The Apple "A" series is a family of "Systems on Chip" (SoC) used in the iPhone, iPad, iPod, and Apple TV. They integrate one or more ARM-based processing cores (CPU), a graphics processing unit (GPU), cache memory and other electronics necessary to provide integrated computing functions within a single physical package. They are specified by Apple, and manufactured by contract manufacturers such as Samsung. As technology improves with time the processing power available has been increased, while the die size and heat produced have been reduced. The A4 SoC in the first iPad uses a die manufactured on a 45 nm fabrication process with a single core CPU running at up to 1 GHz, whereas the latest A6X SoC used in the 4th generation iPad uses a 32 nm process with a dual-core CPU running at 1.4 GHz and quad-core GPU.

Apple A4[link]

The Apple A4 is a package on package (PoP) system on a chip (SoC) designed by Apple and manufactured by Samsung.^[1] It combines an ARM Cortex-A8 CPU with a PowerVR GPU, and emphasizes power efficiency.^[2] The chip commercially debuted with the release of Apple's iPad tablet;^[3] followed shortly by the iPhone 4 smartphone,^[4] the 4th generation iPod Touch and the 2nd generation Apple TV. It was superseded in the second-generation iPad, released the following year, by the Apple A5 processor.

Apple A4 is based on the ARM processor architecture.^[5] The first version released ran at 1 GHz for the iPad and contains an ARM Cortex-A8 CPU core paired with a PowerVR SGX 535 graphics processor (GPU)^[3][6][7][8] built on Samsung's 45-nanometer (nm) silicon chip fabrication process.^[9] The clock speed for the units used in the iPhone 4 and the iPod Touch (4th generation) is 800 MHz. The clock speed for the unit used in the Apple TV has not been revealed.

The Cortex-A8 core used in the A4 is thought to use performance enhancements developed by chip designer Intrinsity (which was subsequently acquired by Apple)^[10] in collaboration with Samsung.^[11] The resulting core, dubbed "Hummingbird", is able to run at far higher clock rates than other implementations while remaining fully compatible with the Cortex-A8 design provided by ARM.^[12] Other performance improvements include additional L2 cache. The same Cortex-A8 CPU core used in the A4 is also used in Samsung's S5PC110A01 SoC.^[13][14] The SGX535 in the A4 could push 35 million polygons/second and 500 million pixels/second, although in real world tests it struggled to pull off even 7 million flat shaded polygons.^[15]

The A4 processor package does not contain RAM, but supports PoP installation. The top package of the A4 used in the iPad, in the iPod Touch^[16] 4th gen and in the Apple TV^[17] 2nd gen contains two low-power 128 MB DDR SDRAM chips for a total of 256MB RAM. For the iPhone 4 there are two chips of 256 MB for a total of 512 MB.^[18][19][20] RAM is connected to the processor using ARM's 64-bit-wide AMBA 3 AXI bus. This is twice the width of the RAM data bus used in previous ARM 11 and ARM 9 based Apple devices, to support the greater need for graphics bandwidth in the iPad.^[21]

Apple A5[link]

The Apple A5 is a package on package (PoP) system on a chip (SoC) designed by Apple and manufactured by Samsung^[22] that replaced the A4. The chip commercially debuted with the release of Apple's iPad 2 tablet in March 2011,^[23] followed by its release in the iPhone 4S smartphone later that year. (This is consistent with how Apple debuted the A4 chip: first in the original iPad, then in the iPhone 4, and finally in the 4th generation iPod touch.^[24])

The A5 contains a dual-core ARM Cortex-A9 CPU^[25] with ARM's advanced SIMD extension, marketed as NEON, and a dual core PowerVR SGX543MP2 GPU. This GPU can push between 70 and 80 million polygons/second and has a pixel fill rate of 2 billion pixels/second. Apple lists the A5 to be clocked at 1 GHz on the iPad 2's technical specifications page,^[26] though it can dynamically adjust its frequency to save battery life.^[25][27] The clock speed of the unit used in the iPhone 4S is 800 MHz.

Apple states that the CPU is "twice as powerful" and the GPU up to "nine times as powerful" as its predecessor, the Apple A4. The A5 package contains 512 MB of low-power DDR2 RAM.^[28] The A5 is estimated to cost 75% more than its predecessor; the price difference is supposed to diminish as production increases.^[29]

The third generation Apple TV, the iPad Mini, and the new version of iPad 2 (version iPad2,4) contain a 32 nm version of the A5 processor. The chip in the Apple TV has one core disabled.^[30][31] The markings of the square package indicates that it's named APL2498, and in software, the chip is called S5L8942. The 32 nm variant of the A5 provides around 15% better battery life during web browsing, 30% better when playing 3D games and approximately 20% better battery life during video playback.^[32]

Apple A5X[link]

Apple A5X was announced on March 7, 2012 at the launch of the iPad (3rd generation). This SoC has a quad-core graphics unit (PowerVR SGX543MP4) instead of the previous dual-core as well as a quad-channel memory controller that provides a memory bandwidth of 12.8 GB/sec, roughly three times more than in the A5. The added graphics cores and extra memory channels add up to a very large die size of 163 mm², for example twice the size of Nvidia Tegra 3.^[33] This is mainly due to the large PowerVR SGX543MP4 GPU. The clock frequency of the dual ARM Cortex-A9 cores have been shown to operate at the same 1 GHz frequency as in A5.^[34] The RAM in A5X is separate from the main CPU package.^[35]

Apple A6[link]

The Apple A6 was announced on September 12, 2012 at the launch of the iPhone 5. It is 22% smaller, twice as fast, has twice the graphics performance, and draws less power than the 45 nm A5.^[36] The CPU uses a modified ARM instruction set called ARMv7s^[37] which means that the CPU is not a strict ARM licensed CPU but instead a custom built ARM Cortex like CPU, similar to how Qualcomm makes CPUs. The support for VFPv4 extensions suggests that it is a Cortex-A15 class CPU. The GPU is a triple core PowerVR SGX543MP3 running at 266 MHz.

Apple A6X[link]

The Apple A6X was introduced with the fourth generation iPad in October 2012. It has dual Swift cores, just as the A6, but has a new quad core GPU, quad channel memory and higher clock speed.

According to Anandtech and ChipWorks, maximum clock speed is 1.4 GHz, and GPU is PowerVR SGX554MP4.^[38][39]

List of Apple SoCs[link]

Name	Model no.	Image	Semiconductor technology	Die size	CPU ISA	CPU	CPU cache	GPU	Memory technology	Introduced	Utilizing devices
	APL0098		90 nm		ARMv6	412 MHz single-core ARM11	L1: 16 kB Instruction + 16 kB Data	PowerVR MBX Lite @ 103 MHz	32-bit Single-channel 103 MHz LPDDR	June 2007	iPhone iPod Touch (1st gen) iPhone 3G
	APL0278		65 nm		ARMv6	412–533 MHz single-core ARM11	L1: 16 kB Instruction + 16 kB Data	PowerVR MBX Lite @ 103–133 MHz	32-bit Single-channel 133 MHz LPDDR	September 2008	iPod Touch (2nd gen.) iPod Nano (4th gen.) iPod Touch (3rd gen.; only 8GB)
	APL0298		65 nm	71.8 mm2	ARMv7	600 MHz single-core Cortex-A8	L1: 32 kB Instruction + 32 kB Data, L2: 256 kB	PowerVR SGX535 @ 150 MHz (1.2 GFLOPS)	32-bit Single-channel 200 MHz LPDDR (1.6 GB/sec)	June 2009	iPhone 3GS
	APL2298		45 nm		ARMv7	600–800 MHz single-core Cortex-A8	L1: 32 kB Instruction + 32 kB Data, L2: 256 kB	PowerVR SGX535 @ 150–200 MHz (1.2–1.6 GFLOPS)	32-bit Single-channel 200 MHz LPDDR (1.6 GB/sec)	September 2009	iPod Touch (3rd gen.; except 8GB)
A4	APL0398		45 nm	53.29 mm2	ARMv7	0.8–1.0 GHz single-core Cortex-A8	L1: 32 kB Instruction + 32 kB Data, L2: 512 kB	PowerVR SGX535 @ 200–250 MHz (1.6–2 GFLOPS)[40]	32-bit Dual-channel 200 MHz LPDDR (3.2 GB/sec)	March 2010	iPad iPhone 4 iPod Touch (4th gen.) Apple TV (2nd gen.)
A5	APL0498		45 nm	122.6 mm2	ARMv7	0.8–1.0 GHz dual-core Cortex-A9	L1: 32 kB instruction + 32 kB data, L2: 1 MB	PowerVR SGX543MP2 (dual-core) @ 200–250 MHz (12.8–16 GFLOPS)[40]	32-bit Dual-channel 400 MHz LPDDR2-800 (6.4 GB/sec)	March 2011	iPad 2 iPhone 4S
	APL2498		32 nm HKMG	71.1 mm2	ARMv7	0.8–1.0 GHz dual-core Cortex-A9 (one core disabled in Apple TV)	L1: 32 kB instruction + 32 kB data, L2: 1 MB	PowerVR SGX543MP2 (dual-core) @ 200–250 MHz (12.8–16 GFLOPS)[40]	32-bit Dual-channel 400 MHz LPDDR2-800 (6.4 GB/sec)	March 2012	Apple TV (3rd gen.) iPad 2 (iPad2,4) iPod Touch (5th gen.) iPad Mini
A5X	APL5498		45 nm	162.94 mm2[33]	ARMv7	1.0 GHz dual-core Cortex-A9	L1: 32 kB instruction + 32 kB data, L2: 1 MB	PowerVR SGX543MP4 (quad-core) @ 250 MHz (32 GFLOPS)[40]	32-bit Quad-channel 400 MHz LPDDR2-800[41] (12.8 GB/sec)	March 2012	iPad (3rd gen.)
A6	APL0598		32 nm HKMG[42]	96.71 mm2[42]	ARMv7s	1.3 GHz[43] dual-core Swift[37]	L1: 32 kB instruction + 32 kB data, L2: 1 MB[44]	PowerVR SGX543MP3 (tri-core) @ 266 MHz (25.5 GFLOPS)[45]	32-bit Dual-channel 533 MHz LPDDR2-1066[46] (8.528 GB/sec)	September 2012	iPhone 5
A6X	APL5598		32 nm HKMG[39]	123 mm2[39]	ARMv7s	1.4 GHz dual-core Swift[38]	L1: 32 kB instruction + 32 kB data, L2: 1 MB	PowerVR SGX554MP4 (quad-core) @ 280 MHz (71.6 GFLOPS)[38][47]	32-bit Quad-channel 533 MHz LPDDR2-1066 (17 GB/sec)[48]	October 2012	iPad (4th gen)

See also[link]

• List of Samsung System on a Chip
• Allwinner
• ARM Cortex-A9 MPCore
• PowerVR SGX GPUs were also used in the iPhone 3GS and the third-generation iPod Touch
• PWRficient, a processor designed by P.A. Semi, a company Apple acquired to form an in-house custom chip design department
• Rockchip

Similar platforms[link]

• Exynos by Samsung
• Snapdragon by Qualcomm
• Atom by Intel
• NovaThor by ST-Ericsson
• OMAP by Texas Instruments
• Tegra by Nvidia

References[link]

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