>On Wed, Jan 06, 1999 at 08:27:29PM -0500, [EMAIL PROTECTED] wrote:
>> virtual mode. aka v86 mode.
>
>Ah. _That_ could be missing...
>
>> I'm sure that was a typo, as virtual memory is a property of the
operating
>> system ;]
>
>Nope. Any reasonable implementation of virtual memory (I'd say _any_
>implementation, but I'm not an internals guru) requires hardware
>support for the page table and page faults. An MMU is a _requirement_
>though it _is_ possible to implement one externally.
I thought this discussion might be confusing some people,
so without really knowing if you already knew this, I'll step
in and attempt a clarification.
Virtual 80x86 mode is hardware support for emulating real mode
in a fully protected "virtual machine" which can host a 16 bit
application running in a 32 bit OS. Linux, Windows 95 and
Windows NT providing 16 bit DOS application support using
this for assistance.
I believe the NS486 is lacking not only this feature but more importantly it
lacks the standard 80486 MMU which you
describe quite correctly.
I just hope that there isn't confusion among readers between MMU with it's
Virtual Memory support and Virtual x86 mode with it's 16 bit application
support.
Warren
