BIOS Program

[ACM]

Do BIOS routines run in protected mode or Real Mode. If they run in real mode (which is likely the case for compatibility with DOS) then what happens when Windows 95 or later (which run in protected mode) tries to access a BIOS routine? I would imagine that it can’t change to real mode while Windows is running, or it would stuff up the memory boundaries etc.

[Tim M]

What "BIOS routines" are you referring to? If your talking about the interrogation of devices, this happens during the POST at bootup (relatively speaking, way before any operating system is introduced). It is the operating system that determines real or protected modes.

[Cricket]

The BIOS is actually a very basic operating system (hence Basic Input/Output System) that does it's thing right at boot up (it "boots" the system). It checks to see what's in the computer, determines and sets certain parameters and then hands this information over to the main operating system.

I don't believe the main operating system ever tries to access the BIOS once the information has been handed over (I don't see why it would since Windows "knows" what the BIOS "knows" after the "handoff").

The only time I know you might try to access the BIOS while in Windows is if you're updating the BIOS with some of the newer flash utilities that can work from Windows.

Cricket