Instructions are instructions and commands to command the work of the machine, and the program is a series of instructions arranged in a certain order, the process of executing the program is the working process of the computer.
Controllers rely on instructions to command the machine, and people express their intentions with instructions and give them to the controller for execution. A computer can perform a variety of different instructions of the whole, called the computer's command system, the first computer has its own specific instruction system, its directive content and format are different.
Usually one instruction consists of two aspects: one refers to what the machine does, that is, the operating requirements, the other is the address of the operation number in the memory or general register group, that is, the address of the operand.
In a computer, the operational requirements and operand addresses are represented by binary digits, called opcode and address codes, and the entire instruction is stored in binary coded form in memory.
The type and number of instructions are related to the specific model, which is not detailed here, please refer to the specific machine information manual.
The sequential execution of the instruction will complete the execution of the program, thus it is necessary to understand the execution of the instruction. The first is to take instructions and analysis instructions. According to the order of the program, take out the current executing instruction from the internal memory and send it to the controller's instruction register to analyze the instructions, that is, according to the operation code in the instructions to determine what the computer should do.
followed by the execution of instructions. According to the instruction analysis result, the controller emits a series of control potentials required to complete the operation, in order to direct the computer related parts to complete this operation, and also to prepare for the removal of an instruction.
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