So, here you see the complete ALU result register. It is a 16 bit register. The board with the 17 black relays is the storage board, 16 relays to store the 16 bits (the relays are holding themself active when switched on), one relay to switch off VCC to clear all 16 storage relays. The two other boards are used as an input enable board from the ALU or as an output enable board to the databus...