Apple may face $900m bill after A7 CPU in iPhones, iPads ripped off university's patent

Apple's A7 processors in iPhones and iPads infringe a patent held by the University of Wisconsin, a court has ruled.

A jury, sitting in a US district court in Madison, Wisconsin, found Apple guilty of patent infringement late yesterday afternoon. While the damages in the case have yet to be determined, Judge William Conley previously set the possible payout to the college as high as $862m. Apple declined to comment on the case.

The US patent in question – 5,781,752 – describes a way for processors to order the execution of instructions. Modern CPUs can execute the instructions in software programs out of order [PDF] to optimize performance – some instructions can run ahead of schedule if a previous instruction is taking a long time, thus maximizing the processor's throughput.

The problem here is making sure instructions running out of order don't change memory and register values in a way that will break the running program. The uni's boffins invented a table-like structure for the processor to keep track of data dependencies – a technique also used by the A7 chips without the uni's permission.

The college's complaint [PDF] accused Apple of refusing to engage in any licensing talks with the university.

"The inventors are leading researchers in the field of computer microprocessor architecture," the uni alleged.

"Their work at the University of Wisconsin–Madison, particularly the work for which they were awarded the patent-in-suit, significantly improved the efficiency and performance of contemporary computer processors."

The same patent, granted in 1998, had been cited in a 2008 infringement case with Intel that was settled out of court.

Apple used the ARM-compatible A7 processor to power its iPhone 5S smartphone and the iPad Air, iPad Mini 2, and iPad Mini 3 tablets. The university filed suit last year on behalf of its Wisconsin Alumni Research Foundation (WARF).

Apple had countered that the patent was invalid and had suggested WARF was a patent troll. The jury rejected Apple's counterclaim while at the same time finding Apple trampled over the '752 patent.

While the A7 is compatible with the ARMv8 architecture, the system-on-chip was designed by Apple from scratch, and the processor's 64-bit instruction set was licensed from ARM. It was this custom design – this particular implementation of ARMv8 – by Apple that stepped on the university's toes. In other words, this ain't ARM's problem. ®