The latest UltraSPARC/sup TM/ III generation of servers from Sun Microsystems makes extensive use of BIST and other DFT techniques to help improve test coverage and reduce test time during power-on self test. This paper is a case study which examines a number of different BIST techniques used in the Sun Fire/sup TM/ Midframe servers, and shows how they were combined to improve diagnosis of faults and overall system availability. Specific DFT techniques which are discussed include ASIC-based internal and external memory BIST, ASIC logic BIST, microprocessor-controlled interconnect test using IEEE 1149.1 boundary scan, and at-speed interconnect BIST tests across system buses.
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