What are the commonly used commands in the run?

In the case of a computer, for example, instructions are issued by a computer program. A computer program is a collection of computer instructions that will be executed one by one when the program is executed.

Computer (computer), commonly known as computer, is a modern electronic computer used for high-speed calculation, which can perform numerical calculations, logical calculations, and also has the function of storage and memory. It is a modern intelligent electronic device that can operate according to the program and process massive amounts of data automatically and at high speed. A computer that consists of a hardware system and a software system without any software installed is called bare metal.

It can be divided into five categories: supercomputers, industrial control computers, network computers, personal computers, and embedded computers, and the more advanced computers include biological computers, photonic computers, quantum computers, etc.

Inventor of the computer John von Neumann. The computer is one of the most advanced scientific and technological inventions of the 20th century, which has had an extremely important impact on human production and social activities, and has developed rapidly with strong vitality. Its application has expanded from the initial military scientific research and application to all fields of society, and has formed a huge computer industry, which has led to the progress of global technology, which has triggered profound social changes, and computers have spread all over ordinary schools, enterprises and institutions, and have entered the homes of ordinary people, becoming an indispensable tool in the information society.

A privileged directive is an instruction with special authority. These instructions are only used on the operating system or other system software and are generally not provided directly to the user.

Since this type of directive has the most permissions, if used incorrectly, it will cause the entire system to crash. For example, you can clear memory, set clocks, allocate system resources, modify virtual segment tables and page tables, and modify user access permissions.

Generally speaking, privileged instructions are not available or required in single-user, single-task computers, but are indispensable in multi-user, multi-task computer systems. It is mainly used for the allocation and management of system resources, including changing the working mode of the system, detecting user access rights, modifying segment tables, page tables and completing tasks for virtual storage management, etc.

This starts with the privilege level of the CPU instruction system (the commands used to control the various functions performed by the CPU). Out of all the instructions in the CPU, there are some instructions that are very dangerous and if misused, will cause the entire system to collapse. For example:

Clear memory, set clocks, etc. If all programs can use these instructions, then it wouldn't be surprising that your system crashes n times a day. Therefore, the CPU divides the instructions into privileged and non-privileged instructions, and for those dangerous instructions, only the operating system and its related modules are allowed to use, and ordinary applications can only use those instructions that will not cause disaster.

Figuratively speaking, privileged directives are those that are not suitable for children, while non-privileged directives are suitable for all ages.

An instruction is a command that instructs a computer to perform a certain action, and it consists of a string of binary digits.

Opcode: Indicates the type or nature of the operation to be completed by the command, such as fetching numbers, doing addition, or outputting data.

Macros: A macro is a type of pseudo-instruction in an assembly language program.

It is formatted:

Macro name ] macro [formal parameter].

**Segment. ...endm

"Formal parameters" are used, which refer to macros and are replaced by some given name or value (real parameters). The use of formal parameters gives macros a lot of flexibility.

Macro call format.

Macro name ] Actual Argument].

The real parameter item will replace the formal parameter in the macro accordingly. If the formal parameter is a label, the argument should also be a label in the macro call, and the argument must be unique. If the macro definition has its own designator, the assembler automatically turns the designator into a unique designator when the macro is called.

Pseudo-instructions: Pseudo-instructions (pseudo-operations) are not executed by the computer during the running of the program like machine instructions, but are operations that are processed by the assembler during the assembly of the assembler to the source program. It can perform functions such as processor selection, defining program modes, defining data, allocating storage areas, indicating the end of programs, and more. Pseudo-directives are not generated at compile time** Pseudo-directives do not exist after compilation.