Target writers documentation is a document intended to contain the information needed to write support for a new target.
How-it-works -- information on how the compilation process works.
Building -- how to build PCC for your platform.
Supported-Platforms -- list of supported platforms.
Common-Problems -- solving some common problems.
Cross-Compiler -- examples of using pcc as a cross compiler.
Cross-Compile -- how to cross-compile pcc for a different host.
The internals pages document the design and implementation of ccom (pcc's compiler).
Unicode for the PCC C99 Compiler written by Eric Olson describes the unicode support in PCC.