What are the two main differences between 32-bit and 64-bit architecture?

Answer 1

The principle difference is the amount of data that is processed at one time. A 32 bit processor generally processes 32 bit "chunks" of data at any one time. 64 bit, as you probably will guess, processes 64 bit chunks.

Because more data is processed with 64 bit systems, they run faster than 32 bit systems - although not twice as fast as you might expect (or hope!). That's because processing data is only one thing that a processor has to do - it also makes decisions, moves information around, control peripherals and so on. So 64 bit systems run around 10-15% faster than 32 bit ones.

Answer 2

When you have the smaller 32-bit size, there is more potential for bottlenecks to occur. Bottlenecks slow down your system because one process has to wait for another to finish before it can begin. But if you want to have 64-bit wide tubes, your computer needs to be thinking in 64-bit so your software and hardware all need to support 64-bit.

On a 32-bit operating system, you are restricted to a maximum of 4 gigabytes of RAM. On a 64-bit operating system, you really do not have a limit. Let's look at Wikipedia and find out the maximum amount of RAM for a 64-bit operating system.

The phrase "X-bit" architecture, where the X can be any number (typically 8, 16, 32, or 64 these days) generally refers to two major concepts:

1. The number of bits allocated to storing memory pointers, which influences how much memory the system will support
2. The number of bits used for typical integer calculations

In pretty much all modern computer architectures, both the memory pointer and default integer size are the same, and are where the "X-bit" name comes from.

Thus, a 32-bit architecture uses 32 bits to store memory pointers, which means that it can allocate up to 2^32 bits of memory (or, about 4GB). It also does integer calculations with all numbers stored in a 32-bit wide space. For 64-bit architectures, they have up to 64-bits for memory pointers, resulting in 2^64 bits of memory (about 16 Exabytes); likewise, all integer calculations use registers of 64-bits in size.

Practically speaking, 64-bit computers can thus access considerably more memory than a 32-bit computer (these days, 4GB is hardly enough even for everyday use). A 64-bit computer can also perform large number calculations much faster than a 32-bit one (so, if I'm adding two numbers of 40-bits each in size, I can do it over twice as fast on a 64-bit computer as a 32-bit one), but pay a penalty in memory consumption (thus, programs using a 64-bit architecture tend to be 10-20% larger than ones using a 32-bit architecture).