The three registers each have a set and enable switch, the enable is the one with the switch. You don't need to switch the 1 to 0 just turn the switch on or off. The set is the other number. Here you do need to switch the number. The number at the way top is acting like Input from the computer. You can copy information from the computer input or from register to register. But remember to always keep at least 1 of the 4 switches on or else the power will be lost and information in the registers will be lost.
