There's also an interesting book "A model implementation of standard Pascal" - not by Wirth - that implements an ISO Standard Pascal compiler in Standard Pascal, written as a "literate program" with copious descriptions of every single aspect. Basically, the entire book is one large program in which non-code is interspersed as very long multiline comments.
compiler.pas can be compiled with a modern Pascal compiler, but the resulting compiler cannot compile itself. I don't know if that's caused by a transcription error, a bug in the modern compiler or a bug in the Model Implementation.
I would love it if somebody gets this working. I don't think I myself will continue with this project.
I couldn't find it available for download anywhere, but Internet Archive has a version of it in the library that can be checked out for free: https://archive.org/details/modelimplementat0000wels/page/n9...