What we are getting if someone says "my machine is 64-bit computer" . What is the difference between 64-bit computer (I mean the CPU architecture) and operating system (Windows 64-bit OS). Please explain me how these terms are related with processor architecture.
migrated from stackoverflow.com Oct 10 '10 at 8:11
A 64-bit processor is one which handles (or can handle) 64 bits of data in a single operation (for example addition of two registers each containing 64-bit integers, or accessing a memory location via a 64-bit pointer).
A 64-bit operating system is one which is compiled to take advantage of the 64-bit instructions provided by a 64-bit processor and as such will not work on a processor that does not support these instructions. One advantage of 64-bit Windows for example is that it can take advantage of more physical RAM than the 32-bit version of Windows.
Many mainstream 64-bit processors also have 32-bit instructions so that they are able to run either a 32-bit or a 64-bit operating system.
CPU with 64-bit registers can process more data than the 32-bit CPU that is faster than the CPU 16-bit and 8-bit. The more space available in the system CPU registers, the more also the process that can be handled, particularly in terms of system memory