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Inside Apple's iPhone 4S and its A5 CPU: 'S' is for Speed

post #1 of 17
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The voice recognition technology and improved camera in Apple's iPhone 4S are made possible by the custom-built dual-core A5 processor that powers the handset.

Leading up to this Friday's launch of the iPhone 4S, AppleInsider will offer a closer look at some of the features of the next-generation handset. Given that the 'S' in the device's moniker was never officially defined by Apple, we offer five potential definitions. Today: 'S' is for Speed, thanks to the A5 processor.

Fastest phone on the market

Rather than get into technical specifications that are meaningless to most consumers and don't tell the whole story, Apple has not publicly revealed the clock speed or onboard RAM of the A5 processor that is found in the iPhone 4S. Instead, Apple has stated that the A5 is up to two times more powerful than the A4, and offers up to seven times faster graphics.

The A5 already debuted earlier this year in the iPad 2 with a variable clock rate around 1GHz, and 512MB of RAM, but evidence has shown the iPhone 4S processor has some slight differences to allow for improved battery life on the smaller device.

The A4 processor found in the iPhone 4 also had 512MB of RAM, while the A4 in the first-generation iPad had just 256MB. Initial speculation suggested the iPhone 4S would again double the iPad and feature 1GB of RAM, but tests have found it features 512MB, with the CPU clocked at 800MHz.

Of course, the real numbers that matter are benchmarks, and in those tests the iPhone 4S easily tops not only the iPhone 4, but the rest of the high-end smartphone market. AnandTech found that the dual-core A5 processor of the iPhone 4S earned a Geekbench score of 623, compared to a score of 360 for the iPhone 4.



That faster processing power is also evident when browsing the Web. Tests conducted with the iPhone 4S showed the hardware achieves a score of 89,567 in BrowserMark testing. That's 74 percent better than the existing iPhone 4, and higher than the Motorola Atrix 4G's score of 53,576.

In terms of graphics capabilities, the difference is far more striking. GLBenchmark 2.1 tests verified Apple's claims that the A5 offers graphics processing up to seven times faster than the A4 processor found in the iPhone 4.

iPhone 4S CPU specs via Macotakara.

For example, in the GLBenchmark 2.1 Pro Offscreen test, the iPhone 4S and its SGX 543MP2 GPU earned a score of 122.7, while the iPhone 4 and its SGX 535 garnered just 15.3. The iPhone 4S score was also well ahead of the Samsung Galaxy S II, which earned 67.1, and the LG Optimus 3D, with a score of 42.6.

Delving back into the technical side, the iPhone 4S A5 has a BUS frequency of 200MHz, a L1 cache size of 32KB, and L2 Cache of 1024KB. In the iPad 2, the A5 BUS speed is 250MHz, while the A4 BUS speed of the iPhone 4 is 100MHz.

Console-quality graphics in your pocket

One of the greatest strengths of the A5 processor is its graphics processing capabilities. To highlight that, Apple at its iPhone 4S unveiling showed a glimpse of the upcoming title "Infinity Blade 2," the sequel to the best-selling iOS game from Chair Entertainment and Epic Games.

Epic is best known for making PC and console titles like "Gears of War" and "Unreal Tournament," but last year's release of "Infinity Blade" flexed some of the processing muscle of Apple's custom processors. But the A5 found in the iPhone 4S represents another huge leap forward for mobile gaming, Donald Muster, Chair Entertainment creative director, said in an interview with Eurogamer.

"As we've been working with Apple the last few weeks, I've had the opportunity to use the iPhone 4S quite a bit and, man, it's awesome," he said. "That A5 chip is pretty incredible. Having that much power in a device that small -- really, there's a lot we can do with it."

With his team hard at work on "Infinity Blade 2," Mustard noted that the iPhone 4S will be capable of creating dynamic shadows on characters, and will feature dynamic light rays that shine through objects. He said the title looks "unbelievable" on Apple's next-generation handset.



"I'm still shocked that, with the iPhone 4S, I'm literally running around with a 1080p video camera in my pocket, with an 8-megapixel camera, 64GB of hard drive space and an A5 chip with 512MB of memory. This is a really powerful computer, right? That's going to allow us to do some really cool stuff for gaming."

"Infinity Blade II" will arrive on Dec. 1, 2011, and will be available only on Apple iOS devices.

Other third-party developers are also planning to take advantage of the added computing power in the iPhone 4S. Firemint's forthcoming "Real Racing 2" update will add 4-person split-screen gaming support to the iPhone 4S via AirPlay and the Apple TV.

The multiplayer functionality, demoed last week by the developer, requires the A5 processor found in the iPhone 4S and iPad 2. With it, the device will be able to host a game, and friends with compatible iOS devices can connect to the host, who will then stream the game data via AirPlay to the Apple TV.

This will allow up to four iOS devices to play a game on a big-screen 720p HDTV, as users steer their virtual vehicles with an iOS device. Using the A5 processor, developers will be able to bring console-style and quality gaming to the iPhone 4S.



8MP camera & Siri: Powered by iPhone 4S & A5

The faster speeds of the A5 CPU also allow for greater functionality on the iPhone 4S, with features that Apple says are not possible on previous-generation iPhone hardware. One software addition, already highlighted in the "Inside Apple's iPhone 4S" series, is Siri voice recognition.

With the additional power of the A5, the iPhone 4S and Siri will allow users to use their voice to execute tasks or obtain data. Siri allows users to dictate a message, find local restaurants, add or change calendar events, and even find information like weather or gas prices at in a specific town.



Apple has said that Siri was developed alongside the A5-powered iPhone 4S, and the feature even relies on a data connection to Apple's servers for it to function.

The new processor also promises to greatly improve picture taking abilities with the iPhone 4S. Specifically, the added power is said by Apple to result in a blisteringly fast time to shoot, one that is claimed to be the fastest in the smartphone industry with "zero shutter lag."

While the camera itself has improved hardware for higher quality pictures, the A5 does more than process larger 1080p video and 8-megapixel photo files. The A5 processor also exclusively offers face detection when shooting still images, which allows the iPhone 4S to detect up to 10 faces in a single photo.



With face detection, the iPhone 4S focuses on the most prominent face in a frame. The A5-powered system automatically balances exposure for the picture, resulting in improved picture quality.

Another addition new addition to the iPhone 4S is image stabilization when shooting 1080p video. Utilizing the A5 processor and the handset's gyroscope, the upgraded smartphone does real-time image stabilization when shooting video, resulting in less shakiness in a recording.

For more, see the previous installments of AppleInsider's "Inside Apple's iPhone 4S series:" 'S' is for Shutter, and 'S' is for Siri voice recognition.
post #2 of 17
'S' is for Siri
Citing unnamed sources with limited but direct knowledge of a rumoured device - Comedy Insider (Feb 2014)
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Citing unnamed sources with limited but direct knowledge of a rumoured device - Comedy Insider (Feb 2014)
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post #3 of 17
The PowerVR SGX543MP2 GPU is class leading. Hands down, no doubt about it. 2x more than anything currently on the market.

The dual-core A9 CPU is really good. But it is still at ~800 MHz. Fortunately, Apple does an awesome job of optimization their APIs and developers do a great job utilizing and optimizing their apps. But the OMAP 44x0 and Exynos processors are basically equivalent A9 cores, and a lot of those ship at higher clock rate. So, they should have higher raw CPU power.

There will be benchmarks that'll show OMAP, Exynos, Tegra, and even Snapdragon being faster in CPU.

This doesn't matter all that much in the grand scheme of things though. It was very important shipped a competitive SoC for their 2011 hardware, and they did that. Hope they repeat next year, and the year after, and the year after that year and so on.
post #4 of 17
S is for Steve.
post #5 of 17
Quote:
Originally Posted by Eriamjh View Post

S is for Steve.

Nope.
Citing unnamed sources with limited but direct knowledge of a rumoured device - Comedy Insider (Feb 2014)
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Citing unnamed sources with limited but direct knowledge of a rumoured device - Comedy Insider (Feb 2014)
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post #6 of 17
So much for all the tech-spec'ers, anal-ysts, hedge fund managers, day traders, and marketing geniuses who declared iPhone 4S dead on arrival! Gawd, but I hate "experts"! Apple has a true tiger by the tail here; just hope they can make enough of them to make Q1/2012 the most spectacular earnings period in the history of technology!
post #7 of 17
The Droidtards say that Google's Nexus Prime will be able to run circles around the iPhone 4S, have a better camera, get better battery life and cost much less than the iPhone 4S. Tech-heads and the Wall Street pundits claim that they won't be disappointed in the Nexus Prime because it can do everything they expect a modern smartphone to do and all the things the iPhone 4 can't do. I'm not sure how Google is going to manage all those features but maybe they have some tricks up their sleeves with Android OS 4 (Ice Cream Sandwich). I wonder if Google has that 1.8 GHz processor (Tegra 3??) in the Nexus Prime that's also coming to the Samsung Galaxy SIII. I thought that processor wasn't ready yet in quantity.
post #8 of 17
Quote:
Originally Posted by Shrike View Post

But it is still at ~800 MHz. Fortunately, Apple does an awesome job of optimization their APIs and developers do a great job utilizing and optimizing their apps. But the OMAP 44x0 and Exynos processors are basically equivalent A9 cores, and a lot of those ship at higher clock rate. So, they should have higher raw CPU power.

Because Apple writes the OS and designs the A5, they can put specialized processors on the chip to handle certain tasks that can be offloaded from the main CPU. For example, the A5 contains an ISP (image signal processor) that used for real time face detection and image stabilization among other things.

I'm sure as they continue to design subsequent generations of the chip, they will add more of these co-processors. It's because of this, I believe Apple may not move to a quad-core ARM for the A6, but rather stick with dual-core and give it a speed bump.
Disclaimer: The things I say are merely my own personal opinion and may or may not be based on facts. At certain points in any discussion, sarcasm may ensue.
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Disclaimer: The things I say are merely my own personal opinion and may or may not be based on facts. At certain points in any discussion, sarcasm may ensue.
Reply
post #9 of 17
Quote:
Originally Posted by VinitaBoy View Post

So much for all the tech-spec'ers, anal-ysts, hedge fund managers, day traders, and marketing geniuses who declared iPhone 4S dead on arrival! Gawd, but I hate "experts"! Apple has a true tiger by the tail here; just hope they can make enough of them to make Q1/2012 the most spectacular earnings period in the history of technology!

You DO realize that Android is not yet optimized for Multi-core yes?

What's next?

Diesel optimized vs non Diesel Optimized?
Energy optimized vs non Energy optimized?

You can brag about it if you need to AFTER 4.0/2.4 is released and we see benchmarks on an equal level. Until then the tests are nothing but talk. Test them on fair grounds, otherwise the benchmarks are invalid.
post #10 of 17
Quote:
Originally Posted by Constable Odo View Post

The Droidtards say that Google's Nexus Prime will be able to run circles around the iPhone 4S.

Grow up and stop calling them that. Heck, a lot of those Android phones lag when you swipe the bloomin' home screen.
Citing unnamed sources with limited but direct knowledge of a rumoured device - Comedy Insider (Feb 2014)
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Citing unnamed sources with limited but direct knowledge of a rumoured device - Comedy Insider (Feb 2014)
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post #11 of 17
"S" is for Sorry... iPhone 5 case builders we screwed with disinformation.

Life is too short to drink bad coffee.

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Life is too short to drink bad coffee.

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post #12 of 17
Quote:
Originally Posted by Jexus View Post

You DO realize that Android is not yet optimized for Multi-core yes?

What's next?

Diesel optimized vs non Diesel Optimized?
Energy optimized vs non Energy optimized?

You can brag about it if you need to AFTER 4.0/2.4 is released and we see benchmarks on an equal level. Until then the tests are nothing but talk. Test them on fair grounds, otherwise the benchmarks are invalid.

Right, because it's Apple's fault Android isn't optimized for multi-core processors and it's never fair to compare current products against current products. Much better to compare against some future, not yet delivered product. In the meantime, the best thing to do is to declare the undelivered product better.

Of course, iOS6 and the next iPhone will smoke these Android phones you're talking about, so it won't be fair to compare 4.0/2.4 to iOS5 on iPhone 4S. Forget the fair grounds, test them at the circus.
post #13 of 17
Quote:
Originally Posted by Constable Odo View Post

The Droidtards say that Google's Nexus Prime will be able to run circles around the iPhone 4S, have a better camera, get better battery life and cost much less than the iPhone 4S. Tech-heads and the Wall Street pundits claim that they won't be disappointed in the Nexus Prime because it can do everything they expect a modern smartphone to do and all the things the iPhone 4 can't do. I'm not sure how Google is going to manage all those features but maybe they have some tricks up their sleeves with Android OS 4 (Ice Cream Sandwich). I wonder if Google has that 1.8 GHz processor (Tegra 3??) in the Nexus Prime that's also coming to the Samsung Galaxy SIII. I thought that processor wasn't ready yet in quantity.

Step right up...
post #14 of 17
Quote:
Originally Posted by mstone View Post

"S" is for Sorry... iPhone 5 case builders we screwed with disinformation.

haha.
Citing unnamed sources with limited but direct knowledge of a rumoured device - Comedy Insider (Feb 2014)
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Citing unnamed sources with limited but direct knowledge of a rumoured device - Comedy Insider (Feb 2014)
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post #15 of 17
Quote:
Originally Posted by mjtomlin View Post

Because Apple writes the OS and designs the A5, they can put specialized processors on the chip to handle certain tasks that can be offloaded from the main CPU. For example, the A5 contains an ISP (image signal processor) that used for real time face detection and image stabilization among other things.

All of the SoCs have image processors and video sub-processors. It may be the ISP in the A5 is faster, who knows. It's likely that Apple does a better job of taking advantage of it.

Quote:
I'm sure as they continue to design subsequent generations of the chip, they will add more of these co-processors. It's because of this, I believe Apple may not move to a quad-core ARM for the A6, but rather stick with dual-core and give it a speed bump.

Yes, Apple will be fine with a going dual core for awhile. If they use the Cortex-A15 architecture in the Apple A6 SoC, they'll be set.
post #16 of 17
Quote:
Originally Posted by Jexus View Post

You DO realize that Android is not yet optimized for Multi-core yes?

The javascript benchmarks (Sunspider and Browsermark) aren't multi-threaded. They only test the performance of one-core executing javascript code. So, they are an indicator of how well the platforms run webapps and javascript heavy websites.

These benchmarks are heavily dependent on the just-in-time compilers in Safari and Android's default browser. So, when Android 4.0/ICS rolls around, these benchmarks should pull even again or even leapfrog as javascript performance has leap-frogged with every iteration of the native JIT compiler.

It has nothing to do with being optimized for multi-core. There's nothing that Google can do that make it's platform benefit from SMP. Each and every app has to be re-architected to take advantage of multi-core, and only a small subset can really take advantage of it.

Quote:
You can brag about it if you need to AFTER 4.0/2.4 is released and we see benchmarks on an equal level. Until then the tests are nothing but talk. Test them on fair grounds, otherwise the benchmarks are invalid.

It is fair grounds. iOS5 and iPhone 4S is available now. Nexus Prime/Droid Prime, and ICS aren't available. When they become available, the comparisons will be done again. This shouldn't come as surprise to you are be an affront to your ego. This happens on a monthly basis in the Android world with new hardware are benched against old.
post #17 of 17
"Apple has said that Siri was developed alongside the A5-powered iPhone 4S, and the feature even relies on a data connection to Apple's servers for it to function."

So if I want to use Siri, I have to have mobile data turned on? Even if I don't ask it to search the web, but just to search stuff on the phone itself, and maybe make a calendar entry?

That's an inconvenience.
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