Machine language

 The only programming language that can be interpreted and executed by the CPU is machine language. A machine language program is a sequence of instructions that represent the operation of one unit of the CPU. Each instruction is represented by an integer for easy and high-speed interpretation / execution by the CPU. When a machine language program is stored in the main storage device (ROM or RAM) in advance and the start address is given to the program counter (: A storage device in the CPU that holds the address where the next instruction to be executed by the CPU is stored), the CPU fetches instructions one by one from the main storage device and executes them.