I was looking for something else completely last night on the Web, and
found this:

http://www-cgi.cs.cmu.edu/afs/cs.cmu.edu/user/bsy/www/ftp.html#code

look in particular at

ftp://play.trust.cs.cmu.edu/usr/bsy/pub/save_world.tar.Z

I make no claim about any of it - just that the description seems to fit
what you asked for.

Erik Fair