Interesting thing this person has thought of:
I think the 4-digit code is year/week. 9141FP would be 1991, week 41. Stuff beyond that probably shows which chip fab made it (assuming the company has several). As far as programmable roms go, I mean.
If this is true (it does seem to work for a few games I checked), then this means the game I'm trying to identify was released in or before 1989 (possibly 1990). That narrows it down a little bit more.
EDIT: Well whaddya know? Galaxy Force was from 1989... Then again, so was Chase HQ, Casino Games and Wonder Boy III.