Appeal No. 2002-0374 Page 9
Application No. 08/599,227
setting a defect bit to prevent further use of the memory location.
Turning to Lucente (page 404) we find that Lucente discloses
that "[t]his device isolates hard errors in system memory by
writing a true and complement[ary] pattern to each system memory
location. Locations from an on-chip associative cache are then
mapped into the address space in place of the faulty locations.”
When a faulty system memory location is located during system
testing, its address is placed in the address tag of one cache
location. The location of the failed bit or bits is also stored.
All accesses calling for the faulty location will now be directed
to the replacement cache location the architecture of Lucente (page
408) is implemented in a Memory Reliability Enhancement Peripheral
(MREP) device. The MREP provides redundancy at a system level by
using its on-chip cache to replace failed words anywhere in the
memory system. In addition (id.) "[a]s each failed memory location
is detected, a cache location replaces it." Thus, from the
disclosure of Lucente, we find that Lucente replaces defective bits
by replacing them with a location in cache, and does not disclose
the provision of unmapped cache locations which can be used as
temporary cache without displacing or overwriting portions of the
memory.
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