Apple A9

Apple A9

Apple A9 processor
Produced From September 9, 2015 to Present
Designed by Apple Inc.
Common manufacturer(s)
Max. CPU clock rate 1.85 GHz (iPhone 6s, iPhone 6s Plus, iPhone SE)[1][2] 
Min. feature size 16 nm (TSMC) to 14 nm (Samsung)
Instruction set A64, A32, T32
Microarchitecture Twister[3][4] ARMv8-A-compatible
Product code APL0898,[5] APL1022[6]
Cores 2[7]
L1 cache Per core: 64 KB instruction + 64 KB data
L2 cache 3 MB shared[7]
L3 cache 4 MB shared[8]
Predecessor Apple A8
GPU PowerVR Series 7XT GT7600 (six-core) [9][10]
Application Mobile
Variant Apple A9X

The Apple A9 is a 64-bit system-on-chip (SoC), designed by Apple Inc. Manufactured for Apple by both Samsung and TSMC, it first appeared in the iPhone 6S and 6S Plus which were introduced on September 9, 2015.[11] Apple states that it has 70% more CPU performance and 90% more graphics performance compared to its predecessor, the Apple A8,[11] and is currently one of the most powerful and energy-efficient mobile chips on the market today along with the Samsung Exynos 8890 and Qualcomm Snapdragon 820.

Design

The A9 features an Apple-designed 64-bit 1.85 GHz[1] ARMv8-A dual-core[7] CPU called Twister.[4] The A9 in the iPhone 6S has 2 GB of LPDDR4 RAM included in the package.[5][7] The A9 has a per-core L1 cache of 64 KB for data and 64 KB for instructions, an L2 cache of 3 MB shared by both CPU cores, and a 4 MB L3 cache that services the entire SoC and acts as a victim cache.[8]

The A9 includes a new image processor, a feature originally introduced in the A5 and last updated in the A7, with better temporal and spatial noise reduction as well as improved local tone mapping.[12] The A9 directly integrates an embedded M9 motion coprocessor, a feature originally introduced with the A7 as a separate chip. In addition to servicing the accelerometer, gyroscope, compass, and barometer, the M9 coprocessor can recognize Siri voice commands.[12]

The A9 features a custom storage solution, which uses an Apple-designed NVMe-based controller that communicates over a PCIe connection.[13] The iPhone 6s' NAND design is more akin to a PC-class SSD than embedded flash memory common on mobile devices. This gives the phone a significant storage performance advantage over competitors which often use eMMC or UFS to connect to their flash memory.

Microarchitecture

A9 microarchitecture is similar to second generation Cyclone (used in A8 chip) microarchitecture. Some of the microarchitectural features are as following: Pipeline depth (stages) 16, Issuewidth 6, ROB 192, Load latency (cy) 4, Mispredict penalty (cy) 9, Num of int pipes 4, Num of shifter ALUs 4, Load/Store Units 2, Int pipe buffer size 48, Num of branch units 2, Indirect branch units 1, Branch pipe buffer size 24, FP ALUs 3,

About half of the performance boost over A8 comes from the 1.85 GHz freq. About a quarter comes from the better memory subsystem (3x bigger caches). The remaining quarter comes from the microarchitectural tuning and smaller technology node.

Dual sourcing

Apple A9 chips are fabricated by two companies: Samsung and TSMC. The Samsung version is called APL0898, which is manufactured on a 14 nm FinFET process and is 96 mm2 large, while the TSMC version is called APL1022, which is manufactured on a 16 nm FinFET process and is 104.5 mm2 large. Despite these differences, difference in performance is not expected.[14]

In October 2015, a controversy emerged after it was alleged that iPhone 6S models with Samsung-fabricated A9 chips had slightly lower battery life than those with TSMC-fabricated versions, as determined by a benchmarking test.[15] Apple argued that "certain manufactured lab tests which run the processors with a continuous heavy workload until the battery depletes are not representative of real-world usage, since they spend an unrealistic amount of time at the highest CPU performance state", and that internal testing combined with customer data only demonstrated a variance of 2-3%.[16][17]

Naming

While the Twister CPU core implements the ARMv8-A architecture licensed from ARM Holdings, it is an independent CPU design and is unrelated to the much older but similarly named Cortex-A9 and ARM9 CPU that are designed by ARM themselves and implement the 32-bit ARMv7-A and ARMv5E versions of the architecture.

Gallery

The processors are nearly identical visually. The packaging have the same dimensions (approx 15.0×14.5 mm) and only superficial differences, like the designation text. Inside the packaging the silicon die differs in size.

Products that include the Apple A9

See also

References

  1. 1 2 "iPhone 6s customer receives her device early, benchmarks show a marked increase in power". iDownloadBlog. September 21, 2015. Retrieved September 25, 2015.
  2. ↑ "Revealed: iPhone 6S uses 1.85GHz dual-core A9 chip". Trusted Reviews. September 18, 2015. Retrieved September 25, 2015.
  3. ↑ Joshua Ho. "iPhone 6s and iPhone 6s Plus Preliminary Results".
  4. 1 2 Joshua Ho, Ryan Smith. "A9’s CPU: Twister - The Apple iPhone 6s and iPhone 6s Plus Review".
  5. 1 2 "iPhone 6s Teardown". iFixit. September 25, 2015. Retrieved September 26, 2015.
  6. ↑ "A9 is TSMC 16nm FinFET and Samsung Fabbed".
  7. 1 2 3 4 "Inside the iPhone 6s". Chipworks. September 25, 2015. Retrieved September 26, 2015.
  8. 1 2 Smith, Ryan (November 30, 2015). "Correcting Apple's A9 SoC L3 Cache Size: A 4MB Victim Cache". AnandTech. Retrieved 1 December 2015.
  9. ↑ "iPhone 6S Review". GSM Arena. October 2015.
  10. ↑ "Apple A9 / PowerVR GT7600". NotebookCheck. September 2015.
  11. 1 2 "Apple Introduces iPhone 6s & iPhone 6s Plus" (Press release). Apple. September 9, 2015. Retrieved September 9, 2015.
  12. 1 2 "iPhone 6s - Technology". Apple. September 8, 2015. Retrieved September 10, 2015.
  13. ↑ "The Apple iPhone 6s and iPhone 6s Plus Review". Anandtech. November 2, 2015. Retrieved April 4, 2016.
  14. ↑ Smith, Ryan (September 28, 2015). "Apple’s A9 SoC Is Dual Sourced From Samsung & TSMC". AnandTech. Retrieved 30 September 2015.
  15. ↑ Cunningham, Andrew (12 October 2015). "Samsung vs. TSMC: Comparing the battery life of two Apple A9s". Ars Technica (Condé Nast). Retrieved 13 October 2015.
  16. ↑ "Analyzing Apple's Statement on TSMC and Samsung A9 SoCs". Anandtech. Retrieved 11 October 2015.
  17. ↑ Barrett, Brian. "It Doesn't Matter Which A9 Chip Your iPhone Has. Get Over It.". Wired. Retrieved 11 October 2015.
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