IPhone 5s: benefits of 64 bit processors if no more than 4 GB of RAM

64-bitcpuiphonememory

My understanding is that the (main) reason of having a 64 bit processor, is to be able to use more than 4 GB of RAM.

In PCs, it is now very common to have more than 4GB of ram, and to really be able to use such ram, you NEED a 64 bit processor.

But for a smartphone, which (afaik) doesn't have more than 4GB of ram, what's the point? what is the benefit?

What kind of apps benefit from it that will really make a difference ?

Specific examples of apps taking advantage would be nice.

Do final users will even notice a difference? Or is it just a marketing strategy?

Note, i know a similar question has been answered here: https://superuser.com/q/56540/152803
but in this one i ask specifically for smartphones, that one is focused on Intel/AMD architecture. Besides, that answer is now more than 4 years old…

Best Answer

My understanding is that the (main) reason of having a 64 bit processor, is to be able to use more than 4 GB of RAM.

Well, everything is 64 bits wide in a 64 bit CPU. For one, computation involving large numbers is more efficient.

ARM introduced a few changes and improvements in the move to 64-bit.

  • All 64-bit ARM CPUs have built in floating point.

  • Quite a few things were simplified, making it easier for compliers to create more optimized code.

  • The SIMD/floating point unit has more registers. This means more data can be processed in operations that use SIMD (like media decoding) or floating point (anything with 3d graphics).

  • It also has a few built-in instructions for cryptography.

Reference.

But for a smartphone, which (afaik) doesn't have more than 4GB of ram, what's the point? what is the benefit?

This is true now. I'd bet in 3-5 years it won't.