What is machine code? Definition and examples

Machine Code is a computer programming language comprising hexadecimal or binary instructions that computers can respond to directly. Machine code is written in a machine language. Therefore, a machine, i.e., a computer, can execute it without any translation or conversion.

Machine code operates at the core of computing, forming the fundamental instructions that drive both simple and complex operations within the system’s hardware.

We also refer to it as ‘machine language.’ We call the instructions that exist in machine code machine instructions.

Most shrink-wrapped or commercial software today is available in machine code. If users discover a bug or any kind of defect, they cannot make corrections. They cannot do anything because the software is not in human-readable programming language code.

We refer to all the instructions and codes (programs) within a computer as software. Without software, a computer would be unusable, i.e., it wouldn’t be able to do anything.

In machine code, each instruction causes the computer’s CPU to perform a very specific task, such as a store, jump, or load. CPU stands for central processing unit.

Machine code
Machine code consists of strings of ones and zeros.

Machine code – a numerical language

Machine code is the most basic kind of computer language—it’s made up of numbers only and is designed to run as fast as possible on a computer’s hardware. It’s the lowest-level language a computer understands, and it’s closely tied to how the computer’s physical parts work.

While you can write programs in machine code, it’s extremely difficult and time-consuming because you have to manually handle every tiny detail, like bits, addresses, and numbers.

That’s why programmers rarely write directly in machine code today. It’s mostly used for special situations, like debugging deep technical issues, fixing a program directly, or studying how compiled programs work.

The source code of every human-readable programming language must ultimately be translated into machine language by an interpreter or compiler. This is because computer hardware only understands long sequences or zeros and ones, i.e., binary code.

machine code - discovering a defect
If the user discovers a defect or bug there is nothing he or she can do to correct it. The programming language code is not human-readable.

Each CPU has its own unique machine language

The CPU of each computer has its own specific machine language. The processor reads instructions and handles them. They tell the CPU what to do (simple tasks).

The instructions consist of a certain number of bits. In an eight-bit instruction, for example, the first 4-bit part tells the processor what to do, while the second 4-bit part tells it what data to use. We call the first and second 4-bit parts the opcode and the operand respectively.

According to TechTarget:

Depending upon the processor, a computer’s instruction sets may all be the same length, or they may vary, depending upon the specific instruction.”

“The architecture of the particular processor determines how instructions are patterned. The execution of instructions is controlled by firmware or the CPU’s internal wiring.”


In an article in the Duke Law Journal, Pamela Samuelson wrote about machine code. It is so unreadable that the US Copyright Office cannot identify whether a specific encoded program is an original work of authorship.

The US Copyright Office does, however, allow for copyright registration of computer programs.

If you are able to decompile the program’s machine code so that humans can read it, your copyright application is more likely to be successful.

The intricacy of machine code necessitates specialized tools for debugging, which can decode the binary sequences into more comprehensible forms for programmers.