Apple A8

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.[11] Apple states that it has 25% more CPU performance and 50% more graphics performance while drawing only 50% of the power of its predecessor, the Apple A7.[12]

Apple A8
Apple A8 processor
General Info
LaunchedSeptember 9, 2014
DiscontinuedPresent
Designed byApple Inc.
Common manufacturer(s)
Product codeAPL1011[2]
Performance
Max. CPU clock rate1.1 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))[3] 
Cache
L1 cachePer core: 64 KB instruction + 64 KB data[4]
L2 cache1 MB shared[4]
L3 cache4 MB[4]
Architecture and classification
ApplicationMobile
Min. feature size20 nm[5]
MicroarchitectureTyphoon[6][7]
Instruction setARMv8-A: [4]A64, A32, T32
Physical specifications
Cores
GPU(s)Custom PowerVR Series 6XT (quad-core)[9][10]
Products, models, variants
Variant(s)Apple A8X
History
PredecessorApple A7
SuccessorApple A9

Design

The A8 is manufactured on a 20 nm process[5] by TSMC,[1] which replaced Samsung as the manufacturer of Apple's mobile device processors. It contains 2 billion transistors. Despite having twice the number of transistors of the A7, the A8's physical size has been reduced by 13% to 89 mm2 (0.138 in2).[8] The A8 uses LPDDR3-1333 RAM on a 64-bit memory interface; in the iPhone 6/6 Plus, sixth generation iPod touch, and HomePod, the A8 has 1 GB RAM included in the package.[2] Meanwhile, the A8 in the iPad Mini 4 and 4th generation Apple TV is packaged with 2 GB RAM.[13][14]

The A8 CPU has a per-core L1 cache of 64 KB for data and 64 KB for instructions, an L2 cache of 1 MB shared by both CPU cores, and a 4 MB L3 cache that services the entire SoC.[4] As its predecessor, it has a 6 decode, 6 issue, 9 wide, out-of-order design. The processor is dual core, and as used in the iPhone 6 has a frequency of 1.4 GHz, supporting Apple's claim of it being 25% faster than the A7.[15] It also supports the notion of this being a second generation[16] enhanced Cyclone core called Typhoon,[6][7] and not an entirely new architecture which would supposedly mean a more significant performance gain per Hz.[4]

The A8 also integrates a graphics processing unit (GPU) which is a 4-shader-cluster PowerVR Series 6XT.[17] However the GPU features custom shader cores designed by Apple.[10]

On October 16, 2014, Apple introduced a variant of the A8, the A8X, in the iPad Air 2. Compared with the A8, the A8X has an enhanced 8-shader-cluster GPU and improved CPU performance due to one extra core and higher frequency.

Patent litigation

The A8's branch predictor has been claimed to infringe on a 1998 patent.[18][19] 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 A7 and A8 processors.[19] The patent is owned by Wisconsin Alumni Research Foundation (WARF), a firm affiliated with the University of Wisconsin. On July 24, 2017, Apple was ordered to pay WARF $506 million for patent infringement. Apple filed an appellate brief on October 26, 2017, with the U.S. Court of Appeals for the Federal Circuit, that argued that Apple did not infringe on the patent owned by the Wisconsin Alumni Research Foundation.[20] On September 28, 2018, the ruling was overturned on appeal and the award thrown out by the U.S. Federal Circuit Court of Appeals.[21] The patent expired in December 2016.[22]

Products that include the Apple A8

See also

Notes
  1. Most analysts have reported that the Apple A8 is manufactured by TSMC, including Chipworks,[1] Techinsights,[23] and AnandTech.[24] An analyst at IHS reports that manufacturing is split, with TSMC manufacturing about 60 percent and Samsung manufacturing about 40 percent.[25]

References
  1. "Inside the iPhone 6 and iPhone 6 Plus". Chipworks. September 19, 2014. Archived from the original on 2014-09-24. Retrieved September 20, 2014.
  2. "iPhone 6 Plus Teardown". iFixit. September 18, 2014. Retrieved September 19, 2014.
  3. "iPad Mini 4 performance preview: A 1.5GHz Apple A8 with 2GB of RAM". Ars Technica. September 15, 2015. Retrieved September 16, 2015.
  4. "The iPhone 6 Review: A8's CPU: What Comes After Cyclone?". AnandTech. September 30, 2014. Retrieved September 30, 2014.
  5. Smith, Ryan (September 9, 2014). "Apple Announces A8 SoC". AnandTech. Retrieved September 9, 2014.
  6. The Samsung Exynos 7420 Deep Dive - Inside A Modern 14nm SoC
  7. Chester, Brandon (July 15, 2015). "Apple Refreshes The iPod Touch With A8 SoC And New Cameras". Retrieved September 11, 2015.
  8. Anthony, Sebastian. "Apple's A8 SoC analyzed: The iPhone 6 chip is a 2-billion-transistor 20nm monster". www.extremetech.com. ExtremeTech. Retrieved 10 September 2014.
  9. Smith, Ryan (September 23, 2014). "Chipworks Disassembles Apple's A8 SoC: GX6450, 4MB L3 Cache & More". AnandTech. Retrieved September 23, 2014.
  10. Kanter, David. "A Look Inside Apple's Custom GPU for the iPhone". Retrieved 2019-08-27.
  11. "Apple Announces iPhone 6 & iPhone 6 Plus—The Biggest Advancements in iPhone History" (Press release). Apple. September 9, 2014. Retrieved September 9, 2014.
  12. Savov, Vlad (September 9, 2014). "iPhone 6 and iPhone 6 Plus have a new faster A8 processor". The Verge. Vox Media. Retrieved September 9, 2014.
  13. Chester, Brandon (September 9, 2015). "Apple Announces the iPad Pro and iPad Mini 4". AnandTech. Retrieved September 9, 2015.
  14. "The New Apple TV". Apple Inc. September 9, 2015. Retrieved September 9, 2015.
  15. Alleged iPhone 6 Geekbench Results Reveal 1.4 GHz Dual-Core A8 Chip, 1 GB of RAM
  16. Apple - iPhone 6 - Technology
  17. "The iPhone 6 Review: A8's GPU: Imagination Technologies' PowerVR GX6450". AnandTech. September 30, 2014. Retrieved September 30, 2014.
  18. Chirgwin, Richard (February 4, 2014). "Cupertino copied processor pipelining claims Wisconsin U". www.theregister.co.uk. The Register. Retrieved February 3, 2014.
  19. Joe Mullin (October 14, 2015). "Apple faces $862M patent damage claim from University of Wisconsin". Ars Technica. Retrieved October 14, 2015.
  20. Wolfe, Jan (October 26, 2017). "Apple urges appeals court to toss $506 million patent loss to WARF". Reuters. Retrieved February 22, 2018.
  21. Stempel, Jonathan (September 28, 2018). "Apple wins reversal in University of Wisconsin patent lawsuit". Reuters. Retrieved November 17, 2018.
  22. Wolfe, Jan (July 25, 2017). "Apple ordered to pay $506 million to university in patent dispute". Reuters. Retrieved July 26, 2017.
  23. "Logic Detailed Structural Analysis of the 20 nm Node, TSMC Fabricated Apple A8 APL1011". Techinsights. August 28, 2015. Archived from the original on December 8, 2015. Retrieved December 3, 2015.
  24. Ho, Joshua (November 2, 2015). "The Apple iPhone 6s and iPhone 6s Plus Review: Analyzing Apple A9's SoC". AnandTech. Retrieved December 3, 2015.
  25. Hesseldahl, Arik (September 23, 2014). "Teardown Shows Apple's iPhone 6 Cost at Least $200 to Build". Re/code. Retrieved December 1, 2015.
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