64-bit

[VoidLogic]

Is there a 64-bit PMode for the new Opertron, and if so is the 64-bit part and more registers the only difference?

[drwatts]

There are actually two 64-bit modes, compatibility (or legacy) mode and true 64 bit long mode.  Many items are activated in 64 bit mode, but the extra memory and related items are avaliable in compatibility mode, which can support either 32 or 64 bit code.  If you want more information, the five architecture manuals are avaliable on AMD's website.  I put in a request and they shipped all five to me for free.  You could technically completely develop a 32-bit OS for Opteron, but it is much better to jump to long mode, and use the extra PAE extensions.  Its a really elegant architecture considering it was built on x86.