The series debuted on June 1, 1977 with the Color TV-Game 6 (カラー テレビゲーム6 Karā Terebi-Gēmu Roku). The Color TV-Game 6 was jointly developed with Mitsubishi Electronics. It contains six variations of Light Tennis (or Pong) including Tennis, Hockey and Volleyball; each one can be played in singles or doubles mode. The players control their paddles with dials attached directly to the machine. Additionally, as an alternative to the standard version, a white-colored C battery powered model of the Color TV-Game 6 was introduced. These white colored consoles had a limited run of only a few hundred units.
Source: Wikipedia, "Color TV-Game series", available under the CC-BY-SA License.