Comment by BitterPanda

I remember I tried to make a modular full-bit adder with NPN transistors, diodes and resistors. I was a bit foolish expecting NPN transistors to act as simple switches and I was in way over my head. But I learned a lot, since I went from this is a logic gate to can we build this as a circuit to holy f*ck this is actually how people did it. A very interesting project