TL32 Datasheet, PDF (19/31 Pages) List of Unclassifed Manufacturers – Real Time System Testing MIT 16.070 Lecture 32

Fault Tolerance - Redundant Processors
Who needs 4 computers and a backup? The Space Shuttle
• On ascent and landing/entry the Space Shuttle uses 4 identical
computers and one backup. Why? A 1/2 second glitch in the
guidance, navigation & control software will cause the shuttle to spin
out of control.
• During rendez-vous and docking, 2 computers are used
• On orbit, only one computer is necessary
• In all cases, the backup computer is always available and runs a
different set of software than the other 4, a technique known as N-
version programming.
hperry
5/4/01