Tank

Tank
Developer: Kee Games Publishers: Kee Games (US), Nakamura Seisakusho[1] (JP) Platform: Arcade (discrete/TTL) Released in JP: September 1975[2] Released in US: November 5, 1974 This game has unused graphics.

Tank is one of the first known arcade games to use solid-state ROM (in this case, a tiny 2KB Mostek MK28000 chip) to store data. It's also the oldest game on this site...at least until someone manages to find something in Gran Trak 10.

Since Tank II is essentially identical to Tank but with a different playfield, the information below applies to that as well.

Unused Graphics

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.

(Source: Original TCRF research)