On Tue, Oct 13, 2009 at 9:47 AM, David W. McSpadden <[email protected]> wrote: > I have read two different articles. One says Windows 8 will be 128 bit and > the other says there is no such thing??
*sigh* :-) The computers we have now aren't "32 bit" or "64 bit" in the first place. When we say "Windows 64-bit ", we really mean the OS kernel is running the processor in Long Mode. The virtual address word is 64 bits, but only 48 bits are actually implemented in the silicon; attempting to go outside that address space faults. With a "32-bit operating system", the OS is operating in i386 Enhanced Protected Mode. The virtual address word is indeed 32 bits wide. With modern processors, though, the physical address word can be 36 bits wide (PAE). Both i386 and x86-64 support integer and floating point math in 128 bit words (SSE, etc.). The I/O pathways in most modern systems are still only 32 bits wide, although some servers have 64-bit PCI slots. PCI-Express is fundamentally serial in nature and doesn't even work that way. The DEC Alpha used a 64 bit virtual address word and 64 bit physical address word, right from the start. There wasn't anything smaller. But the Windows NT code at the time wasn't 64-bit clean. Microsoft thus crafted NT to only use addresses below the 4 GB mark. So the OS ran on 64-bit only hardware, and was thus a "64-bit OS", but still couldn't address more than 4 GB of RAM. So a remark that an OS "will be 128 bit" is absolutely, totally worthless without further clarification. -- Ben ~ Finally, powerful endpoint security that ISN'T a resource hog! ~ ~ <http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/> ~
