[plt-scheme] plt scheme source?

Hi all, i downloaded the plt scheme source for mac a few days ago, and
i have been trying to make sense of how plt scheme works. In order to
improve understand how a real language is designed and implemented,
and to improve my scheme/c knowledge.

I still can't really tell where i should start diving in first, been
trying to make sense of what seems to be the basic file of the entire
thing (its included one way or another in almost every other file),
src/mzscheme/include/scheme.h. However, what i would like most to know
is how the scheme primitives are implemented, such as lambda and
others, in c. Perhaps it will be more productive for me to dive in
top-down instead of bottom up and understand how basic stuff gets
translated into c.

Any rough pointers in those areas would be greatly appreciated!

Thanks a lot!

Jason
-- 
"It's a wonderful world hobbes ol' buddy, let's go explorin'!" -
Calvin in "Calvin and Hobbes"