First, two quotes from my review of the original iPhone:

“The issue is that the iPhone interface is just as responsive as a computer, so you inherently expect the sort of performance you'd see on a notebook and it's just impossible on a device like the iPhone."

“I think overall we need a handful of upgrades to the iPhone alongside 3G; we need a faster processor, possibly more system memory, maybe even faster flash. The MLC flash in the iPhone has absolutely horrendous write speeds compared to SLC, which could be holding the iPhone back a bit. I can see Apple introducing a 3G version in about 12 months, addressing many of these issues at the same time.”

Indeed, 12 months after the launch of the first iPhone - Apple did fix the wireless performance issues with the iPhone 3G. Unfortunately, the hardware remained untouched. All of my other complaints in those two quotes remained open ticket items between Apple and I. In fact, things got worse. Here we have what I wrote at the end of my iPhone 3G review:

“Apple must be wary of the direction the iPhone is headed in. While the UI was absolutely perfect for the phone that launched a year ago, today’s iPhone is hardly the same. With easily over twice as many applications on an iPhone today vs. a year ago, performance and navigation have both suffered. The impact isn’t tremendous, but Apple will have to adjust the iPhone accordingly in order to avoid turning the platform into a bloated, complicated mess.”

Two days ago, Apple announced the iPhone 3GS - designed to address one thing: performance. The other half of my complaint in the conclusion of my 3G review, addressing navigation and UI with the new expanded iPhone platform, isn’t addressed by the 3GS. I suspect that in another year we’ll see that. But today, it’s about hardware.

The Impetus

After yesterday's Pre vs. iPhone 3G battery life article I got a few emails from people very close to the chips used in the iPhone 3GS. A couple of exchanges later and I realized it might be time to go a little deeper with the hardware behind the iPhone 3G, iPhone 3GS and the Palm Pre.

The Original

The iPhone and iPhone 3G use a system on a chip (SoC) from Samsung. The SoC is a custom part and actually has Apple’s logo on the chip. The SoC houses the CPU, GPU and memory for the iPhone.

The CPU is based on the ARM11 core, in specific it is the ARM1176JZF-S. The CPU runs at 412MHz to save power, although the core is capable of running at 667MHz. The ARM11 CPU is a single-issue in-order microprocessor with an 8-stage integer pipeline. It’s got a 32KB L1 cache (16KB for instructions, 16KB for data) and no L2 cache. The ARM11 CPU in the iPhone also has a vector floating point unit, but thankfully the SoC includes a separate GPU for 3D acceleration. You can think of this core as a very high clocked, very advanced 486. And extremely low power. Under typical load, the CPU core should consume around 100mW. By comparison, the CPU in your laptop can require anywhere from 10 - 35W. Idle power is even lower.

Paired with this CPU is a PowerVR MBX-Lite GPU core. This GPU, like the CPU, is built on a 90nm process and is quite simple. The GPU does support hardware transform and lighting but it’s fully fixed function, think of it as a DirectX 6/7 class GPU (Riva TNT2/GeForce 256). Here’s PowerVR’s block diagram of the MBX:

The MBX-Lite in the iPhone shares the same architecture as the MBX but is optimized, once more, for power efficiency and thus is significantly slower.

I don’t have exact clock speed information for the MBX-Lite in the iPhone but I’m guessing around 60MHz.

Coupled with the CPU and the GPU in the iPhone’s SoC is 128MB of DDR memory, all on the same chip. It’s a pretty impressive little package. You get a CPU, GPU and memory all in a package that’s physically smaller than Intel’s Atom.

Now the 486 came out in 1989 and the original 3dfx Voodoo graphics card came out in 1996. The iPhone’s SoC would be ridiculously powerful if it were running the sorts of applications we had back then, but it’s not. We’re asking a lot from this little core and although it has performed admirably thanks to some clever software engineering on Apple’s part, it’s time for an update.

Enter the ARM Cortex A8
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  • Anand Lal Shimpi - Wednesday, June 10, 2009 - link

    In addition to the ARM11 core, I believe the GPU side of tegra does use too much power for something like the iPhone. I can't find detailed specs for NVIDIA's low end Tegra, but Wikipedia lists ~4W for the higher end model - that's simply too much. We need to see values in the mW range.

    Take care,
  • peccavi - Wednesday, June 10, 2009 - link

    From what I gathered, Apple is increasing support for iPhone peripherals. Could this allow for a controller / docking cradle for the iPhone? Imagine 4 buttons and a couple of directional pads on either end of the phone in landscape mode. Would make for a great little gaming unit.
  • eburnette - Wednesday, June 10, 2009 - link

    One thing that wasn't clear from the article is how certain are you about the information? Is it just speculation at this point until somebody gets one and tears it down?
  • Anand Lal Shimpi - Wednesday, June 10, 2009 - link

    I'm very certain. The info comes from sources very close to the licensees for both the CPU and GPU. Without hardware in hand it's impossible to be 100% sure, but what Apple has implied lines up well with what I've been told.

    The ~2x gains in app performance would only come from a faster processor. Apple's options there are to either use a much higher clocked ARM11 or move to the Cortex A8. You can't get 2x out of a 200MHz speed boost to an ARM11 core, so that leaves the A8.

    The graphics side I'm also very sure about, although I can't post why :)

    Take care,
  • psychobriggsy - Wednesday, June 10, 2009 - link

    Thanks for confirming the rumours.

    I think you should point out that the CPU and GPU are actually on the same die, indeed everything apart from the RAM will be on that die. Some parts of the article imply that the CPU and GPU simply share the package, but could be separate dies.

    A little sad that the GPU is the SGX520 - the lowest end, but it's still so much better than the MBX it doesn't matter. Shame you can't snaffle a die shot from Samsung ;) maybe the graphics are by comparison quite large, even considering the A8 with L2 cache.

    The crypto co-processor that's been added is certainly being used, as hardware crypto was mentioned in the keynote. That will aid iPhone SSL web browsing speed I'd hope.

    Also the A9 is out-of-order, so comparable to a Nano, as the A8 is comparable to Atom and the ARM11 is comparable to a very fast 486.
  • Simon F - Wednesday, June 10, 2009 - link

    [quote]Paired with this CPU is a PowerVR MBX-Lite GPU core. This GPU, like the CPU, is built on a 90nm process and is quite simple. The GPU does support hardware transform and lighting but it’s fully fixed function, think of it as a DirectX 6/7 class GPU (Riva TNT2/GeForce 256).[/quote]

    This is not strictly correct. IIRC the MBX model in the iPhone has a programmable vertex shader that exceeds DX8. The pixel pipeline, though, is fixed function. Having said this, I'm not sure if the programmable aspects of the vertex shader are exposed in the iPhone interface.
  • faxon - Wednesday, June 10, 2009 - link

    i have by and large stayed away from apple my entire life, but given their recent innovation on the consumer devices front and their virtual monopoly on the high capacity music players market with the ipod, i have been keeping them on my radar none the less. when a family member picked up an iphone3G when we switched to AT&T for our wireless service, i was actually rather impressed at simply how much better it was than the blackjack 2 i picked up, at just about everything. the only complaint i had was in its texting performance, but with a cloned SIM card i could get around that simply by pulling out my blackjack 2 instead. I have been looking at getting an iphone since i use my phone for mobile browsing excessively, and even using opera the blackjack 2 doesnt come close in ease of use compared to the old iphone on edge. with the new 3Gs also supporting picture texting (a requirement of my GF) i may just look into this if i get the promotion im gaming for by the end of the summer.
  • sxr7171 - Wednesday, June 10, 2009 - link

    I avoided the iPhone for so long and I even bought one to jailbreak and play with, but it wasn't until OS 3.0 that it became my daily phone. The Exchange support on it beats most other smartphones.
  • strikeback03 - Wednesday, June 10, 2009 - link

    I'd say high capacity music players are the only segment of mp3 players where the Ipods are not dominant. The only high capacity models are the classic/video ones, which don't seem to be that popular and don't appear to have been upgraded nearly as recently as the touch and nano.
  • Dennis Travis - Wednesday, June 10, 2009 - link

    Anand, thanks so much for your preview. I can't wait for your review after you get a hold of the phone. I am really interested in battery life. During the keynote I thought they said something about a new battery and that was why more battery life. I guess we will soon know for sure.

    Thanks again!

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