64 Bit Processors in Mobile phones

64 Bit Processors in Mobile phones

Normally in the field of computing, we have made use of 32 bit processors extensively.

Let me explain a little bit about a processor and the bit associated with it.

•    A 32 bit processor has a 32 bit ALU. This 32 bit ALU can perform 32 bit arithmetic and logical computations like adding - subtracting 32 bit numbers or 'AND'ing two 32 bit numbers.

Similarly a 64 bit processor has a 64 bit ALU. This can perform arithmetic operations on 64 bit numbers. If you are supplying 32 bit data to a 64 bit cpu, it is not going to make any difference in terms of processing speed.

My point is, If you are using a 32 bit OS on a 64 bit CPU it is not going to make much of  a difference. On the other hand, if an app is capable of supplying a 64 bit format data, then it would get compiled or it would run considerably faster compared to it's 32 bit counterpart.

Apple A7 Cyclone 

•    A 32 bit processor has 32 bit registers. These registers are used to hold intermediate data during computation process. This works in nice camaraderie along with the CPU to speed up the execution process. There are many registers used to hold intermediate data, which work along with the CPU.

Now, with a 64 bit processor each of these registers can hold 64 bit of intermediate data.

So, suppose there is an app process of 1MB to be executed. Thus a 64 bit processor, can perform 64 bit arithmetic operations on the decoded data and store the intermediate results in  64 bit registers . Thus this 1MB process as it is divided in to 64 bit data streams can be executed much faster compared to 32 bit.

• A 32 bit processor has bus width of 32 bit to transport data. 

A 64 bit processor on the other hand has a 64 bit bus.

Nvidia Tegra K1

So, more amount of data can flow between CPU and different components attached to it. This speeds up processes such as Video decoding, supporting higher class GPUs and 1 more very important thing, probably you have heard elsewhere.

Supporting RAM upto 8GB in size.
32 bit CPU could support 2 power 32 memory locations. Hence, upto 4GB in theory. Whereas, a 64 bit CPU can support 2 power 64 memory locations. Hence, upto 8GB.

64 bit CPUs in mobile computing follow ARM v8 architecture. Till now, Apple A7 and Nvidia K1 CPUs have implemented it.