UNIX: a portable operating system?

The use of top-down design methods and high-level languages in producing portable applications software is well established. By applying the same principles at the systems programming level, portability can be extended to the operating system itself.Although the Unix operating system was developed for a specific computer (the DEC PDPll), its concise and elegant design and the careful selection of 'primitives' which it provides make it an ideal candidate for portability. This paper describes the experience of adapting Unix to an Interdata 7/32.