Binary-code compatibility

Binary-code compatibility (binary compatible or object-code-compatible) is a property of computer systems meaning that they can run the same executable code, typically machine code for a general-purpose computer CPU. Source-code compatibility, on the other hand, means that recompilation or interpretation is necessary.

For a compiled program on a general operating system, binary compatibility often implies that not only the CPUs (instruction sets) of the two computers are binary compatible, but also that interfaces and behaviours of the operating system and APIs, and the ABIs corresponding to those APIs, are sufficiently equal, i.e. "compatible".

A term like backward-compatible usually implies object-code compatibility. This means that newer computer hardware and/or software has (practically) every feature of the old, plus additional capabilities or performance. Older executable code will thus run unchanged on the newer product. For a compiled program running directly on a CPU under an OS, a "binary compatible operating system" primarily means application binary interface (ABI) compatibility with another system. However, it also often implies that APIs that the application depends on, directly or indirectly (such as the Windows API, for example), are sufficiently similar. Hardware (besides the CPU, such as for graphics) and peripherals that an application accesses may also be a factor for full compatibility, although many hardware differences are hidden by modern APIs (often partly supplied by the OS itself and partly by specific device drivers).

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