nonportable

Nonportable is an adjective used in computing to describe software, code, data, or systems that cannot be easily moved to, or executed on, different hardware platforms, operating systems, or environments without significant modification. It is the opposite of portable or cross-platform software and is often cited in discussions of software maintenance and reuse.

Causes of nonportability include reliance on platform-specific APIs or libraries, nonstandard language extensions, architecture differences (such as word size, endianness, or pointer representations), and binary interfaces or compiler behavior that do not translate across environments. Nonportable data formats or file layouts that encode hardware assumptions can also become a barrier to transfer.

Common examples include applications that call Windows-only APIs (Win32), use assembly language or inline assembly tied to a single processor, or depend on proprietary features of a given operating system. Data can be nonportable when written in a binary form that presumes a particular endianness or integer size, or when it embeds absolute file paths or environment specifics.

Nonportability has implications for maintenance, distribution, and reuse. It can lead to vendor lock-in, duplicated effort, and higher cost when porting software to new platforms. In some contexts, nonportability is intentional for reasons of performance, access to specialized hardware, or regulatory requirements.

Strategies to improve portability include coding to standards, using cross-platform libraries and runtimes, isolating platform-dependent code behind abstract interfaces, and employing build configurations that adapt to target environments. Data should be serialized in portable formats, with explicit handling of endianness and data sizes. Regular testing on all supported platforms and documentation of platform assumptions further reduce nonportability.

See also: portability, cross-platform development.