Also how was the move to 32-bit done?
General-purpose register size was increased to 32 bits, as well as stack-pointer register size, index register size, and instruction-pointer register size. This allowed for intrinsic operations on 32-bit integers and access to a 32-bit address space.
Segment descriptor format was expanded to allow access to up to 4GB of linear address space.
Two segment registers ("FS" and "GS") were added to the original four segment registers. Segment registers were left as 16-bit, as they have been since the 8086, but the values stored in segment registers came to have different meaning.
A new "protected mode" was introduced, where the default operand size was 32 bits. (80286 had protected mode, btw, but was limited to 16-bit operands and 16MB of address space)
About the same time, the FPU was updated to allow better parallelism with the integer unit, as well as intrinsic instructions for trigonometry and logarithms. By default, the system still booted up in ye olde 16-bit, non-protected mode for the sake of compatibility; it was up to the operating system to switch the CPU to 32-bit protected mode.
On the software side, we started seeing 32-bit DOS Protected Mode Interface (DPMI) apps for MS-DOS. Most were using the DOS/4GW stub, a rudimentary DPMI layer provided by Watcom with their C/C++ compiler. Windows 3.x began supporting some 32-bit features, and Windows NT 3.51 shipped with 32-bit protected mode support. Finally Windows 95 was shipped with full (if somewhat buggy) 32-bit protected mode support. The 32-bit Windows API ("Win32") got back-ported to Windows 3.1 as the Win32s add-on. The rest is history.
Basically AMD is doing the same thing with the Hammer.
So far, it's confirmed that Microsoft <i>is</i> developing a 64-bit Windows for Hammer. It's been on some Hammer demo systems, so it exists. The question is, how available will this be to consumers? Will it be like Windows XP IA-64, available only to specific customers with specific requirements? Remember, the 386 was released some time in '91 or '92, and it took three years for a fully 32-bit consumer O/S to ship (NT 3.51 was not readily available to consumers).
<i>I can love my fellow man...but I'm damned if I'll love yours.</i><P ID="edit"><FONT SIZE=-1><EM>Edited by kelledin on 06/25/02 04:53 PM.</EM></FONT></P>