Machine Code
TLDR: Machine code is the lowest-level representation of a computer program, consisting of binary instructions executed directly by a computer's CPU. Introduced in the early days of computing in the mid-20th century, machine code is generated from high-level programming languages or assembly language by compilers or assemblers. Each instruction in machine code corresponds to a specific operation, such as arithmetic, memory access, or control flow, that the processor can perform.
https://en.wikipedia.org/wiki/Machine_code
Machine code is hardware-specific, meaning the instructions are tailored to the architecture of a particular CPU, such as x86, ARM, or RISC. Unlike high-level programming languages, machine code lacks readability and portability, making it challenging for humans to write or debug directly. However, understanding machine code is crucial in certain domains, such as low-level debugging, embedded systems, and performance optimization, where precise control over hardware is required. Tools like disassemblers and hex editors aid in analyzing and modifying machine code.
https://www.gnu.org/software/binutils/
In modern software development, machine code is typically an intermediate product of compilation, with developers relying on high-level programming languages to write source code. However, it plays a vital role in ensuring that programs run efficiently on target hardware. For example, compilers optimize machine code to minimize instruction cycles and improve CPU utilization. Additionally, knowledge of machine code is indispensable in reverse engineering, allowing experts to analyze software behavior and security vulnerabilities.
https://docs.oracle.com/en/java/javase/20/troubleshooting/debugging-overview.html
- Snippet from Wikipedia: Machine code
In computer programming, machine code is computer code consisting of machine language instructions, which are used to control a computer's central processing unit (CPU). For conventional binary computers, machine code is the binary representation of a computer program that is actually read and interpreted by the computer. A program in machine code consists of a sequence of machine instructions (possibly interspersed with data).
Each machine code instruction causes the CPU to perform a specific task. Examples of such tasks include:
- Load a word from memory to a CPU register
- Execute an arithmetic logic unit (ALU) operation on one or more registers or memory locations
- Jump or skip to an instruction that is not the next one
In general, each architecture family (e.g., x86, ARM) has its own instruction set architecture (ISA), and hence its own specific machine code language. There are exceptions, such as the VAX architecture, which includes optional support of the PDP-11 instruction set; the IA-64 architecture, which includes optional support of the IA-32 instruction set; and the PowerPC 615 microprocessor, which can natively process both PowerPC and x86 instruction sets.
Machine code is a strictly numerical language, and it is the lowest-level interface to the CPU intended for a programmer. Assembly language provides a direct map between the numerical machine code and a human-readable mnemonic. In assembly, numerical opcodes and operands are replaced with mnemonics and labels. For example, the x86 architecture has available the 0x90 opcode; it is represented as NOP in the assembly source code. While it is possible to write programs directly in machine code, managing individual bits and calculating numerical addresses is tedious and error-prone. Therefore, programs are rarely written directly in machine code. However, an existing machine code program may be edited if the assembly source code is not available.
The majority of programs today are written in a high-level language. A high-level program may be translated into machine code by a compiler.