cpu-registers

64 bit Operating System ?

Hi, 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 Thx ...

How are registers shared among threads?

I know that stacks are per thread, but registers are limited,like on IA32,only 8 registers. So how are registers shared among threads? ...