Tech Briefs

A package of software has been developed to execute a raw binary image of the space shuttle flight software for simulation of the computational effects of operation of space shuttle avionics. This software can be run on inexpensive computer workstations. Heretofore, it was necessary to use real flight computers to perform such tests and simulations.

A High-Level Schematic indicates the arrangement. (Note: CPU = central processing unit, IOP =input/output processor, ISP= information sharing protocol, PCMMU = pulse code modulation masterunit, MCDS = multifunction CRT display system, MDMs = multiplexer/demultiplexers, FC = flight critical,OC = operational instrumentation, and UI = user interface.)
The package includes a program that emulates the space shuttle orbiter general- purpose computer (see figure) [consisting of a central processing unit (CPU), input/output processor (IOP), master sequence controller, and bus-control elements]; an emulator of the orbiter display electronics unit and models of the associated cathode-ray tubes, keyboards, and switch controls; computational models of the data-bus network; computational models of the multiplexer-demultiplexer components; an emulation of the pulsecode modulation master unit; an emulation of the payload data interleaver; a model of the master timing unit; a model of the mass memory unit; and a software component that ensures compatibility of telemetry and command services between the simulated space shuttle avionics and a mission control center. The software package is portable to several host platforms.

This program was written by Scott Arnold, Bill Askew, Matthew R. Barry, Agnes Leigh, Scott Mermelstein, James Owens, Dan Payne, Jim Pemble, John Sollinger, Hiram Thompson, James C. Thompson, Patrick Walter, David Brummel and Steven P. Weismuller of United Space Alliance, LLC; and Ron Aadsen, Keith Hurley, and Chris Ruhle of Raytheon Co. for Johnson Space Center.

This Brief includes a Technical Support Package (TSP).

Space-Shuttle Emulator Software (reference MSC-23289-1) is currently available for download from the TSP library.

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