Whatever relay circuit I happen to make
I was going to make an ALU with my adder, my XOR/AND logic card (which I was still working on), and a ton of other relay-consuming parts. Then I did some research on how best to wire all these parts together and found a 1-bit, 9-relay, 128-function ALU.
Although many of these functions are useless or unknown, a 8-bit version would be many times more powerful than my ALU design, and probably use less than half of the relays.
For full details look here.
I decided to build the circuit.
Seems to work!
The eight switches tell the ALU which function to run. The two small switches on the right side of the breadboard are A and B inputs. Red LED is the result, small green LED in the left is the carry out.
I have built a relay adder before on a breadboard. It was a two bit adder just to play with my new relays.
I decided to make a more advanced, more permanent version.
The new one uses 8 relays: 2 for the first bit and 3 for each bit after. There are LEDs soldered in for the result and the carry bit from the sum of the least significant bits.
I decided not to use switches because I want to possibly use it in an ALU later on. The port on it is there to connect to some kind of ALU backplane.
I tested it by adding two and three. Since I didn't want to put switches in the test I wired the inputs of the adder directly to the power rails for two + three:
The wiring of the board is a bit crazy, but each stage is a bit better. The third stage has only two floating wires! XD
Next i think I'll work on an XOR/AND board.