Understanding the iPhone 3GS
by Anand Lal Shimpi on July 7, 2009 12:00 AM EST- Posted in
- Smartphones
- Mobile
Putting it in Perspective
Below is a table of the CPUs used in some of the top smartphones on the market, let’s put our newly refreshed knowledge to the test.
| CPU | Issue Width | Basic Pipeline | Clock Speed | |
| Apple iPhone/iPhone 3G | Samsung ARM11 | single | 8-stage | 412MHz |
| Apple iPhone 3GS | Samsung ARM Cortex A8 | dual | 13-stage | 600MHz |
| HTC Hero | Qualcomm ARM11 | single | 8-stage | 528MHz |
| Nokia N97 | ARM11 | single | 8-stage | 424MHz |
| Palm Pre | TI ARM Cortex A8 | dual | 13-stage | 600MHz |
| RIM Blackberry Storm | Marvell ARM11 | single | 8-stage | 624MHz |
| T-Mobile G1 | ARM11 | single | 8-stage | 528MHz |
The first thing you’ll notice is that there are a number of manufacturers of the same CPUs. Unlike the desktop x86 CPU market, there are a multitude of players in the ARM space. In fact, ARM doesn’t manufacture any processors - it simply designs them. The designs are then licensed to companies like Marvell, Samsung, Texas Instruments and Qualcomm. Each individual company takes the ARM core they’ve licensed and surrounds it with other processors (e.g. graphics cores from PowerVR) and delivers the entire solution as a single chip called a System on a Chip (SoC). You get a CPU, GPU, cellular modem and even memory all on a single chip, all with minimal design effort.
A derivative of this is what you'll find in the iPhone 3GS
While it takes ARM a few years to completely architect a new design, their licensees can avoid the painful duty of designing a new chip and just license the core directly from ARM. ARM doesn’t have to worry about manufacturing and its licensees don’t have to focus on building world class microprocessor design teams. It’s a win-win situation for this business.
For the most part, ARM’s licensees don’t modify the design much at all. There are a few exceptions (e.g. Qualcomm’s Snapdragon Cortex A8), but usually the only things that will differ between chips are clock speeds and cache sizes.
The fundamentals of the architectures don’t vary from SoC to SoC, what does change are the clock speeds. Manufacturers with larger batteries and handsets can opt for higher clock speeds, while others will want to ship at lower frequencies. The ARM11 based products all fall within the 400 - 528MHz range. These are all single-issue chips with an 8-stage pipeline.
| iPhone 3G (ARM11) | iPhone 3GS (ARM Cortex A8) | |
| Manufacturing Process | 90nm | 65nm |
| Architecture | In-Order | In-Order |
| Issue Width | 1-issue | 2-issue |
| Pipeline Depth | 8-stage | 13-stage |
| Clock Speed | 412MHz | 600MHz |
| L1 Cache Size | 16KB I-Cache + 16KB D-Cache | 32KB I-Cache + 32KB D-Cache |
| L2 Cache Size | N/A | 256KB |
The iPhone 3GS and the Palm Pre both ship with a Cortex A8. I’m actually guessing at the clock speeds here, there’s a chance that both of these devices run at closer to 500MHz but it’s tough to tell without querying the hardware at a lower level. The Cortex A8 gives us a deeper pipeline, and thus higher clock speeds, as well as a dual issue front end. The end result is significantly higher performance. Apple promised > 2x performance improvements from the iPhone 3GS over the iPhone 3G, such an increase was only possible with a brand new architecture.
I must stress this again: clock speed alone doesn’t determine the performance of a processor. Gizmodo’s recent N97 review complained about the speed of Nokia’s 424MHz processor (rightfully so). The review continued by saying that HTC uses 528MHz processors, implying that Nokia should do the same. The second part isn’t what Nokia should be doing on its $500+ smartphone, what is inexcusable is the fact that Nokia is not using ARM’s latest and greatest Cortex A8 on such an expensive phone. It’s the equivalent of Dell shipping a high end PC with a Core 2 Duo instead of a Core i7; after a certain price point, the i7 is just expected.
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lightzout - Saturday, July 11, 2009 - link
My wife actually offered to give me her 3g if she got the the 3gs but I didnt think it was worth it. She asked me this morning how it was better and I didnt know (didnt admit it of course)Now I want her 3G "free" and she really does need the 3gs since since is always multitasking/social/mail..me, including aim.
I thought the 3gs would have some radical new gps stuff but the compass is not impressive. Nothing to get me geeked on to the tune of $200. For my purposes having the older iphone would make travel and remodeling job estimating easier over my tattered razr.
My media mogul mamacita however needs that sleek new 3gs like yesterday as every gripe she has about the 3g phone seems to have been addressed somehow.
Great write-up!
Only regret is when I saw the new screen and sleek size of the 3gs at the apple store a couple days ago it does screem "arent I beautiful?" but that is what apple does so well right?
MrBowmore - Saturday, July 11, 2009 - link
Give the magic, or hero another chance!Your numbers for those phones are whacked, its faster than the 3G at alot of things. Try to kill all the backgroundapps. (yes, it multitasks)
RadnorHarkonnen - Friday, July 10, 2009 - link
Very good analisys.I was just surprised ARM CPUs still made on 90nm and 65nm. With the performance and power saving 55nm and 45 nm processes i would imagine they would jump the bandwagon fast.
nubie - Thursday, July 9, 2009 - link
Some people can't drop $600 in a lump or $2600 over 3 years on something as stupid as a cellphone. No matter what it can do.Besides the fact that Apple is killing all support for proper hardware acceleration and access to OpenGL 2.0, whatever.
Can we get more Android and G1 coverage? Please?
psonice - Friday, July 10, 2009 - link
Like the guy above said, you buy a phone, you either pay a lot upfront, or you get it with a contract. Either way you'll still need to pay a ton of money each month to for your voice and data. You could get a cheap phone that only makes calls and costs almost nothing, but that's not the same is it?And what's this about apple not supporting hardware acceleration / opengl es 2.0??? Almost everything in the gui is hardware accelerated. And there's very good opengl es 1.1/2.0 support in the sdk, hence the ton of hardware accelerated games. There may not be much supporting es2.0 yet, but that's because the first 2.0 capable device has only just been released.
Affectionate-Bed-980 - Friday, July 10, 2009 - link
You know what? The cost is:$199 up front
$70 / year * 24 months
= $1680 + $199
But let's face it, most of you already have cell phones. A quick look at a WinMo phone like the HTC Touch Pro is $70 / month too at minimum ($39.99 voice + $30 data. Same with a Blackberry.
SO WHY THE HELL ARE YOU COMPLAINING?
So if $1880 is too much for you, don't get a cell phone period.
Stop complaining. The iPhone is actually pretty damn cheap. You're locked in a contract, but even if you had another phone WHY WOULD YOU GO DATALESS?
araczynski - Thursday, July 9, 2009 - link
i'll care about the iphone/ipod when they start sporting VGA screens. if my digital camera can have a 3" 640x480 display, so should these overpriced toys.psonice - Friday, July 10, 2009 - link
Higher res screens look pretty, but 640x480 needs 2x more power to fill than 480x320. The screen is more than acceptable already, so I'd take faster running apps/games and longer battery life over more pixels any day.Kougar - Thursday, July 9, 2009 - link
Thanks for the informative crash course in CPU instructions, that filled in some gaps I didn't understand. It's nice to now understand how some aspects of the design fit into or affect the rest of the design.Unfortunately, you've only drummed up the excitement factor for Intel's Sandy Bridge... from some general info that's been around and based on what you've given it sound like the potential is very much there for some very significant performance jumps. So much for Gulftown's allure!
christinme7890 - Thursday, July 9, 2009 - link
I love the attention to detail when describing the CPUs and the graphics processor and stuff. Very cool. I hate that other people are dissing the iphone hardware. If you don't like Macs rules get a pre. Plain and simple. I for one support these people that want to sell their apps for a good price and are trying to make it big in the dev world. Kudos and I will buy your apps.I will be honest, I am sick of the multitasking argument. You do hit on a point that needs to be addressed imho by Apple and that is that there is no good app for chatting. I really think that Apple needs to include their own IM App that stays on in the background (if you want it to) and collects all your SMS, MMS, IM, facebook, Twitter, etc messages. This would be great. While it would be great I recognize that this would totally sap the power on the iphone. If you had all this info push to your phone, the servers would be constantly sending you messages every second. As for multitasking, I don't really care to have it. There are areas where I wish I had it but it is not necessary. Not to mention that the palm pre has a horrible battery life...plain horrible. I hear people talk like they need 3 backup batteries just to get through the day.
I have noticed myself that the compass is a little sketchy. There was a time on 07/04 that a friend and I were lost in the city walking around and we used my maps app to find where we are and I tried to get the compass to work to make reading the map easy and it wouldn't work. The map wouldn't rotate and it was frustrating. Oh well.
Your review of the camera was spot on. It will never replace my uber camera but when I am out and about doing whatever it does great for quick and easy pics. And the movie functions are awesome as well. Now if only you could cut out middle pieces of a movie. Hopefully soon.
I love the speed of the 3gs. I notice, not tested but notice, a large speed increase and I absolutely love it.
The one major place the 3GS has over the pre is the App store. No company has been able to implement an app store like Apple. I get all my multimedia from one source (itunes) which is great....Movies, podcasts, video, audio, apps, etc...all in one place is the best thing that apple has done in forever. I will not argue prices or app submission ethics because I truly believe that apple keeps the People as their top priority.
Great article.