Tech Analysis: Apple iPad

Digital Foundry explores a new front in the handheld gaming war.

The cat's out of the bag. Apple's much-vaunted tablet isn't the premium-priced touchscreen MacBook that many thought it would be, it's a completely re-engineered bigger brother to the iPod Touch, running an enhanced iPhone OS and featuring brand new applications with a typically stunning user interface.

"Our most advanced technology in a magical and revolutionary device at an unbelievable price," says Apple. But beneath the glass and aluminium shell, what powers the iPad, what are the implications for gaming, and what options are there for Sony and Nintendo to respond against this innovative new competitor in the handheld market?

The complete technical make-up of the new tablet is something that is not going to be 100 per cent confirmed until the likes of iFixit have done their customary teardown, but basic functionality is very similar indeed to the iPhone 3GS in terms of the accelerometer, ambient light detector, Bluetooth and even the compass. It's got Wi-Fi too, supporting the new 802.11n standard - a useful boost over the 3GS. The iPad's cellular 3G support is optional, and with that comes GPS functionality too. There's the expected full capacitive touch-screen, covering a top-tier IPS screen with LED backlighting. So far, so good.

More curious is the technical configuration of the main CPU and 3D accelerator. Apple has never been particularly forthcoming about these elements in the iPhone and iPod Touch, and this crucial aspect of the hardware was brushed over in seconds during Steve Jobs' presentation: it's called the A4, it's proprietary, and it runs at 1GHz. It's also more than just a CPU. It's a SOC, or "system on chip", combining all major processing elements into one piece of silicon. This keeps costs down and also reduces the power draw of the system: iPad ships with a 10-watt USB power supply.

Virtually nothing is known for sure about the make-up of the A4 chip, but there are some fundamental assumptions you can make, simply by virtue of the fact that iPad is compatible with the vast majority of iPhone applications and runs the same OS. It's massively unlikely that Apple would emulate the ARM chips found inside its other devices - it's hugely inefficient to do so - and it stands to reason that there's a hefty chunk of ARM IP in the new A4; it's been speculated that the ARM Cortex A8 or even the more powerful A9 may be a core element of Apple's own chip.

There's been a fair amount of speculation that the A4 chip also includes graphics acceleration technology licensed from ARM too (specifically the Mali200 or better), but it seems odd that Apple - which has a very successful, multi-year deal with PowerVR creator IMG - would not use the same tech in iPad, if only to ensure the best level of compatibility between all its mobile devices. IMG's range of existing components is more than adequate to provide a good solution for the nigh-on HD 3D requires for the iPad's 1024x768 screen.

Assuming an IMG connection, Apple could use the same SGX535 as seen in the iPhone 3GS. As that chip has been seen in Intel's GMA 500 chipset running at 400MHz (versus 100MHz in the phone), it would be a more than capable piece of silicon with a significant boost in horsepower over the phone, and indeed the third-gen iPod Touch. Alternatively IMG also offers the SGX540: basically the same tech again, but with twice as many arithmetic logic units.

Adding weight to the IMG connection is the fact that the A4 was designed by Apple's own chip team, the recently acquired PA Semi, but is reputedly being fabricated by Samsung - a long-term iPhone partner. At the same time, at CES, IMG showed a SOC (also fabbed by Samsung) that incorporated a 1.1GHz A8 Cortex and an IMG SGX540 graphics processor. Coincidence, or an off-shoot/sibling of the A4? We'll find out soon enough.

Right now the graphics technology effectively remains an unknown - unlike iPhone there's no mention in the development tools of the hardware being used. All we have to go with regards gaming performance is what we saw at the launch, where titles from Electronic Arts and GameLoft were showcased. The Open GL ES 2.0 titles exclusive to iPhone 3GS where shown running on the iPad, and we also saw titles apparently put together in two weeks especially for the new tablet.

The fact that iPad and iPhone share the same development environment (SDK) is telling. Graphically speaking, it may simply be the case that existing games were recompiled in "iPad mode", effectively reconfigured to run at a higher resolution with the new GPU taking the strain rendering more pixels. It's fair to say that nobody has really put the graphics chip in the 3GS through a thorough workout, but regardless it was disappointing to see Need for Speed: Shift looking so jerky in its iPad incarnation. GameLoft's NOVA looked more impressive though, and showed some interesting ideas for utilising the touch-screen and multi-touch functionality on a much larger display.

Comments from EA on how iPad effectively puts a relatively large HD display right in your face, occupying a great deal of your field of view, should also make for an intriguing sense of immersion we've yet to experience from the existing range of small-screened mobile gaming devices.

In terms of the overall package, iPad seems to be drawing a consensus among commentators. The demonstration of the iPad's eBook system, its interactive newspapers and magazines, its photography, email, browsing and organisational tools all showed the classic level of brilliance we would associate with the undisputed masters of the graphical user interface. In a sense, Apple has gone back to the core philosophy of the netbook: to cut out the OS functionality to the bare minimum, provide the tools that are really needed and then embellish them with a level of user-friendliness that is the company's trademark.

Its timing is exemplary. Since the launch of the original netbooks the nature of the market has changed and, some might argue, not for the better. Small, fast SSDs have given way to the traditional notebook hard drive. Screen size has crept up, and even power-sapping games-capable graphics accelerator chips have been added to some models while the basic, bare OS has been replaced with the more function-rich but battery-draining Windows XP and Windows 7. The ideal 199 RRP has also inflated to the point where there is a worrying amount of overlap between a well-specced netbook and a decent mid-level laptop. Bearing that in mind, Apple's iPad feels like a welcome return to the core ethos of the netbook, expanded to encompass the growing market for media consumption - be it books, movies, music or photos, and backed up with enviable battery life to which few mobile PCs can get close.

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