Apple is rumored to release a 12.9-inch tablet in October 2014, targeting North America's educational market, according to sources from the upstream supply chain.

With Samsung Electronics also reportedly planning to release 12- to 13-inch tablets, the sources believe these large-size tablets will greatly impact ultrabook demand.

Apple's large-size tablet will be manufactured by Quanta Computer, and was originally expected to adopt either 12.9- or 13.3-inch panels, with recent rumors indicating that 12.9-inch has a better chance to be picked, the sources noted.

In addition to tablets, Apple is also rumored to be planning a larger size iPhone for May 2014, using a 20nm processor manufactured by Taiwan Semiconductor Manufacturing Company (TSMC), the sources noted.

As for whether the large-size tablet will also adopt the same processor, performance is expected to be a major factor as the tablet is being considered as a substitute of the 11-inch MacBook Air, the sources speculated.