Apple A4

iPhone 4 logic board with the EMI shield removed

The Apple A4 is one of Apple developed and Samsung manufactured system on a chip (SoC). The A4 was developed from 2008 by Apple's internal chip design department under the direction of Johny Sroujis , which emerged from the acquired company PA Semi . It combines an ARM - CPU with a PowerVR - GPU and also performs the functions of a conventional PC chipset . The A4 is the same as its predecessor, with the exception of minimal changes in the details of cache size and multiplier . Often the name Apple A4 is used alone for the ARM processor, but this is not strictly correct. The internal name Samsung S5L89xx of the predecessor SoCs was retained in the A4, the name Apple A4 is used for marketing. The actual designation of the A4 is S5L8930 , so the A4 still belongs to the S5L SoCs .

The predecessor of the A4 was the S5L8922 , the successor to the Apple A5 .

The A4 was with the iPad the first generation introduced on January 27 of 2010. It was also used in the iPhone 4 , the 4th generation iPod touch and the 2nd generation Apple TV .

description

Apple A4 chip

The System-on-a-Chip connects the CPU, integrated GPU and other parts. There is little information about the components used. An ARM Cortex A8 core with a maximum clock frequency of 1  GHz (in the iPad) is used as the main processor . The standard clock frequency in the iPhone 4 is 800 MHz, in the iPod touch 4G 776 MHz. The graphics processor is a PowerVR SGX 535 supported by a PowerVR VXD for audio and video playback. The latter was licensed from Imagination Technologies , as can be read in their annual report dated December 18, 2009. The A4 supports OpenGL ES 2.0, OpenGL 2.0 as well as OpenVG 1.0.1 and 1.1.

Competing architectures of similar products are Qualcomm's Snapdragon , Texas Instruments ' OMAP 4 , Nvidia's Tegra 2, and Samsung Exynos .

At the beginning of April 2010, the website iFixit had the Apple A4 installed in the iPad examined by the Canadian company Chipworks. For this purpose, the chip was ground layer by layer, treated with acid and examined under an electron microscope. The investigation produced the following results:

• The chip consists of several layers arranged one above the other with three dies in a multi-chip module design.
• Two layers are each a DDR-SDRAM from Samsung with 1 GBit (128 megabytes) storage capacity each (a total of 256 megabytes); the storage capacity of the iPhone 4 has been doubled to 512 MB.
• The third layer is the actual ARM Cortex A8 processor core.

Design flaw

A design flaw in the older S5L89xx iPhone main processors was adopted in the A4 chip: Any code can be executed using the so-called limera1n exploit, which was mainly used by jailbreaks . This bug, which cannot be patched by software updates, also allows the iPhone's code lock to be read out within a few minutes without great effort by executing a brute force program. This error has been fixed with the successor, the Apple A5.

Trivia

Apple A4 chip with the typical lettering of the S5L SoCs designed by PA Semi . S5L8930 is printed mirror-inverted here as APL0398 .

The look of the A4 chip propagated by Apple was only introduced with the finished iPads, while the A4 SoCs in the prototypes of the iPad were similar in their lettering to the previous S5L SoCs designed by PA Semi .

Web links

• cnet news

Individual evidence

1. ↑ iPhone 4 and Samsung Wave supposedly use the same processor , ZDNet.de, June 10, 2010
2. ↑ Imagination Technologies Group plc Annual Report 2009 . P. 14.
3. ↑ Apple A4 teardown
4. ↑ Hack2Learn - Apple has probably patched the Limera1n eploit ( memento of the original from December 30, 2013 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , accessed December 29, 2013, 11:20 am  
5. ↑ iPad Prototype Logicboard , accessed January 15, 2014, 2:35 pm