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* Other companies have introduced chips with confusingly similar designations. The Apple A7/A8/A9/A10/... chips are not ARM designs and have nothing to do with the similarly-named Cortex-A7/-A9/... (or any other Cortex cores); the Apple A7, for example, is roughly in the same performance category as a dual-core Cortex-A53. Allwinner and AMD have also used chip designations starting with A (Allwinner A10, A20, and A80, and AMD Opteron A1100, for example); these are unrelated to the Apple A-series chips and to the Cortex A designations. Likewise, the Nvidia K1 is unrelated to the AMD K12.
== big.LITTLE and DynamIQ==
ARM cores may be combined in compatible groups of higher-performance/high-consumption and lower-performance/lower-consumption devices. These configurations are were enabled by a technology which Arm called big.LITTLE, and a related but newer cluster technology which Arm calls DynamIQ.
Balancing power vs. performance can be very difficult - for example, will it require less energy to keep a little core on constantly to perform a background task, or run a big core for a fraction of a second every few seconds and sleep all of the cores the rest of the time? Issues such as core affinity and cache coherency also play into balancing decisions.
Wikipedia has a [http://en.wikipedia.org/wiki/ARM_big.LITTLE page on big.LITTLE] that includes a list of known implementations.