Compaq W4000 Manual De Usuario

Technical Reference Guide 

 

This system meets the hardware and firmware requirements for being ACPI compliant.  
This system supports the following ACPI functions: 
 
♦  PM timer 
♦  Power button 
♦  Power button override 
♦  RTC alarm 
♦  Sleep/Wake logic (S1,S3,  S4 (Windows 2000), S5) 
♦  C1 state (Halt) 
♦  PCI Power Management Event (PME) 
 

 
 
 

7.7.3  APM 1.2 SUPPORT 

Advanced Power Management (APM) is an extension of power management. In APM, the O/S 
decides when a transition to another power state should occur. If going to Standby or Suspend, it 
notifies all APM-aware drivers requesting approval for the state change. If all drivers approve (the 
BIOS is not involved in this process) each is instructed to go to that state, then the BIOS is told to 
go to that state. All versions of Windows, later versions of OS/2 and Linux support APM. . The 
BIOS ROM for these systems support APM 1.2 

The APM functions are initialized when the O/S loads. An INT 15h call is made to see if APM is 
supported by the BIOS, and at what level (1.0, 1.1 or 1.2). After that, the O/S gets a 32-bit address 
from the BIOS ROM so it can subsequently make 32 bit protected mode calls to access the 
different APM functions in the ROM.  

Table 8-6 lists all the APM calls that the O/S can make to the BIOS. These functions are the major 
difference between PM and APM.  
 

 

7-19