Re: Real-Mode of Intel processors!!

[Mark Zealey <mark@zealos.org>]

On Fri, Mar 01, 2002 at 01:28:22PM +0530, Ketan Mukadam wrote:

> 
> On Fri, 1 Mar 2002, Thomas Abraham wrote:
> 
> ==>Hi Ketan,
> ==>  This is in response to your query on real mode.
> ==>
> ==>Intel processors can work in two modes. Real mode and
> ==>Protected mode. In real mode, processor works with 16
> ==>bits. All the memory managment and process mangament
> ==>features are turned off in this mode. But in protected
> ==>mode these features are turned on which is very
> ==>essentail for an operating system.

Actually 3 modes, real, pmode and vm86 mode which is a real mode emulation with
all the security of pmode. This is how stuff like dosemu works.

> Actually what you have written, that stuff i already know, but what i wanted to
> know is that where the real-mode is used except bootstrapping. Once ur OS gets
> booted the processor is switched in protected mode.[ This is true of Linux ] Now
> in which situations it returns to real-mode or is it that it never goes into
> real-mode after booting??

Never goes into real-mode, only into vm86 mode

-- 

Mark Zealey (aka JALH on irc.openprojects.net: #zealos and many more)
mark@zealos.org; mark@itsolve.co.uk

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