Appeal No. 96-3359
Application 08/204,592
According to the examiner, it would have been obvious to
rearrange Arnold’s system by eliminating the system control
unit, attaching the processors directly to the memory bus,
adding a cache controller to each processor, and making the
cache controller snoop the bus and assume the locking function
formerly performed by Arnold’s centralized system control
unit. Appellants argue that Tipley’s distributed control
system suggests no such overhaul of Arnold’s centralized
control system. We agree with
appellants. Such a major change to Arnold can only be adopted
with impermissible use of hindsight. See Interconnect Planning
Corp. v. Feil, 774 F.2d 1132, 1143, 227 USPQ 543, 551 (Fed.
Cir. 1985). Therefore, we will not sustain the rejection.
Tetzlaff in view of Chan and Tipley
Tetzlaff has a centralized system for locking a portion
of main memory. Chan uses centralized system control units to
search for conflicts, specifically so that the distributed
processors are not burdened with performing cache coherency
resolution tasks. Column 6, lines 39-45. Tipley, as above
described, has no centralized system control units and
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