Calculator using relays.
I made this circuit after watching this video. (https://youtube.com/watch?v=PX_aa7Tjtbg)
The placement of switches, displays, and circuits are the same as the originals.
However, The circuit diagram is not introduced, so it is my imagination.
I believe the encoder and adder/subtracter are the same as the original, but the register and decoder are different circuits.
Eight relays were left over from the original.
I do not know if this is because we omitted the signal runaround prevention circuit in the display circuit and made the circuit work only with LEDs that have a rectifying effect, or if it is an overflow detection circuit that is not introduced in the video.
