The limited cross-linker for MACRO11 PDP-11 assembler (gzipped sources, 2K), it can't be directly used from Microsoft Windows — see note.
Notepad+4, БK0011 edition
Reduced Basic cross-compiler
32/64-bit Xlife ported to 8/16-bit world!
The number π calculator is here (the sources are included). The archive contains versions for the БK0010, БK0011, RT-11, and RSX-11.