The machine code, Machine Language, is the elementary programming language that is understood by a processor and can be processed by it. Each processor has its own machine code. In thehierarchy ofprogramming languages the machine code occupies the lowest level and is also called programming language of the first generation( 1G).
Machine code can be coded in the dual system but also in other number systems such as the hexadecimal system or the octal system. A machine code written in the dual system is a long bit combination of zeros and ones. Each machine instruction that a processor can process is assigned a specific numeric code. These can be instructions for arithmetic and logical operations, instructions for shift registers, for interrupts or jump instructions. The instructions often consist of 8 bits, where the first 4 bits represent the machine instruction and the second 4 bits represent the operand.
Each processor architecture has its own instruction structure. The instructions executed are controlled by the firmware. Programs written in assembler or in another programming language must first be translated into the used machine code via an assembler, compiler or interpreter.