Although Radio Shack had the color computer, we don’t think they had that in mind. [Pepepépepe] has coloring book pages and simple rules that let you simulate logic circuits using a pencil. The downloadable ‘zine contains hand-written instructions and several examples.
Keep in mind this is a computer in the same way old logic kits from the 1960s were computers. These are really demonstrations of digital logic circuits. To make the “computers” work, you choose two colors, one for a square and the other for a circle. You color the paths until you reach a “nory”. The nory, which looks suspiciously like a slingshot with eyes, has a special rule. If both branches of the nory have your circle color on them, the output of the nory will be the square color. Otherwise, the color that stands out is the color of the circle.
Obviously, this rule generates a NOR gate where the color of the circle is a zero and the color of the square is one. Because colors flow along paths, you can draw display elements, including 7-segment displays, and make them work.
There are a few more rules to learn, and you can build a computer that even has a gamepad. No kidding. Is it practical? Of course not. But it could be a fun introduction to digital logic for a smart kid, and who knows where it will lead?
It would be fun to recreate some of the old Geniac “computers” like this. If you like paper computers, there is CARDIAC (you can even simulate this paper computer on an FPGA).