A Unisonic Tournament 100 circa 1976 -- not working -- and a Coleco/Radofin Tele-Sports Mini, circa 1978 -- working fine, with original box. Both are most likely based on General Instrument's infamous "Pong on a chip" IC.

Pong was the first hugely successful video game, popular enough in the '70s to support its own entire genre of home consoles. Even after cartridge-based systems like the Atari 2600 and Intellivision took over the marketplace, dedicated pong consoles remained popular until the early '80s -- adding color and additional game variations -- as a low-priced alternative.