unportable's Usage Examples:

optimized for machines with 64 byte cache lines, making them essentially unportable without a significant rewrite.

The program code itself can also contain unportable things, like the paths of include files.

operating systems use different command-line interpreters this can lead to unportable makefiles.

so much that the Scheme Steering Committee calls it "the world's most unportable programming language" and "a family of dialects" rather than a single.

These libraries reduce the need to use unportable operating system features and third-party libraries (which might not always.

kernels, the UNSW kernels (written in a mixture of assembly and C) were unportable and each implemented from scratch.

used on many different types of computer systems, and which methods were unportable.

III included machine-dependent features that made code written in it unportable from machine to machine.