CODEWITHSUNDEEP
cpu-architecture
Renjith G
Renjith G

Reputation: 4888

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

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

Upvotes: 8

Views: 8057

Answers (3)

mP.
mP.

Reputation: 18266

Firstly i dont have a definitive answer but i would guess that 8 being a power of 2, is an important factor. Being a power of 2 also means that certain optimisations may be performed by dividing the 8 bits into groups which also means lookup tables can be used for certain operations. 8 bits in the past was also the perfect size when dealing wiht plain old ascii characters. I can imagine that using 5 bit bytes and encoding a string of ascii characters across memory would be a pain.

Upvotes: 1

Mike Warot
Mike Warot

Reputation: 349

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.

Upvotes: 2

Escualo
Escualo

Reputation: 42082

Please check out the Wikipedia entry on 32-bit processors, from the entry:

In computer architecture, 32-bit integers, memory addresses, or other data units are those that are at most 32 bits (4 octets) wide. Also, 32-bit CPU and ALU architectures are those that are based on registers, address buses, or data buses of that size. 32-bit is also a term given to a generation of computers in which 32-bit processors were the norm.

Read and understand the article - then the answer for N will be obvious.

Upvotes: 0

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