When a PCI-bus controller receives a request from a PCI-bus master to transfer data with an address in secondary memory, the controller performs an initial inquire cycle and withholds TRDY# to the PCI-bus master until any write-back cycle completes. The controller then allows the burst access to take place between secondary memory and the PCI-bus master, and simultaneously and predictively, performs an inquire cycle of the L1 cache for the next cache line. In this manner, if the PCI burst continues past the cache line boundary, the new inquire cycle will already have taken place, or will already be in progress, thereby allowing the burst to proceed with, at most, a short delay. Predictive snoop cycles are not performed if the first transfer of a PCI-bus master access would be the last transfer before a cache line boundary is reached.
Alden Malley at AppleInsider wrote in a post OPTi wins $19 million from Apple in patent lawsuit:
Begun in January 2007, the lawsuit is a classic example of a firm suing based on very broadly worded patents designed to catch out and collect royalties from as many firms as possible, regardless of whether they were actually aware of the patent. OPTi had filed a similar suit against AMD despite its making processors Apple and other companies don't use; it also dropped all of its original manufacturing and sales businesses in 2003 to concentrate on its lawsuits as a primary source of income.
Apple for its part had tried to thwart the plaintiff by claiming that the patent was invalid both through prior art and through the obviousness of the techniques involved. Judge Charles Everingham of the Marshall court rejected both arguments in his verdict, letting the patent stand.
IPBiz note to Malley: They are called patents because they are publicly available. Because they are publicly available, "knowledge" or awareness is NOT required to find infringement. HOWEVER, Apple went down for willful infringement, meaning Apple was aware of the patent. Also, "obviousness" requires some prior art, even if one invokes common sense.