Re: [LinuxBIOS] Bios "Bible"?

[Peter Stuge]

On Tue, Mar 29, 2005 at 09:29:06PM -0800, Justin Walsh wrote:
> Or what is the definitive Blue Book on:
> Bios in General?
> Bios in particular?

I'm not sure there is one. Traditionally BIOS code seem to have been
a secret well-kept by mainboard/BIOS companies.
> How does one switch a 686 or 786 from native into real mode?
>
> i.e. 286 emulation?

x86 CPUs start up in a backwards-compatible 8086 real mode. Protected
mode is entered by setting bit 0 in the cr0 register, but first some
descriptor tables need to be set up. Switching back and forth
basically is a matter of flipping the PE bit.

//Peter