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Unformatted text preview: 8 VLSI Test Principles and Architectures This formula is widely used in reliability engineering; for example, telephone sys- tems are required to have system availability of 0.9999 (simply called four nines ), while high-reliability systems may require seven nines or more. Testing is required to ensure system availability. This testing may be in the form of online testing or offline testing , or a combination of both. Online testing is performed concurrently with normal system operation in order to detect failures as quickly as possible. Offline testing requires that the system, or a portion of the system, be taken out of service in order to perform the test. As a result, offline testing is performed periodically, usually during low-demand periods of system operation. In many cases, when online testing detects a failure, offline test techniques are then used for diagnosis (location and identification) of the failing replaceable component to improve the subsequent repair time. When the system has beencomponent to improve the subsequent repair time....
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This note was uploaded on 05/16/2011 for the course ENGINEERIN mp108 taught by Professor Elbarki during the Spring '08 term at Alexandria University.
- Spring '08