Q. I want to port Python to a new platform.  How do I begin?

A. I guess the two things to start with is to familiarize yourself

with are the development system for your target platform and the

generic build process for Python.  Make sure you can compile and run a

simple hello-world program on your target platform.  Make sure you can

compile and run the Python interpreter on a platform to which it has

already been ported (preferably Unix, but Mac or Windows will do,

too).

I also would never start something like this without at least

medium-level understanding of your target platform (i.e. how it is

generally used, how to write platform specific apps etc.) and Python

(or else you'll never know how to test the results).

The build process for Python, in particular the Makefiles in the

source distribution, will give you a hint on which files to compile

for Python.  Not all source files are relevant -- some are platform

specific, others are only used in emergencies (e.g. getopt.c).  The

Makefiles tell the story.

You'll also need a pyconfig.h file tailored for your platform.  You can

start with pyconfig.h.in, read the comments and turn on definitions that

apply to your platform.

And you'll need a config.c file, which lists the built-in modules you

support.  Start with Modules/config.c.in.

Finally, you'll run into some things that aren't supported on your

target platform.  Forget about the posix module for now -- simply take 

it out of the config.c file.

Bang on it until you get a >>> prompt.  (You may have to disable the

importing of "site.py" and "exceptions.py" by passing -X and -S

options.

Then bang on it until it executes very simple Python statements.

Now bang on it some more.  At some point you'll want to use the os

module; this is the time to start thinking about what to to with the

posix module.  It's okay to simply #ifdef out those functions that

cause problems; the remaining ones will be quite useful.