The future of Apple's A series chips: The Cortex A7

[chrmjenkins]

At the ARM A7 event today, ARM unveiled a new superscalar architecture completely compatible with with ARM's latest instruction set, utilized by the A15.

What's special about this core is that its intended to be able to handle all of the functions your normal high end smartphone would, but at a much lower power cost than high end A9 or A15 cores.

It does this by having a much simpler architecture (which makes it slower). This is what is called heterogeneous computing, and Nvidia is already at work with it on their "Kal-el" (Tegra 3) chip, but they do it by having a fifth Cortex A9 core that is manufactured on the same die with a lower power process.

What this could mean is a big savings in power because a vast majority of the tasks we ask our phones to do (get notifications while it sleeps, check e-mail) are not demanding and can get by on little CPU horsepower. It's only the few times when we're switching between browser tabs or playing games that we really utilize the CPU.

Con incidentally, since ARM doesn't expect this design to show up on market until end of next year (in 40nm iteration), it's likely we won't see the A7 in an apple design until the A7. I can't imagine apple not wanting to include this processor given their laser focus on battery life in their smartphones.

The real question is if this means they hold off from implementing A15 cores in the A6 because of the A7.

http://www.anandtech.com/show/4991/...dualcore-more-power-efficient-highend-devices

 

[chrmjenkins]

I'm going to bump my own thread with another article on the subject and to make sure more people see it because at some point the discussion for A6 and iPad 3 will reach a fever-pitch.

http://www.wired.com/cloudline/2011/10/arms-cortex-a7/

 

[paulrbeers]

I love what ARM has done with the cortex A7 just like (as stated) what Nvidia is doing with the Kal-El chipset (and their 5th core). Creating "secondary" low power processors that do the basics, it could really save quite a bit of energy. It will be interesting to see how easily the chips switch back and forth (i.e. will we feel a "hestitation" by our devices). Most likely there won't be any hesitation, but it'll be interesting to see how well this works. I will also be curious to see how big the dies will end up since there will be 4 cores instead of two (the two low power ones will be probably pretty small, but still). The idea is definitely solid.

 

[chrmjenkins]

I love what ARM has done with the cortex A7 just like (as stated) what Nvidia is doing with the Kal-El chipset (and their 5th core). Creating "secondary" low power processors that do the basics, it could really save quite a bit of energy. It will be interesting to see how easily the chips switch back and forth (i.e. will we feel a "hestitation" by our devices). Most likely there won't be any hesitation, but it'll be interesting to see how well this works. I will also be curious to see how big the dies will end up since there will be 4 cores instead of two (the two low power ones will be probably pretty small, but still). The idea is definitely solid.

Power gating and dynamic clocking isn't something new to CPUs, so you're already witnessing all the hesitation you're going to see. For instance, can you tell when your iPad 2 or iPhone 4S activates the second CPU core?

The good thing is that the difference between the A7 and A15 is non existent to the OS, the OS simply tells the SoC how much power it needs and then the A7 or A15 is used.