Automatic eprom identification using pin A9

[tridentsx]

How does eprom programmers auto detects eproms ?
As I understand it by putting a higher voltage on pin A9, an ID can be read from the chip, but eproms comes in many packages and A9 can be on different places in the ZIF socket. Is there a way to see which pins has been connected to "guess" what type of package is inserted and that way "guess" what pin in the socket is A9?