The iPhone 6 Review
by Joshua Ho, Brandon Chester, Chris Heinonen & Ryan Smith on September 30, 2014 8:01 AM EST- Posted in
- Smartphones
- Apple
- Mobile
- iPhone 6
A8: Apple’s First 20nm SoC
As has been customary for every iPhone launch since the company began publicly naming their SoCs, Apple has once again rolled out a new SoC for their latest line of phones. With the launch of the iPhone 6 series Apple is now up to their eight generation SoC, the appropriately named A8.
After a period of rapid change with the A6 and A7 SoCs – which introduced Apple’s first custom CPU design (Swift) and the first ARMv8 AArch64 design (Cyclone) respectively – A8 is a more structured and straightforward evolution of Apple’s SoC designs. Which is not to say that Apple hasn’t been busy tweaking their designs to extract ever-improved performance and power efficiency, as we’ll see, but our examination of A8 has not uncovered the same kind of radical changes that defined A6 and A7.
The heart and soul of A8 is as always the CPU and GPU. We’ll be taking a look at each of these individually in a moment, but from a high level both of these are evolutions of their predecessors found in A7. Apple’s GPU of choice remains Imagination’s PowerVR, having upgraded from the Series6 based G6430 to Imagination’s newer GX6450 design. Meanwhile Apple continues to develop their own CPUs and A8 packs their latest design, which is an enhanced version of the Cyclone core first introduced in A7.
Stepping away from the GPU and CPU for the moment, the biggest change about A8 is that it’s smaller. As discovered by Chipworks, A8 is being fabricated on TSMC’s new 20nm process, making the iPhone 6 among the first smartphones to be shipped with a 20nm SoC.
This move to 20nm is not unexpected, but nonetheless it is considerable for a couple of reasons. The first is that this means Apple has moved production over to TSMC’s 20nm HKMG Planar process, making this the first time an Apple SoC has been manufactured anywhere but a Samsung fab. There are numerous possible reasons for this – and not every reason needs to be technical – but from a process development standpoint it’s important to note that over the last few generations TSMC has been the leader among contract foundries, being the first to get new processes up and running for volume production.
| Apple A8 vs A7 SoCs | ||||
| Apple A8 (2014) | Apple A7 (2013) | |||
| Manufacturing Process | TSMC 20nm HKMG | Samsung 28nm HKMG | ||
| Die Size | 89mm2 | 102mm2 | ||
| Transistor Count | ~2B | "Over 1B" | ||
| CPU | 2 x Apple Enhanced Cyclone ARMv8 64-bit cores |
2 x Apple Cyclone ARMv8 64-bit cores |
||
| GPU | IMG PowerVR GX6450 | IMG PowerVR G6430 | ||
This move is also quite considerable because it means for the first time Apple is manufacturing their SoCs on a bleeding edge manufacturing process. Prior to this Apple has been slow to utilize new manufacturing processes, only finally utilizing a 28nm process in late 2013 for A7 over a year after 28nm first became available. The fact that we are seeing a 20nm SoC from Apple at a time when almost everyone else is still on 28nm indicates just how much the market has shifted over the last few years, and how Apple’s SoC development is now synchronized with the very edge of semiconductor fabrication technology.
Finally, the switch to 20nm is interesting because after the last couple of generations being so-called “half node” jumps – 45nm to 40nm to 32nm to 28nm – the jump from 28nm to 20nm is a full node jump (note that Apple didn't ever use 40nm, however). This means we are seeing a larger increase in transistor density than in the previous generations, and ideally a larger decrease in power consumption as well.
In practice TSMC’s 20nm process is going to be a mixed bag; it can offer 30% higher speeds, 1.9x the density, or 25% less power consumption than their 28nm process, but not all three at once. In particular power consumption and speeds will be directly opposed, so any use of higher clock speeds will eat into power consumption improvements. This of course gets murkier once we’re comparing TSMC to Samsung, but the principle of clock speed/power tradeoffs remains the same regardless.
Not accounting for minor differences between TSMC and Samsung, in an ideal case Apple is looking at 51% area scaling (the same design on 20nm can be no smaller than 51% of the die area at 28nm). In reality, nothing ever scales perfectly so the density gains will depend on the kind of I/C being laid down (logic, SRAM, etc.). For the complete chip a 60-70% scaling factor is going to be a better approximation, which for Apple means they’ve picked up a lot room to spend on new functionality and reducing their overall die size.
| Apple SoC Evolution | |||||
| CPU Perf | GPU Perf | Die Size | Transistors | Process | |
| A5 | ~13x | ~20x | 122m2 | <1B | 45nm |
| A6 | ~26x | ~34x | 97mm2 | <1B | 32nm |
| A7 | 40x | 56x | 102mm2 | >1B | 28nm |
| A8 | 50x | 84x | 89mm2 | ~2B | 20nm |
Meanwhile once again this year Apple opened up on die size and transistor counts. A8 weighs in at around 2 billion transistors, as opposed to the “over 1 billion” transistors found on A7. We also have the die size for A8 – 89mm2 – which is some 13% smaller than A7’s 102mm2 die. This makes it clear that Apple has chosen to split their transistor density improvements between adding features/performance and reducing their size, rather than going all-in on either direction.
In the case of using a bleeding edge node this is generally a good call, as Apple and TSMC will need to deal with the fact that chip yields at 20nm will not be as good as they are on the highly mature 28nm process. With lower chip yields, a smaller die will offset some of those yield losses by reducing the number of manufacturing flaws any given die touches, improving the overall yield.
A8 With POP RAM Removed
Moving on, looking at A8 we can see that Apple’s memory subsystem design has not significantly changed from A7. Once again Apple has placed an SRAM cache on the chip to service both the CPU and the GPU. Based on an examination of the die and of latency numbers, this L3 SRAM cache remains unchanged from A7 at 4MB. Meanwhile we also find a series of SDRAM interfaces which drive the A8’s package-on-package (POP) based main memory. Based on teardowns from iFixit, Apple is using 1GB of LPDDR3-1600, the same speed grade of LPDDR3 and capacity that they used for the iPhone 5s. iFixit has found both Hynix and Elpida memory in their phones, so Apple is once again using multiple sources for their RAM.
When we start poking at memory bandwidth we find that memory bandwidths are consistently higher than on A7, but only ever so slightly. This points to Apple having worked out further optimizations to make better use of the memory bandwidth they have available, since as we’ve previously determined they’re still using LPDDR3-1600 speeds.
| Geekbench 3 Memory Bandwidth Comparison (1 thread) | ||||||
| Stream Copy | Stream Scale | Stream Add | Stream Triad | |||
| Apple A8 1.4GHz | 9.08 GB/s | 5.37 GB/s | 5.76 GB/s | 5.78 GB/s | ||
| Apple A7 1.3GHz | 8.34 GB/s | 5.21 GB/s | 5.67 GB/s | 5.69 GB/s | ||
| A8 Advantage | 9% | 3% | 2% | 2% | ||
The Stream Copy score ends up being the biggest gain at 9%. Otherwise the rest of the benchmarks only show 2-3% memory bandwidth increases.
More interesting is memory latency, which shows some unexpected improvements once we get out of the L1 and L2 caches. At both the 1MB – 4MB region of the SRAM and 6MB+ region of main memory, memory latency is consistently lower on A8 versus A7. In both cases we’re looking at latencies about 20ns faster than A7. This identical 20ns gain tells us that that Apple is still doing main memory lookups after the L3 lookup fails, and this in turn means the 20ns gain we’re seeing is due to L3 cache optimizations. We have a couple of ideas for how Apple could have improved L3 latency by nearly 20% like this, but at this time with Apple staying quiet on their architecture like usual, it’s not apparent which of these ideas are the correct ones.
Turning our eyes back to A8 one final time, we find that while a lot of die space is occupied by the CPU, GPU, and SRAM (as we’d expect), there is also quite a bit of space occupied by other blocks Apple has integrated into their design. Without already knowing what you’re looking for these blocks are difficult to identify, but even without being able to do this we have a reasonable idea of what blocks Apple has integrated. Among these we’ll find audio controllers, USB controllers, video encoders/decoders, flash memory controllers, the camera ISP, and of course all kinds of interconnect.
All of these blocks are fixed function hardware (or at best, limited flexibility DSPs), which are equally important to not only the A8’s functionality but power efficiency. By assigning tasks to dedicated hardware Apple does spend some die space on that hardware, but in return these blocks are more efficient than doing those tasks entirely in software. Hence Apple (and SoC designers in general) have a strong incentive to offload as much work as possible to keep power consumption in check. This move towards more fixed function hardware is part of a general “wheel of reincarnation” cycle that has been a constant in processor design over the years, which sees a continuous shift between fixed function and programmable hardware. SoCs, for the most part, are still going towards fixed function hardware, and this should continue for a while yet.
In any case, while we can’t identify individual blocks on A8 we do know that Apple has added a few features to A8 that are present in some form or another among these blocks. New to A8 is some mix of H.265 (HEVC) hardware, which would be necessary to enable the FaceTime over H.265 functionality that is being introduced on the iPhone 6. Apple’s “desktop class scaler” that is used for handling non-native resolution applications and for down-sampling the internal rendering resolution of the iPhone 6 Plus would also be present here.
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CalaverasGrande - Wednesday, October 1, 2014 - link
there is more than one iphone competitor with no micro SD.That is just a silly argument. But you are just arguing silly specs. Apple has always lagged behind the bleeding edge. Both on computers and IOS devices. They throw a few nice flourishes on top such as retina or touch ID, but the underlying tech has almost always lagged behind the bleed edge. As the author calls out.
dmacfour - Wednesday, October 1, 2014 - link
And it's only bad for people that have some sort of instinctual need to be on the bleeding edge.kidsafe - Thursday, October 2, 2014 - link
Are you done?TruthLoader - Thursday, October 2, 2014 - link
Did you really forget to mention one of Apple's new key features, introduced the first time with this new iPhone iteration, a capability prominently displayed by the newiPhone 6+ and best described by the words of Apple's CEO:
Dear iSheeps,
I am delighted you guys already noticed our brand-new "iBend" feature. We have intentionally kept quiet to preserve the big surprise now unveiled on behalf of our beloved
iSheep. Let me share the following core principles, which were of particular importance throughout the design and development process:
1) Enhance our iSheep's ability to enjoy a panoramic perspective, to be able to make "Panoramas" without moving the iPhone or needing any third party software.
2) We wanted to compete with curved screen models form LG, Motorola and Samsung, mainly offered in their domestic markets.
3) This is our answer to the curved screen displays offered by LG and Samsung, especially the new Samsung Galaxy Note Edge and the LG G Flex:
http://www.theverge.com/2014/9/3/6097297/samsung-g...
http://www.theverge.com/2013/10/27/5036288/lg-g-fl...
4) It is our firm belief and intention to surprise Samsung and LG by showing that we are capable of having an edged display in our phones without actually having one, all for
the purpose of trashing their new curved display phones and offering you a new, well hidden, feature.
5) Last but not the least, we want to sell more replacement screens (remember, screen replacement prices were already provided before our new iPhone launch event took place
(in anticipation of it:), of course that's a feature, feel free to exchange displays now:)).
I am sure some of you iTards might be aware of some articles stating that although our new phones cost about 200$ to 250$ to manufacture (now the old ones cost even less),
http://recode.net/2014/09/23/teardown-shows-apples...
http://news.investors.com/technology-click/092314-...
http://www.techtimes.com/articles/16347/20140926/i...
we are selling them at a huge premium, which means we make a lot of money and I get to enjoy a lot of additional bonifications (indeed, my 15th luxury home has an indoor pool filled
with 100$ bills, hence I'm able to take a bath without suffocating).
More money leads to more attractive innovations like this special iBend (Registered Trademark, Patend Pending) feature you guys will be blessed with, as usual.
Soon we will launch a new iDevice with an additional "S" in its name, it will offer a whole plethora of new features you will be able to make use of, like the possibility to to bend it back and forth to form an S shape. ("iS", Patend Pending)
I sincerely believe you iSheeps are happy with our new iBend 6 Plus, however please let me take the opportunity to thank you all for being such a giant hoard of ignorant,
blind and mindless suckers whose whole purpose in life consists of buying our new iDevice/iCrap (Registered Trademark, Patend Pending) for a very high premium while wasting
their valueless time waiting in the iQueue just to brag about which poor soul enriched me first.
Always remember and never forget, the only thing premium about apple is price, everything else pales in comparison.
We Own you.
Yours Sincerely
Tim Crook.
TruthLoader - Thursday, October 2, 2014 - link
I'm terribly sorry I did forget to correct some typos, nonetheless, here we go (corrected version):Did you really forget to mention one of Apple's new key features, introduced the first time with this new iPhone iteration, a capability prominently displayed by the new
iPhone 6+ and best described by the words of Apple's CEO:
Dear iSheep,
I am delighted you guys already noticed our brand-new "iBend" feature. We have intentionally kept quiet to preserve the big surprise now unveiled on behalf of our beloved
iSheep. Let me share the following core principles, which were of particular importance throughout the design and development process:
1) Enhance our iSheep's ability to enjoy a panoramic perspective, to be able to make "Panoramas" without moving the iPhone or needing any third party software.
2) We wanted to compete with curved screen models form LG, Motorola and Samsung, mainly offered in their domestic markets.
3) This is our answer to the curved screen displays offered by LG and Samsung, especially the new Samsung Galaxy Note Edge and the LG G Flex:
http://www.theverge.com/2014/9/3/6097297/samsung-g...
http://www.theverge.com/2013/10/27/5036288/lg-g-fl...
4) It is our firm belief and intention to surprise Samsung and LG by showing that we are capable of having an edged display in our phones without actually having one, all for
the purpose of trashing their new curved display phones and offering you a new, well hidden, feature.
5) Last but not the least, we want to sell more replacement screens (remember, screen replacement prices were already provided before our new iPhone launch event took place
(in anticipation of it:), of course that's a feature, feel free to exchange displays now:)).
I am sure some of you iTards might be aware of some articles stating that although our new phones cost about 200$ to 250$ to manufacture (now the old ones cost even less),
http://recode.net/2014/09/23/teardown-shows-apples...
http://news.investors.com/technology-click/092314-...
http://www.techtimes.com/articles/16347/20140926/i...
we are selling them at a huge premium, which means we make a lot of money and I get to enjoy a lot of additional bonifications (indeed, my 15th luxury home has an indoor pool filled
with 100$ bills, hence I'm able to take a bath without suffocating).
More money leads to more attractive innovations like this special iBend (Registered Trademark, Patent Pending) feature you guys will be blessed with, as usual.
Soon we will launch a new iDevice with an additional "S" in its name, it will offer a whole plethora of new features you will be able to make use of, like the possibility to to bend it back and forth to form an S shape. ("iS", Patent Pending)
I sincerely believe you iSheep are happy with our new iBend 6 Plus, however please let me take the opportunity to thank you all for being such a giant hoard of ignorant,
blind and mindless suckers whose whole purpose in life consists of buying our new iDevice/iCrap (Registered Trademark, Patent Pending) for a very high premium while wasting
their valueless time waiting in the iQueue just to brag about which poor soul enriched me first.
Always remember and never forget, the only thing premium about apple is price, everything else pales in comparison.
We Own you.
Yours Sincerely
Tim Crook
Kidster3001 - Thursday, October 2, 2014 - link
Wow, just wow. I agree with most of what you say but you are just going to start fights the way you put it all down. You're not helping.BTW, you mention iPhone Galaxy. I agree, the new iPhone resembles recent Galaxy phones very much in physical form. You should take a look at the Galaxy Alpha though. It looks almost identical to an iPhone 5 with the chamfered edges. pretty sad imo.
DudeDoe - Monday, October 13, 2014 - link
Not that everyone else have already call it.... But, plain and simple: No one is forced to buy A or B. If you don´t like it, or don´t have the means, don´t.Respect the decision and opinion of the others.
Or as someone else had pointed: A) The ones that have the means, they truly have the choice, they can either buy it (because they like the style, the tech, or simply because of the ´status factor´), or they can buy a ´dumb phone´ instead (because they don´t care, or don´t have the need).
B) The ones that don´t have the means. Well those don´t have much of a choice and have to live with what is possible... and accept that, and not coming after the others because "he/she can´t have what he/she really want"
Musikus - Monday, October 13, 2014 - link
Lots of words to say lots of lies. How much döes Samsung pay for these lies? Shame on you, you have no honour and no guts!Pandian - Tuesday, October 14, 2014 - link
Apple's hardware division - so well integrated with its software division that we do not distinguish the two as we would with most others - makes a strong profit on its devices. Starting with iPhones, iPads, iPods, etc., their profit margin on the hardware seems beyond reason, yet the plastic phones with equivalent or inferior build make MORE profit.None of these companies can make such quality devices without the WTO allowing slave labour in China, India, African nations, etc.,to compete at level terms with the labour force of the "developed" nations; the same WTO contract that USA, China, UK, Germany, India, Brazil, Australia and other nations from every dimension of the social or economic space signed!
That made the 19 year old, 16 hour/day worker from China/India/rest of Asia/Africa AT PAR with highly educated and qualified workers from Germany, UK, USA, India, China, Western European nations, etc., workers who work in less enslaving conditions! If the iPhone 4,5 & 6 series, as well as the HTC, Samsung and such companies' products, were made in Japan, Germany, USA, UK, France, etc., they will cost more than $9000 to $25000 to make! So, the going prices for the hardware, not just from Apple, but the entire spectrum, is a great deal for the consumer.
Apple's software make huge profit - brain power is tough to quantify!
The people who steal our money most are the service providing "middlemen"! That includes the companies that allow us to USE these toys! The phone plans, the billing of both parties for the same call - minutes are erased from the caller and the receiver in the USA for the same call! Not one PAC has been formed to fight this.
These non-producing middlemen include the telephone, cellphone and the CABLE companies! Add the satellite companies if their plans go thru'.
People drill liquid 1m or 2000m from the surface, refine and sell them for great profits, because the fluid powers ours locomotives. The same companies prevent alternate sources of fuel for the same use! We are so used to it that when the new set of companies do the same, we are numb to the stabs!
I pay $250 to $800 upfront for a device in the USA, and use it as long as possible, years! Much more of my money is taken from me in much smaller installments every month, adding up to $240+ per family per month, just for phones! Cable and broadband adds another $200+ in most households! THAT is a car payment!
While the newer smartphones allow me to do more - play more games, be entertained with video of various forms such as games, stupid cats, etc. (paying more there), enjoy the social behaviour of human collective without being social by just staring into a 4-6 inch screen, the phones are much smaller and better than the first simple cellphones! Their primary function is still to be able to make quality phone calls! And, texts, when important. Their super-smart powers are seen when used at trade (stocks), hospitals, and now 24/7 health monitoring! Same device - simple or complex use, still cheap at the physical level; buy it cheaper with a plan that does not suit you, you are shredding your cash.
So, Apple or Samsung can gouge me for 100% profit on their quality hardware! I am bleeding into a shock state from the "nickel and dime" hemorrhaging of my other services - the phone plans, the contracts, the over the limits, etc.! The cable companies lay down the hardware still poorly to supply broadband, and channel programs that they do not create! There goes my money!
MacDaddy100 - Saturday, October 18, 2014 - link
It's obvious you don't have much experience in technology, you can tell you've been sucked into the Android/ Samsung marketing telling you what you need in a phone.It seems you sold on specs and specs only, It's sad that Android phone have to put such large specs, faster GHZ, More RAM just to keep up with the iPhone, depending on which benchmarks you read, at times the iPhone is faster, at times Android is faster, but overall pretty even, that just shows how inefficient Android is, Needs double the specs to keep up.
You obviously like car analogies, Its like you think a 1000hp Ford Focus will out race a 500hp Porsche 911 on a race track, just cramming horsepower doesn't make it a all-around better.
Its amazing how much Android keeps copying iPhone features every single year, And Android profits keep sinking FAST, just look at Samsung's recent quarter, complete backslide.
Why is Android flagship phones still using 20 year old 32 bit technology?
Its amusing to watch Fandroids brag about their pretty dancing wallpapers, can't you see that Googles precious Green Robot and Samsung marketing machine has you sucked in.