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[DPRG] Shuttle computer question

Subject: [DPRG] Shuttle computer question
From: gibbonscl cjg at computer.org
Date: Sat Feb 8 14:36:00 CST 2003

> I've heard that the processors on the space shuttles are or were 386 or 486 processors?
> Can't seem to find anything to confirm this. DOes anyone here know?

"Computers Driving Shuttle Are to Be Included in Inquiry"
New York Times (02/07/03) P. A22; Lohr, Steve 
a.. The on-board computers were driving the Columbia space shuttle when it descended into the earth's atmosphere Saturday, Feb. 1, and ordered the ship to steer right slightly in compensation for drag registered on the left side. The shuttle's computer are still of the same basic design as when they were developed by IBM in the 1970s, but the software has never been faulted for safety reasons and is considered one of the best examples of robust code. Although relatively weak in processing power, the on-board computers, named AP-101, are extremely efficient at calculating and adjusting to readings coming in from sensors all over the ship, and work using a specialized programming language called high-order assembly language/shuttle (HAL/S). The programming on the shuttle is rated Level 5 by Carnegie Mellon University's Software Engineering Institute for its reliability and development process, a rating achieved by only a few projects worldwide. Before the crash, NASA was considering replacing the aged systems with newer versions for budgetary reasons, since finding component replacements was increasingly difficult. However, new shuttle software could introduce bugs because the software and hardware were designed in tandem. Europe's Ariane 5 rocket blew up in 1996 because of a small software error that came from porting code from the previous Ariane 4 rocket without adequately testing it in the new system. Although no one has yet blamed the AP-101 for the shuttle disaster, at least one engineer has said the computer may not have had all the data needed to do its job. Richard Doherty, a member of the investigative committee for the space shuttle Challenger, says that NASA officials could have sent updates to the AP-101 to account for damage to the left wing during lift-off, which may have caused extra drag during the descent.
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