
Judging by your .sig you are trying to make some kind of game cartridge.
Information of how to build an EEPROM cartidge for the vectrex is available
via anonymous ftp at 'csus.edu'.

Since you've chosen the 27C512 you are probably trying to make a 'multicart'.
To do this simply:
1. Load the game images into the EEPROM at $2000, $4000, etc. (Your EEPROM
burner software may allow this or you will have to assemble the images into
one file yourself with suitable gaps.)
2. Wire up the cartridge with the lower address bits going to the game
console, and the high bits going to switches to choose between games.

To directly answer your question above, the pin that 'kicks up the address'
is simply another address line.