What are the two categories of instructions in the application?

The instructions in the application program can be divided into two categories: the instruction set of the central processor and those used to request specific services from the operating system. An instruction is composed of one or more bytes, including an opcode field, one or more fields related to the operand address, and some status words and feature codes that represent the machine status.

The operating environment of this tutorial: Windows 10 system, Dell G3 computer.

Theoretically, the instructions in the application can be divided into two categories: the instruction set of the central processing unit (CPU) and the one used to request specific services from the operating system.

Central Processing Unit (CPU, Central Processing Unit) is a very large-scale integrated circuit, which is the computing core (Core) and control core (Control Unit) of a computer; its main functions are Interpret computer instructions and process data in computer software. The processing flow of CPU operation instructions is roughly divided into several steps: instruction fetch, decoding, execution, memory access, and write back.

Computer instructions are instructions and commands that direct the work of the machine. A program is a series of instructions arranged in a certain order. The process of executing the program is the working process of the computer.

The command sent by the computer program to the computer processor is the "instruction". The lowest level instruction is a string of 0s and 1s, indicating that an entity job operation is to be run (such as "Add"). Depending on the instruction type, a specific area of ​​storage called a "register" contains data or data storage locations that can be used to recall the instruction.

Composition form:

Instruction is a command that instructs the computer to perform a certain operation. It consists of a string of binary numbers. An instruction usually consists of two parts: operation code and address code.

Operation code: Indicates the type or nature of the operation to be completed by the instruction, such as fetching numbers, adding, or outputting data, etc.

Address code: Indicates the content of the operation object or the address of the storage unit where it is located.

Execution program of instructions: The sequential execution of

instructions will complete the execution of the program, so it is necessary to understand the execution process of the instructions. The first is to fetch and analyze instructions. According to the order specified by the program, the currently executed instructions are fetched from the internal memory and sent to the instruction register of the controller. The fetched instructions are analyzed, that is, what operations the computer should perform are determined based on the operation codes in the instructions.

The second is to execute the instructions. According to the instruction analysis results, the controller issues a series of control potentials required to complete the operation in order to direct the relevant components of the computer to complete the operation. At the same time, it is also ready to fetch an instruction.

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