Pascal (ISO 7185:1983)

Compared to C, the original Pascal language had some rather idiosyncratic restrictions, which made it difficult to write programs in.

OS-9 Pascal

OS-9 Pascal is a very thorough implementation of the language according to ISO Standard 7185.1 level 0. It has a few extensions: CASE statements can have an OTHERWISE option; bit-by-bit Boolean operators are included ('&', '!' and '#').