Ars Technica:
The only thing that most people will need to know about Apple’s A9 is that it’s a whole lot faster than last year’s A8. But for those of you who are more interested in chip design, Chipworks has unearthed an interesting tidbit: there are two different versions of the A9 chip, one manufactured by Samsung and another by Taiwan Semiconductor (TSMC). Most interestingly, Samsung’s version (the APL0898) has a slightly smaller footprint than the TSMC version (APL1022).
There have long been rumors that Apple was dual-sourcing the A8 from Samsung and TSMC, but this is the first visual proof that we’ve seen of the practice. iPhone and iPad processors up to and including the A7 were all made by Samsung.
This is really “inside baseball” for a lot of folks but it does beg the question of why is Apple doing this? To keep Samsung “honest”? Or are they prepping TSMC to take over chip design?
If I understand correctly Apple designs the chips themselves. This is just fabricating. Why would you want multiple sources? So long as costs and quality are not different, why WOULDN’T they want multiple sources?
The CPU is such a critical piece, that if one supplier has problems, having a second one who can step up and increase production ASAP without having to start from square one is important.
It could be the difference between a phone being supply constrained at launch or a delayed launch, if such a problem crops up. Especially at the quantities that Apple deals with.
Right! Very important distinction: TSMC/Samsung are fabricating the chip, not designing it. These are immensely different specialties. Apple is painting a picture with billions of details; Samsung/TSMC are making copies of it that are ~100mm square.
But the issue here is that the footprints and ergo the designs are different. Who’s responsible for the difference? It is possible that the TSMC version had to be different to suit their manufacturing process.
Yes. The “designs” are actually probably quite a bit different.
Apple’s original source code (RTL) for the processor could be the same or have minor differences between the two versions, but the blocks used to implement the design (standard cells) are typically provided by the foundary or at least designed very closely with them. So Apple would have had to synthesize / verify / test / tweak one design in Samsung’s process and standard cell library and do that all again for another in TSMC’s process/library. This is no simple task and can take weeks/months of work depending on the performance and power targets after the functionality of the processor has been finalized. Which makes this all the more impressive for Apple to have pulled off with seemingly close enough results that they use them completely interchangeably.
Apple no doubt spent a lot of money in engineering man-hours to pull this off, so this isn’t something they’d do on a whim. I think it’s been obvious for years that they’ve been itching to break their dependence on Samsung’s fabs. This is a huge step in that path.
On second reading of Chipworks article, it’s clear (to me) that Samsung is making A9 for iPhone6s and TSMC for iPhone6s+. Chipworks presumes the two chips are the same because there is no discernible performance difference. But with everything larger, it makes sense that SoC for iPhone6s+ needs to be faster (and larger) in order to maintain the same performance as iPhone6s. Ergo, TSMC is making a slightly different (and larger) CPU than Samsung for a larger phone.
“why is apple doing this?”
Because for the first time in the history of the Iphone, they are using cutting edge fabs to make the chips. Which means there’s the potential for problems and slowdowns as the fab works out the kinks in a brand new process. So they double sourced the chips just to be safe.
Always before, they were using mature process tech, but now they’re on the same bleeding edge that has borked Intel’s CPU release schedule.
no, they found the different SOC chips in “two otherwise identical phones”.
If only their margins weren’t so small and volatile, companies like TSMC might make for better investments.