John Trudeau, a fellow designer at Mylstar, provided us the following information:

'Jacks to Open' served as the test platform for the first alphanumeric displays, although they first appeared in production on Premier's 1985 'Chicago Cubs "Triple Play"'. We actually made ten complete 'Jack to Open' games with the alphanumeric display and a new backglass (having new art to fit the openings for the new digits). There was some management concern that it wouldn't make any difference in the cashbox. That turned out to be undetermined, since there really was no way to tell how much the game would have made without it, at the same location. But we did get some positive feedback because of the initials-entering capability it now had. And players in general liked the displayed messages too.

ipdb.org hosted at pair.com