For chipheads, the big surprise in Apple's iPad announcement was the disclosure that the device uses an "internally designed" processor called the Apple A4. This new 1GHz chip is also likely to appear in the fourth-generation iPhone later this year, although it may be underclocked to 800MHz to save power in the phone.
Another theory is that the A4 instead uses an ARM-designed CPU, such as the Cortex-A9 used in Nvidia's new Tegra 2 and other forthcoming mobile chips. The Cortex-A9 is capable of reaching 1GHz in state-of-the-art 45nm manufacturing technology. If indeed the iPad has a Cortex-A9 CPU, it would be the first mobile product to use that design, beating the Tegra 2 to market by a few months. It would be strange, however, for ARM to work with Apple as the lead customer for its new CPU, knowing that the company would keep the processor to itself. Furthermore, the Cortex-A9 is designed for dual-CPU implementations, and one would expect Apple to brag about this capability if its processor supported two CPUs.
A third idea is that the A4 uses the 1GHz Cortex-A8 CPU known as Hummingbird, which is designed by Intrinsity and manufactured by Samsung. This choice would allow Apple to continue working with Samsung, a long-time Apple supplier that makes the Cortex-A8 processor for the iPhone 3GS. Staying with the Cortex-A8 would also simplify software development. Samsung announced that the Hummingbird CPU had already been validated in silicon last July, putting it on track to be production-ready in time for the iPad launch.
Apple touts the low power consumption of the A4 as enabling the iPad's long battery life. The battery life of the iPad is about the same as that of the iPhone 3GS, but the iPad's large battery has five times the capacity of the iPhone's battery. Most of this extra juice is needed for the big display; the power consumption of the processor has little to do with it.
For 3D graphics, some reports indicate that the A4 uses ARM's Mali engine, but Samsung typically uses Imagination's PowerVR cores, and Apple is an investor in Imagination. From the iPad specifications, we also assume that the A4 includes a video engine capable of decoding H.264 main-profile video at 720p resolution and 30fps. MPEG-4 video is decoded at VGA resolution, a poor fit for the iPad's XGA screen.
Outside of the processor, we expect that the iPad leverages many of the same chips as the iPhone. However, it probably replaces Broadcom's BCM4325 combo chip with the newer BCM4329, which adds 802.11n capability. The iPad has the same cellular specifications as the iPhone 3GS and probably uses the same chips from Infineon, which has supplied all of Apple's iPhone models.
These mysteries should be resolved once the iPad is available. A quick check of the A4's CPU ID and performance characteristics should identify it as a licensed ARM design or a wholly new CPU. If it is the former, Apple is not getting much benefit from designing its own processor chip. --Linley
Additional coverage of this market appears in our recent report "A Guide to Mobile Processors."
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6 comments:
would not make sens that the former PA-SEMI team is building a 64-bit ARM processor, using to the maximum extend the micro-architecture of the former PA SEMI PPC.
In the long run, it is obvious that the x86 will lose the power consumption battle (not all architecture are born equal, and the x86 is clearly a brain damaged one).
To do so (the first 64-bit ARM) would leverage more of the job which was already done at PA.
I don't think smartphones require a 64-bit CPU. Even Atom runs in 32-bit mode in smartphones and MIDs. While a 64-bit CPU would leverage the work done at PA Semi, Apple would not implement that feature unless it was necessary. BTW, given the relative volumes, it is clear that the A4 was designed for the fourth-generation iPhone, and the iPad is coming along for the ride.
When I was thinking of a 64-bit ARM CPU, I was thinking to laptops initially, then a move to Iphone/Ipad.
The fact that 64-bit is not necessary, is maybe not that relevant from a marketing point of view. I would very well imagine Jobs convaincing people that its new gaget is marvellous because it has a 64-bit processor, and that 32-bit is so yesterday ... So I still believe that it is a reasonable scenario. Futur will tell.
Given the extra energy and chip area to drive a 64-bit design with no appreciable gain in this market space, it seems unlikely that they would opt for that choice.
If a design team can handle a 64-bit design, going to 32-bit should not be a problem.
I do not think that Apple could keep the briliant PA SEMI team with project like ME TO ARM SOC (moreover do such mudane tuff, Apple had no need to buy a super star team like PA SEMI). Thus expect something more revolutionary for the comming 18 month. My bets are stil on a multi-core 64-bit ARM variant. But to think that people like Dobberpuhl could stay just to conceive ARM based SOC is just a joke.
@anonymous, Apple doesn't sell devices based upon specs, it sells based upon usability.
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