taken out of the memory and sent to the instruction register of the controller, and the taken instructions are analyzed, that is, what operation the computer should perform is determined according to the operation code in the instructions.

The second is to execute instructions. According to the result of instruction analysis, the controller sends out a series of control potentials needed to complete the operation, so as to command the relevant parts of the computer to complete the operation and prepare for the next instruction. Each computer has its own specific instruction system, and the instruction content and format are different.