Assembly language is a programming language that describes machine language instructions in a way that is easy for humans to understand (close to English). One line of the program written in assembly language corresponds roughly to one instruction of the opportunity program. A word representing a machine language instruction (integer) is called a mnemonic. The mnemonic depends on the CPU and the assembly language used. For example, the second mock of a machine language instruction to move data is “MOV” (The word “move” from English).
Since assembly language is not a machine language, a CPU cannot execute a program written in assembly language. A program written in assembly language is converted into a machine language program by an assembler, and the obtained machine language program is executed.
In assembly language, you can specify each action that the CPU performs. Therefore, it is suitable for creating a program for finely controlling the input / output device.