This game has unused graphics.
Tank is the first known arcade game to use solid-state ROM (in this case, a tiny 2KB Mostek MK28000 chip) to store data. As such, it's the earliest possible arcade game on this site and the oldest game on the site in general.
Since Tank II is essentially identical to Tank but with a different playfield, the information below can apply to that as well.
512 bytes of the aforementioned ROM are used to store score images, which range from 0 to 63. Given the starting position of the two tanks, the maximum game time of 120 seconds, and the long invulnerability period after each shot, a lot of images go unused.
|The Tank series|
|Arcade||Tank • Tank 8 • Ultra Tank|