Program and data files in the Unified Control Modules (UCMs) of the Operational Television system at Kennedy Space Center are updated rapidly and automatically in a scheme that exploits unique features of the UCM design. Each UCM includes a VersaModule Eurocard (VME) chassis, in which are installed several singleboard central processing units (CPUs) and a board that holds 8MB of flash electrically erasable, programmable read-only memory that is accessible to all the CPUs via the VMEbus. This flash memory can be erased and reprogrammed without removing the memory circuitry from the UCM. The CPUs utilize the VxWorks real-time operating system, which provides, among other things, interprocessor communication via the VME backplane, support for networking, and support for MS-DOS file systems. A VxWorks driver program creates an MSDOS file system in the flash memory and provides for access to, and manipulation of, the files. Each time the UCM is rebooted, one CPU, designated the main CPU first determines whether a designated host computer is available in a network to which the UCM is connected. If so, the main CPU obtains a list, stored in the host computer, of files that should be in the flash memory. If it finds that the modification date and time of a given file in the host differs from those in the flash memory or if the file does not exist in flash memory, then the file is copied to the flash memory. Once flash-memory files have been thus updated, the main CPU signals the other CPUs to complete their booting and gain access to the files in the flash memory card via the VMEbus.

This work was done by Charles H. Chapman of Dynacs Engineering Co., Inc., for Kennedy Space Center. For further information regarding this technology, contact Mr. Charles Chapman at (321) 232-8141 or via e-mail at This email address is being protected from spambots. You need JavaScript enabled to view it..

NASA Tech Briefs Magazine

This article first appeared in the October, 2002 issue of NASA Tech Briefs Magazine.

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