What is the exact meaning of 'N' bit processor ? , clarification for freescale arch

Question

While reading one Freescale processor manual I stuck somewhere, which specifies that it is a 32-bit processor.

May I know the exact meaning and logic behind that?

Update:

Does it specify its ALU width or its address width or its register width specifically or all of them together is N-bit each.

Update:

Hope you have heard of Freescale processors. I just came across their site which describes one of their latest Starcore-based processor known as SC3850 as a 16-bit processor. As far as I know, it has 32 bit program counters, including ALU, and 40-bit register width and 2x64 bit address bus width. Also the SC3850 can handle SIMD(2) instructions which are of 32 bit or 64 bit.

For more details please go through this link

Answer 1

One of the major reasons you would care about the register width of the processor is performance. Generally doubling the number of bits doubles the rate at which a processor can move data around, and compute. This is why we're not all using 8 bit processors.

The other major reason is address space. A 16 bit program counter limits you to 64k of address space, and a 32 bit counter limits you to 4 gigabytes. The new 64 bit processors make it possible, if all the address lines are present, to support 17,179,869,184 gigabytes of memory.