Shutting down the computer

[srg_13]

Hi,
How can you turn off a computer from protected mode in C?

Thanks,

Stephen

[Brendan]

Hi,

How can you turn off a computer from protected mode in C?

There's 3 options - APM, ACPI and direct hardware/IO instructions.

For APM there's a protected mode interface (16 bit and/or 32 bit) that's supported by some BIOSs, but not all. This option probably can't be done with C alone.

ACPI is an overcomplicated mess, requiring an interpretter for it's own OOP language (AML). It should be possible to do this all in C though.

Direct hardware/IO depends on the motherboard/chipset, so you'd heaps of "motherboard drivers" - one for each motherboard.

Then there's computers that lack the needed hardware, and therefore don't have any method of turning the power off (e.g. Pentium and older computers).


Cheers,

Brendan

[srg_13]

For APM there's a protected mode interface (16 bit and/or 32 bit) that's supported by some BIOSs, but not all. This option probably can't be done with C alone.

Thats ok, I can use NASM code as well.

[aladdin]

There is also the "Power button" method witch work on all computers

[smiddy]

There is also the "Power button" method witch work on all computers

Yeah, but the trick is to get the software to push the button. ;D

[AR]

You can also reprogram what that button does using ACPI (not sure about APM) so it could open the painting program or some other weird thing instead...

[GLneo]

hi,

if it helps anyone here is a reboot

Code: Select all

void reboot() 
{
    volatile unsigned char good = 0x02;
    while ((good & 0x02) != 0)
        good = inportb(0x64);
    outportb(0x64, 0xFE);
    for(;;);
}

[srg_13]

Thanks, but I already have a reboot. I was kinda hoping that it would be that simple to shut down the computer

-Stephen