TechPulse 360

The A4 is Apple's custom chip powering the iPad tablet

[Update] Analyst Jon Peddie just blogged more details about iPad’s internals.

Inside Apple’s upcoming iPad tablet lies a mysterious chip: the A4, with the “A” presumably referring to Apple and the number “4″ perhaps to 4-cores!

First, here’s what we know for sure about the A4, either from common sense and public comments by Apple:

1. It’s a system-on-a-chip (SoC) which combines a low-power ARM-based CPU (supposedly the latest Cortex A9), a graphics processor (or GPU), and other circuitries like audio and video codecs.
2. Runs at 1GHz;
3. Fabricated by Samsung.

In many aspects, Apple’s custom silicon is comparable to next-generation ARM-based SoC mobile processors from Freescale (i.MX series), Marvell (Armada), Qualcomm (SnapDragon) and Nvidia (Tegra); all showed at CES a number of tablets and netbooks prototypes using their respective chips.

Intel has also entered the SoC market with its Moorestown chip, a shrink of the current Atom processor used in netbooks, which now integrates a CPU and GPU on the same die.

If there’s not much mystery left on the origin of the A4 CPU – aside from the number of cores – little is still known however of the internal design of the chip and its graphics capabilities.

In a blog post that was widely reprinted all over the Net, Brightside suggested that Apple used ARM’s Mali 50 design for its core GPU. However, graphics expert Jon Peddie, of Jon Peddie Research, disagrees.

“The Ipad is not using Mali,” told Peddie to TechPulse 360. “The graphics engine in iPad certainly do, spec-wise, rival Tegra, Snapdragon, or Armada. On a polygons/second, or a pixel fill-rate basis it is as good as any out there, maybe better. And if game play is the criteria, then the graphics engine has all the power needed to deliver a very satisfying, if not impressive experience.”

But for Peddie, the real question should be: how does the A4 chip compares on a polygons/second/watt basis?

“And here is where you (and competitors) will be surprised – it will be top of the class. We won’t have measured data probably until late summer when all the tablets, including HP’s Slate and MSI’s Tegra-based unit are out and available for testing. But based on what we know about the engines involved, the A4 should be the best of breed,” added Peddie who is coming out next week with a full report on the A4 chip.

Peddie just blogged more details on the A4′s graphics engine: it’s an Imagination Technologies [PowerVR] SGX 535 core that is already used in iPhones and iPod touches.

Earlier this month at CES, Imagination unveiled a successor to the 535 core – the 545 – with even more impressive graphics capabilities. No doubt that it will find its way in next-generation iPhones, iPods and iPads.

Apple and Intel are key stockholders in Imagination Technologies. According to the UK publicly-listed company, they respectively own 9.5% and 16% (according to the Guardian) of its shares.