Hello and welcome to a.org =).
It's difficult to say if that missing leg is due to design or damage. The actual chip is a GAL, a kind of programmable chip which could be doing any number of functions. Most likely it performs some kind of custom glue logic function between the different chips on the board. I guess the only way to make sure is to try and find someone who has a similar CPU board and see if the leg is snapped off too.
(
http://en.wikipedia.org/wiki/Generic_array_logic ).
-edit-
Just spotted the soldered wire bridges in the background, maybe something funky is going on with this board...
