Pascal (ISO 7185:1983)

Compared to C, the original Pascal language had some rather idiosyncratic restrictions, which made it difficult to write real programs in. It was clearly intended to be for learning how to program.

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 '#').