Can a 32 bit OS run in a 64 bit processor?

Question

What's the difference between 32 bit OS and 64 bit OS? Can a 32 bit OS run in a 64 bit processor?

Answer 1

Your question is architecture specific. x64 is essentially an extension to x86 architecture. It supports a 64 bit address space. It provides some new instructions and new registers.

You can run 32-bit x86 Windows on an x64 machine. Note that you can't do this on Itanium 64-bit systems.

Answer 2

A 64 bit processor can run both 32 and 64 OS (at least an x64 can). A 32 bit processor can run only 32 natively.

The difference is mostly about the size of a Pointer/Reference. On 64 bit machines, you can reference an address in a 64 bit address-range (thus giving you 2^64 bytes of memory). On 32 bit you can only address 2^32 bytes (=4 GB). Now if you look at current computers it is obvious why the world is moving to 64 bit: 32 bit can't easily address all the RAM anymore.

On x86 (AMD/Intel) you have additional benefits of 64 bit. The CPU has more registers and thus allows more efficient code.

On other architectures the differences between 64 and 32 bit are less obvious. For example the Nintendo 64 (remember that?) was a 64 bit machine but most of its code was 32 bit. So in that case 64 bit served more as a marketing trick.

Answer 3

Both a 32 and 64 bit OS can run on a 64 bit processor, but the 64 bit OS can use full-power of the 64bit processor (larger registers, more instructions) - in short it can do more work in same time. A 32 bit processor supports only 32 bit Windows OS.

Answer 4

One big difference is that 32 bit does not impress people, but 64 bit does. If you have a really big display, you're golden (with the geeks, anyway).

Of course, it's very unlikely that either of these will help you get your work done any faster, might not even make much of a difference with games for awhile. Rate limiting steps are rarely found in the processor. Don't let that stop you from stimulating our economy, though! ;-)