how to turn off a PC?

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zhak

Joined: 12 Apr 2005
Posts: 501
Location: Belarus

zhak 11 Aug 2005, 21:13

There are many different ways to reboot a PC, but how to turn off the power?

11 Aug 2005, 21:13

gunblade

Joined: 19 Feb 2004
Posts: 209

gunblade 11 Aug 2005, 23:45

If your bios has APM support, the following should do it.

Code:

mov ax, 0x5307
mov bx, 1
mov cx, 3
int 0x15

taken from the linux kernel apm.c, although the apm docs says that action 3 (off) cant be used with device 1 (ALL). might as well try and see Wink

Edit: And if that doesnt work, try it out with

Code:

mov bx, 0

rather than

Code:

mov bx, 1

if that still doesnt work, its likely your bios doesnt have APM support

11 Aug 2005, 23:45

Night Rider

Joined: 28 Jul 2005
Posts: 72

Night Rider 11 Aug 2005, 23:56

http://www.acpi.info/

11 Aug 2005, 23:56

Night Rider

Joined: 28 Jul 2005
Posts: 72

Night Rider 11 Aug 2005, 23:58

This is method using BIOS, but there are ways of direct hardware ACPI uni-unterface.

11 Aug 2005, 23:58

Night Rider

Joined: 28 Jul 2005
Posts: 72

Night Rider 12 Aug 2005, 00:01

Ways of using

12 Aug 2005, 00:01

THEWizardGenius

Joined: 14 Jan 2005
Posts: 382
Location: California, USA

THEWizardGenius 12 Aug 2005, 01:38

How do you program ACPI? The APM examples can be derived from the APM spec documentation (which describes all the BIOS calls) but ACPI specs do not describe BIOS calls, hardware support, or anything. Does anyone know how to "tell" ACPI to shutdown? No websites or documents that I've seen do.

Note: I wouldn't use the APM code if I were you. On my computer, for example, the BIOS merely prints gibberish on the screen and crashes. Not all systems support it, or support it properly/well, so it's unsafe to use it. There's a BIOS call for detecting APM, but even that crashes my PC. On older laptops, however, it works virtually every time (including my 486 Wink

)

If I remember right, MenuetOS used to have APM code but they removed it due to compatibility issues.

It's kinder to print a "It is now safe to turn your computer off" message and halt, ala Windows 95, rather than expect the user to put up with nonsense all over the screen and no more response from the OS!

12 Aug 2005, 01:38

smiddy

Joined: 31 Oct 2004
Posts: 557

smiddy 12 Aug 2005, 04:48

zhak wrote:

There are many different ways to reboot a PC, but how to turn off the power?

Sorry, but I have to:

The On/Off button on the front of the computer, push it! Razz

Seriously, there are many ways of turning of the computer, but usually they are not the same for all computers. ACPI is one ay, another are the BIOS calls. Try looking at MenuetOS to see that code. There is a snippet at the end of a routine (the name escapes me now) with several BIOS calls that need to be done in order for it to work; but it doesn' t work on all machines.

12 Aug 2005, 04:48

Chewy509

Joined: 19 Jun 2003
Posts: 297
Location: Bris-vegas, Australia

Chewy509 12 Aug 2005, 06:11

THEWizardGenius wrote:

How do you program ACPI?

ACPI is accessed via an entry listed in the ACPI Tables (see int 15h, e820h). You normally read the ACPI Config table, find the system information table, and from there modify the system state table. To power off the system just set the system power state (S0) to D3 (power-off).

see: www.acpi.info -> ACPI v3.0, Section 5.

12 Aug 2005, 06:11

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