Hence I believe it is an ASIC. Its audio sounds very similar to the 1982 version when turned on, but the (much cheaper than 1977/1979) switches need some repair (carbon coated conductive paper disks are falling off the backs of the switches; the 1977/1979 version has metal conductive bell-shaped contacts attached to the switch shafts instead which are much harder to damage or fall off, but are also clearly more expensive to produce).
I assume this whole thing was done as a cost reduction measure, possibly as a buildup to lower the retail price of electronic battleship sometime in 1980.
"When life gives you zombies... *CHA-CHIK!* ...you make zombie-ade!"