Engineering test unit of a Space Shuttle Orbiter Backup Flight Controller, measuring 5" x 15" x 7", with Autonetics label on top: "Des. P165A, Ser No. 94756-A02Y, Part No. 10021-507-21, Spec. MC615-0023-9004, Backup Flight Controller (ADL Prototype), Contr. NAS9-14000, Mfr Code 94756." The front has four ports, marked "J1" through "J4," and three sides are marked in ref: "Engrg. Test Only." The backup flight controller provided flight control in the event that one of the primary Shuttle Orbiter General Purpose Computers (GPC) failed. The backup controller (three carried on each Orbiter) was connected to an alternate GPC to assume flight management and control.
