Breadboard Computer: ALU and Register Demo

What you're seeing in this video is the A register (shown by the middle row of red lights) is set to 1 while the B register (lower row of red lights) is set to read from the bus (upper right row of red lights). Meanwhile, the ALU (the board in between represented by green lights) is set to add the values in A and B and feed the result to the bus. What ends up happening is the value in B counts up by one each clock cycle.