The Impact of Larger Memory

Apple doubled memory capacity on the new iPad to 1GB, marking the first time in recent history that Apple's flagship product offers a similar amount of memory to the current crop of high-end Android devices. Apple's iOS can do a relatively good job with limited system memory as it will conservatively unload applications from memory in the event that it needs to free up more space. iOS does not support paging to flash, making DRAM size a hard limit for developers looking to really push the platform.

Apple has always been conservative on DRAM sizing because it's a great way of reducing the BOM (Bill of Materials) cost. If Apple can make up for having less DRAM by being more aggressive in software (read: kicking apps out of memory), it's a tradeoff that makes sense. It's really Apple's foray into gaming that has added pressure to increase memory sizes.

With the move to the Retina Display, the amount of memory needed to store a single frame increases by 4x—from 3MB to 12MB. Assuming two buffered frames you're looking at 24MB of RAM just to smoothly display what you're seeing on the screen.

The bigger problem isn't the frame buffer, but rather all of the other data you need (e.g. level data, textures, etc...). The higher the screen resolution, the more important it is to have higher quality assets in your game. Texture compression can go a long way, but at some point there's simply more data to deal with as game complexity increases. It's not just about the increase in resolution either. As GPU horsepower increases, so will the complexity of what game developers try to build.

While the frame buffer size increased thanks to the Retina Display, total system memory increased by a much larger amount. With 1GB of memory, game developers are now less constrained.

A more immediate benefit is apps and web pages will remain resident in memory longer as you open open up and switch to other apps. For example, on the iPad 2 if I open four tabs in Safari (AT, Engadget, Reddit, and Tech Report), open iPhoto, run Infinity Blade 2 and GTA 3, switching between the latter two will always require a full game reload (as in you see the intro and everything before you pick up where you left off). On the new iPad, with the same setup, I can switch between Infinity Blade 2 and GTA 3 and automatically resume where I last left off thanks to the extra DRAM. You can still create a scenario where even 1GB isn't enough, it's just that the limit is now higher than it was on the iPad 2.

A Word on Packaging & Looking Forward GPU Performance
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  • Steelbom - Thursday, March 29, 2012 - link

    I'm curious why we didn't see any graphics benchmarks from the UDK like with the iPhone 4S review?
  • Craig234 - Thursday, March 29, 2012 - link

    Wow, this is good to buy... 'if you are in desperate need for a tablet'?

    That's a pretty weak recommendation, I expected a much stronger endorsement based on the review.
  • Chaki Shante - Friday, March 30, 2012 - link

    Great, thorough review, thanks Anand et al.

    Given the sheer size of the SoC (like 4x larger then Tegra2 or OMAP4430, and 2x Tegra3), you'd bet Apple has the fastest current SoC, at least GPU-wise.

    This SoC is just huge and Apple's margin is certainly lowered. Is this sustainable on the long run ?

    I wonder if any other silicon manufacturer could make same size devices (not technologically but from a price perspective) and expect to sell them.
  • dagamer34 - Friday, March 30, 2012 - link

    No one else needs to crank out so many chips that are the same. Also, other companies will be waiting long enough to use 28nm, so there's little chance they'll be hitting the same size as the A5X on 45nm.
  • Aenean144 - Friday, March 30, 2012 - link

    Since Apple is both the chip designer/licensee and hardware vendor, it saves them the cost of paying a middleman. Ie, Nvidia has to make a profit on a Tegra sale, Apple does not, and can afford a more expensive chip from the fab compared to the business component chain from Asus to Nvidia to GF/TSMC and other IP licensees.

    I bet there is at least 50% margin somewhere in the transaction chain from Asus to Nvidia to GF/TSMC. Apple may also have a sweetheart IP deal from both ARMH and IMGTEC that competitors may not have.
  • shompa - Friday, March 30, 2012 - link

    @Aenean144

    Tegra2 cost 25 dollars for OEMs and 15 dollars to manufacture. A5 cost Apple 25 dollars to manufacture. By designing its own SoC Apple got 30% larger SoC at the same price as Android OEMs.

    Tegra3 is huge. That is a problem for Nvidia. It costs at least 50% more to manufacture. Nvidia is rumored to charge 50 dollar for the SoC.

    A5X is 50%+ larger then Tegra3. Depending of yields it cost Apple 35-50 dollar per SoC.

    The integrated model gives Apple cheaper SoCs, but also custom designed for their needs. Apple have a long history of Accelerating stuff in its OS. Back in 2002 it was AltiVec. Encoding a DVD on a 667mhz powerbook took 90 minutes. The fastest X86 AMD 1.5ghz it took 15 hours. (and it was almost impossible to have XP not bluescreen for 15 hours under full load). Since 2002 Apple accelerate OSX with Quarz Extreme. Both these techniques are now used in iOS with SIMD acceleration and GPU acceleration. Its much more elegant then the brute force X86 approach. Integrated makes it possible to use slower, cheaper and more efficient designs.
  • shompa - Friday, March 30, 2012 - link

    The A5X SoC is a disaster. Its a desperation SoC that had to be implemented when TSMC 28nm process slipped almost 2 years. That is the reason why Apple did not tape out a 32nm A5X on Samsung. PA Semi had to crank out a new tapeout fast with existing assets. So they took the A5 and added 2 more graphics core.

    The real A6 SoC is probably ready since long back, but TSMC cant deliver enough wafers. The rumored tapeout for A6 was mid 2011. Apple got test wafers from TSMC in june and another batch of test wafers in october. Still at this point Apple believed they would use TSMC for Ipad3.

    ARM is about small, cheap and low power SoCs. That is the future of computing. The A5X is larger then many X86 chips. Technically Intel manufactures many of its CPUs cheaper then Apple manufactures the A5X SoC. That is insane.
  • stimudent - Friday, March 30, 2012 - link

    Products reviews are fun to look at, but where there's a bright side, there is always a dark side. Maybe product scoring should also reflect how a manufacturer treats its employees.
  • name99 - Friday, March 30, 2012 - link

    You mean offers them a better wage than they could find in the rest of China, and living conditions substantially superior to anywhere else they could work?
    Yes, by all means let's use that scoring.

    Or perhaps you'd like to continue to live your Mike Daisey dystopia because god-forbid that the world doesn't conform to your expectations?
  • Craig234 - Friday, March 30, 2012 - link

    I'm all for including 'how a company treats its employees' and other social issues; but I'd list them separately, not put them in a product rating.

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