dcn@ihlpm.ATT.COM (Dave Newkirk) (01/31/89)
I just read a short article in the January 1989 issue of IEEE Software magazine about changes in the ground software systems that support the US Space Shuttle program. It contains part of an interview with Jack Munson, the vice president and general manager of Unisys's Houston operations, which runs the ground-based software systems of the shuttle, including telemetry and simulators. The software contains 14 million lines of code (not counting the OS or compilers), which went through 3,800 requirements changes and 900 releases, three of which were major upgrades. The hardware systems were also updated from '70s technology to the '80s. In spite of all these changes, only one new bug was found during the Discovery mission last fall, a 30 second lapse in telemetry recording, which was traced to a requirements problem. There were other known non-critical bugs, averaging about 1,800 (or about 1 bug per 7700 lines) over time. -- Dave Newkirk, att!ihlpm!dcn