Pascal implementation: The P4 Compiler

The p-system was a series of model compilers for the original language Pascal, and constituted a compiler porting "kit" produced by Zurich, designed to propagate the Pascal language quickly. P4 was the last such version of the compiler, and the authors go into great detail over the workings of P4. It remains an essential reference for the compiler, which is still used as an example compiler in compiler writing courses. Note that this is not related to the Borland "Pascal" language, which bears little resemblance to the original Pascal language.