The missile is programmed with launch codes through the Permutation Plug, a plug that holds the 48-bit code. With great ritual, an armed officer plugged it into the socket below. The launch code also depended on values on disk, so each Launch Control Center had a unique code for each missile. 19/N
A launch normally requires launch orders from two separate Launch Control Centers. But a single surviving Launch Control Center could launch the missiles, unless vetoed before a timeout. A complicated state machine managed the launch process. 20/N