SPACE SHUTTLE MAIN COMPUTER. IBM AP101B GENERAL PURPOSE COMPUTER, MANUFACTURED 11 NOVEMBER 1988

SPACE SHUTTLE MAIN COMPUTER

IBM AP101B General Purpose Computer, manufactured by IBM Corp, 11 November, 1988

Metal outer case, 19 1/2 by 10 by 7 1/2 inches, with interior gold-plated electronics having a total weight of 54 pounds. Five data ports and an analog hour meter (reading 799 hours) located between dual hand brackets at the front. Side ID tag reads in part: "MFG by IBM Corp. Owego, NY for Rockwell Int. Space Division, CII, MC615-0001-0210, Contract No. NAS9-14000, Part No. 6247100-26, Serial No. 14, Date of MFG – 11/11/88, Model Type - Production." A paper label on upper side reads in part: “Item Name: Central Processing Unit. MFG. Name: International Business Machines. MFG. Model: FVC11. MFG. Ser.: 014. FSC: 7021. Condition Code: B4. Cost: 300,000.00.”

Development of the Space Shuttle flight General Purpose Computers (GPC) began in early 1972, and each Space Shuttle Orbiter was outfitted with five sets of AP101B General Purpose Computers (GPC). The GPC units consisted of two main components constructed as group unit, the Input Output Processor (IOP) and a Central Processing Unit (CPU). Four of these operated in synchronization for redundancy, while the fifth acted as a backup. The CPU controls access to the memory of the General-Purpose Computers and executed commands to vehicle systems, while the IOP formatted and transmitted commands to Space Shuttle systems, received and validated response data, and maintained the status of interfaces with the CPU and the other GPCs.