Way back in 1980, well before Nintendo manufactured their Famicom (or NES) system, they produced a series of devices called the Game & Watch systems. Each Game & Watch system had a single simple game on it, usually starring the brand mascot, Mr. Game & Watch.
The Game & Watch systems were designed after Nintendo designer, Gunpei Yokoi (1941 – 1997), spotted someone fiddling with a calculator aboard a train. This inspired Yokoi to design the Game & Watch concept, and the systems themselves were built using calculator technology.
Similar to how calculators display numbers using seven segments, the Game & Watch, too, displayed its graphics using separate components. 72 segments were possible in all, increased from the 56 segments possible on a calculator (a maximum of 8 digits comprised of 7 segments each).
Unlike more advanced games that were created later, Game & Watch games were created and tested using large crafted models the size of an A4 size piece of paper. Artwork for the games would be cut out of pieces of acrylic plastic and placed on a circuit board with tiny bulbs on them to emulate the screen of the digital game.
As Game & Watch technology advanced over the years, it ultimately resulted in Nintendo’s very first dual-screen handheld, which ran a port of the 1982 Donkey Kong arcade game.
You can read more about the development of the Game & Watch series in yet another fascinating Iwata Asks session with the original developers of the systems.