Apple’s A4 Chip Based on ARM Cortex-A8 and not Cortex-A9

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Submitted by lalit on March 1, 2010 - 10:02am.

Ars Technica speculates that Apple has kept mum about their A4 processor, as there isn’t anything to write home about. Jon Stokes of Ars Technica believes that the A4 processor is based on ARM Cortex-A8 design and not the latest ARM Cortex-A9. He wrote:

As I watched the videos and read the reports of the iPad in action at launch event, I was thoroughly convinced that the device was built on the out-of-order Cortex A9, possibly even a dual-core version. But it turns out that the A4 is a 1GHz custom SoC with a single Cortex A8 core and a PowerVR SGX GPU. The fact that A4 uses a single A8 core hasn’t been made public, but I’ve heard from multiple sources who are certain for different reasons that this is indeed the case. (I wish I could be more specific, but I can’t.)

He further adds A4 is almost like Cortex A8 SoC available on the market today, except A4 has even less hardware. A typical A8 SoC (image below) has infrared block, three UART blocks for serial communication, four USB blocks, keypad controller and other blocks. Whereas, iPad only requires blocks for 30-pin connector and multitouch input. Apple can just use UART and USB blocks removing other blocks from the chip design.

Jon also speculates that Apple probably ditched dedicated image processing blocks, as iPad comes without still or video camera. He says “with one 30-pin connector on the bottom and no integrated camera of any kind, the A4 needs a lot less in the way of I/O support than comparable chips”. The A4 chip is thus a combination of GPU, CPU, memory interface, security hardware, system hardware and few I/O controllers.

We agree with Jon that if Apple used Cortex-A8 design for A4 chip they would have decreased the number of I/O blocks to make the chip more efficient based on Apple’s needs for iPad. But we don’t believe that Apple ditched image processing blocks, because the camera is just one of the many functions image processing unit supports. Also if Apple is going to base their next generation iPhone on A4 like chip they can’t remove such an important part.

Many tech websites are also reporting that they have heard Apple is using A8 design for iPad, and most of our sources also agree. But one of our sources says that Apple might be using A9 core in the A4 chip, however he is not sure about the information.