Building micropython for FreeDOS

FreeDOS build based on unix build and use djgpp as cross-compiler. Build process tested with linux ubuntu 14.04, but should work fine with other *nix operating systems. Since resulting micropython binary is bigger than DOS can hold, DOS extender should be used. This tutorial is based on CWSDPMI DOS extender and awesome build-djgpp.

1. Building djgpp via build-djgpp project.

   git clone https://github.com/andrewwutw/build-djgpp
   cd build-djgpp
   DJGPP_PREFIX=path/to/djgpp source build-djgpp.sh 5.3.0
   

   You probably will need to view build-djgpp readme for prereqs and version number.

2. Building micropython.

   git clone https://github.com/micropython/micropython
   cd micropython/unix
   PATH=path/to/djgpp/bin:$PATH make freedos    
   

3. Extending with dos extender (CWSDPMI).

   path/to/djgpp/i586-pc-msdosdjgpp/bin/exe2coff micropython_freedos.exe
   cat CWSDSTUB.EXE micropython_freedos > upython.exe
   

You can change extender options for upython.exe with CWSPARAM.EXE. CWSDPMI binaries are available at micropython-freedos ad-hoc module repo since official site is down sometimes.