One more computer chess request (unrotated [:-)])

[Bob Levinson]

A few weeks ago I posted a request to the net for a machine readable
chess library. This article is to note that nothing panned out. The
closest I got was an offer to give me machine readable computer
chess games. Not quite what I needed.
 
I have a new request/query:
    I would like to have code which takes a chess position, a chess move
(in algebraic or descriptive notation) and generates the next chess
position. Does anybody know where I might get this?
 
Along these lines: Is the source to the chess program on UNIX BSD4.2
available?
 
All help is much appreciated.
 
Thanks,
   Bob