Designed by Apple Inc. Min. feature size 20 nm | Common manufacturer(s) TSMC Instruction set A64, A32, T32 | |
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Produced From September 9, 2014 to Present Max. CPU clock rate 1.1 GHz (iPod Touch 6th generation) to 1.4 GHz (iPhone 6, iPhone 6 Plus) and 1.5 GHz (iPad mini 4 & Apple TV (4th Gen)) | ||
The Apple A8 is a 64-bit ARM based system on a chip (SoC) designed by Apple Inc. It first appeared in the iPhone 6 and iPhone 6 Plus, which were introduced on September 9, 2014. Apple states that it has 25% more CPU performance and 50% more graphics performance while drawing only 50% of the power compared to its predecessor, the Apple A7.
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Design
The A8 is manufactured on a 20 nm process by TSMC, which replaced Samsung as the manufacturer of Apple's mobile device processors. It contains 2 billion transistors. Despite having twice the number of transistors compared to the A7, the A8's physical size has been reduced by 13% to 89 mm2. The A8 in the iPhone 6 and 6 Plus has 1 GB of LPDDR3 RAM included in the package, while the A8 in the iPad Mini 4 and 4th generation Apple TV is packaged with 2 GB of LPDDR3 RAM.
The A8 has a per-core L1 cache of 64 KB for data and 64 KB for instructions, a L2 cache of 1 MB shared by both CPU cores, and a 4 MB L3 cache that services the entire SoC.
Benchmarks suggest that the processor is dual core, and as used in the iPhone 6 has a frequency of 1.38 GHz, supporting Apple's claim of it being 25% faster than the A7. It also supports the notion of this being a second generation enhanced Cyclone core called Typhoon, and not an entirely new architecture which would supposedly mean a more significant performance gain per Hz.
The A8 also integrates a graphics processing unit (GPU) which AnandTech believes to be a 4-cluster PowerVR GX6450.
On October 16, 2014, Apple introduced a variant of the A8, the A8X, in the iPad Air 2. Compared to the A8, the A8X has improved graphics and CPU performance due to one extra core and higher frequency.
Patent litigation
On October 14, 2015, a district judge found Apple guilty of infringing U.S. patent US 5781752 , "Table based data speculation circuit for parallel processing computer", on the Apple A8 and A7 processors. The patent is owned by Wisconsin Alumni Research Foundation, a firm affiliated with the University of Wisconsin. The company could be liable for up to US$862.4 million in damages.