Compaq W4000 Manual De Usuario

Technical Reference Guide 

There are two "Time-out to Standby" timers used in APM: the System Timer and the IDE 
had Drive Timer. 
 
 

 
In POST, the ROM enables a timer in the ICH2 that generates an SMI once per minute. 
When the ROM gets the SMI it checks status bits in the ICH2 for activity at any of the 
following devices:  
 
♦  Keyboard  
♦  Mouse  
♦  Serial port(s)  
♦  Parallel port  
♦  IDE primary controller  
 

NOTE: The secondary controller is NOT included in order to support auto-
sense of a CD-ROM insertion (auto-run) in case Windows or NT is running. 
Note also that management of SCSI drives is the responsibility of the SCSI 
driver. Any IDE hard drive access resets the hard drive timer.  

 
If any of the activity status bits are set when the ROM gets the 1-minute SMI, it resets its 
time-out minute countdown according to the value (0 (default), 5, 10, 15, 20, 30, 40, 50, 
60, 120, 180, or 240 minutes) selected in the Setup utility (F10).  
 
 

 
During POST, an inactivity timer in the IDE hard drive controller is set to control hard 
drive spin down. This activity is independent of the system timer. The BIOS will not 
inform the O/S that it is time to go to sleep until there has been no IDE primary activity 
for the system time-out time. The IDE hard drive will spin down when its timer expires 
according to the countdown time (0 (disabled), 10, 15, 20, 30, 60, 120, 180, or 240 
minutes) selected in the Setup utility (F10).  

 

 

NOTE: The O/S (Win98 and later) can use the "Enable/Disable Timer Based Request" 
APM BIOS call to disable the system timer the BIOS uses so that the O/S can have direct 
control of the timing.  

 

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