Apple A8

Apple A8 SoC

The Apple A8 is one of the US company Apple developed and the Taiwanese company TSMC manufactured system on a chip (SoC). It combines a 64-bit - ARM - CPU with a graphics processor and main memory and also takes over the functions of a conventional PC chipset . It works around 25% faster and uses around 50% less energy than its predecessor, the Apple A7 . Its successor is the Apple A9 .

history

The A8 is the first SoC from Apple that is no longer produced by Samsung, but by TSMC. The collaboration between Apple and Samsung ended after a good seven years in SoC production. The A8 was presented on September 9, 2014 as part of the iPhone 6 and 6 Plus and is supported in these devices by the Apple M8 sensor coprocessor . Apple's A8 chip has also been used in the sixth generation of the iPod Touch since July 15, 2015, in the fourth generation of Apple TV since October 30, 2015, and in the Apple HomePod since February 9, 2018 .

The A8's processor was said to contain technology protected by a patent owned by the University of Wisconsin . As a result, the company was set to pay $ 506 million in damages for patent infringement. The judgment was put down in an appeal in 2017.

technology

The A8 SoC with the name APL1011 used in the iPhone 6 and 6 Plus each have two RISC processor cores clocked at 1.4  GHz ; the core clock in the iPod touch is reduced to 1.1 GHz. In the iPad mini 4 introduced in 2015, the CPU clocked at 1.5 GHz. The A8 supports the 64-bit ARMv8 instruction set and is backward compatible with the 32-bit ARMv7 and ARMv6 instruction set. The micro- architecture called Typhoon is an in-house development by Apple. Compared to the first Cyclone generation, it achieves 16 percent higher processing power (IPC, instructions per clock cycle), as the clock frequency only increased by 8 percent compared to the Apple A7 .

The A8 addresses 1 GB LPDDR3-SDRAM memory in the iPhone and iPod touch via a 64-bit wide address bus, and 2 GB in the iPad mini 4 and in the Apple TV 4, which is clocked at 1333 MHz. The A8 is manufactured using the 20 nm process. Due to the changed manufacturing process, two billion transistors fit on the chip. A PowerVR GX6450 is used as the GPU, not only can you find information about this in Apple's developer documentation, a die photo also shows that the GX6450 is a 4-cluster configuration.

In addition to the CPU and GPU, there is also a 4 MB SRAM L3 cache on the die as a significant block, which is shared between the CPU and GPU. The die of the Apple A8 is 88.9 mm² (8.47 mm × 10.5 mm), of which 12.2 mm² is used by the CPU block with L1 and L2 caches and 19.1 mm² by the GPU Logic occupied.

Microarchitecture

Block diagram of Apple's second generation 64-bit Cyclone CPU.

The processor cores of the Apple A8 were not licensed by Apple directly from ARM , but by means of a so-called ARM architecture license, which u. a. and the chip maker Qualcomm for its Snapdragon - SoCs uses, as a successor to the Cyclone CPU from the Apple A7 developed. Since Apple hardly publishes any technical information about Cyclone itself, there is only limited reliable information about the microarchitecture.

Electronics editor Frank Riemenschneider tried to draw conclusions about the micro-architecture of Cyclone using information published by Apple, an iPhone 6 and apps he developed himself . The presented block diagram of the second generation of Cyclone is the only one of its kind published to date.

Individual evidence

1. ↑ Inside the iPhone 6 and iPhone 6 Plus. In: Chipworks Blog. September 19, 2014, accessed February 2, 2015 . 
2. ↑ ^{a b c d} Frank Riemenschneider on Elektroniknet: New engine for iPhone 6: The photo proves Apple A8 with GPU PowerVR GX6450 , September 10, 2014, accessed on September 23, 2014
3. ↑ Sebastian Anthony: Apple's A8 SoC analyzed: The iPhone 6 chip is a 2-billion-transistor 20nm monster , published on September 10, 2014, accessed on February 24, 2015
4. ↑ Benjamin Mayo on 9to5mac: Samsung's SoC profits down as Apple chooses TSMC for A8, although rumor says it will produce processors for iPhone 7 , August 5, 2014, accessed on September 10, 2014
5. ↑ Peter K. on Phonearena: Technology explained: here's how the A8 chip makes the Apple iPhone 6 click and tick , September 12, 2014, accessed on September 13, 2014
6. ↑ Patent dispute: Apple sentenced to US university to pay damages. $ 234 million for stolen patents: Apple has to pay fine to the University of Wisconsin. The affected technology can also be found in various iPhone versions. In: ZEIT ONLINE. ZEIT ONLINE GmbH, October 18, 2015, accessed on October 18, 2015 . 
7. ↑ Apple is supposed to pay half a billion dollars in patent litigation , APA report on derstandard.at of July 26, 2017, accessed on July 31, 2017.
8. ↑ Macerkopf: iPod touch 6G is here: A8 and M8 chips, 8MP camera, Bluetooth 4.1, 128GB option and more , July 15, 2015
9. ↑ ^{a b} Cunningham, Andrew in Ars Technica : iPad Mini 4 performance preview: A 1.5GHz Apple A8 with 2GB of RAM . Released September 15, 2015, accessed September 24, 2015
10. ↑ Benjamin Mayo in 9to5mac: Supposed iPhone 6 ran through Geekbench, once again suggests 1 GB RAM, dual-core A8 , September 9, 2014, accessed on September 10, 2014
11. ↑ Sebastian Anthony on Extreme Tech : Apple's A8 SoC analyzed: The iPhone 6 chip is a 2-billion-transistor 20nm monster , published on September 10, 2014, accessed on September 17, 2014 (English)
12. ↑ Frank Riemenschneider : Second Cyclone generation is the most powerful ARM CPU of all time. Report to Elektroniknet.de from September 30, 2014.

Web links

• The iPhone 6 Review - A8: Apple's First 20nm SoC , Review by AnandTech