PAE (Physical Address Extension) expands the _physical_ address space to > 32 bits, but the _virtual_ address space stays the same at 32-bits, and the virtual address size is what I mentioned as qualifies the processor as 32-bit or 64-bit. 1. Addressable physical memory / physical address size does not decide whether a processor is 32-bit / 64-bit, there is no processor (AFAIK) which can address 64 bits of physical memory. I suppose sizeof(void*) gives you the size of the _virtual_ address, so yes, I suppose that should be 64 bits on a 64-bit processor (and using a 64-bit compiler) 2. Register size does not decide whether a processor is 32-bit / 64-bit. C On Thu, Oct 22, 2009 at 10:05 PM, Rajat Jain <Rajat.Jain@xxxxxxxxxxxx> wrote: > > Hi, > >> 1. The size of the processor's internal address bus (virtual address >> space) is what qualifies it as a 32-bit / 64-bit processor. > > Well, in that sense, isn't Pentium a "36-bit" processor (since it gives > the option of PAE to use 64 GB of memory - it must be having atleast 36 > address lines)? > > On this topic and in this thread, we have had following responses to the > question on what is called a 32-bit or 64-bit processor: > > 1) Addressable Physical memory (=sizeof(void*)) > 2) Register Size (=instruction size) > > Are the above two independent of each other? If yes, then how do we > deine a processor as 32-bit / 64-bit? > > Thanks, > > Rajat > > -- To unsubscribe from this list: send the line "unsubscribe linux-newbie" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.linux-learn.org/faqs
