Compaq W4000 manual Going to Sleep in APM, System/Hard Drive Standby, System Suspend

Chapter 7 BIOS ROM

7.7.3.2 Going to Sleep in APM

There are three levels of system sleep in APM: System/Hard Drive Standby, System Suspend, and System Off.

System/Hard Drive Standby

System Standby is achieved only by a system timer time-out, at such time the following occurs:

1.All APM-aware device drivers put their respective devices into “Device Standby.”

2.The O/S makes a BIOS call to go into System Standby.

NOTE: The BIOS ROM of these systems will not turn the fan(s) off as on previous systems).

If the hard drive timer times out due to inactivity the hard drive motor stops spinning the platters. Depending on drive type, some drives can cut power to some of the drive electronics that are not needed during standby. The drive(s) can be in this state with the system still awake. Since the hard drive timer is in the hard drive controller and triggered by drive access, the system can be in Standby with the hard drive(s) still spinning (awake).

System Suspend

System Suspend is invoked by pressing and releasing the power switch in under four seconds (pressing and holding the switch longer that four seconds will turn the system off).. The system does not time-out from Standby into Suspend.

Upon invoking Suspend, the following actions occur:

1.All APM-aware device drivers put their associated devices into “Device Standby.”

2.The O/S makes a BIOS call to go into Standby, and the BIOS:

a.Spins down the IDE drives

b.Halts the processor. The processor remains halted until the next 55ms tick from the RTC.

c.At the 55ms tick of the RTC the processor executes a BIOS routine to check to see if anything has happened to wake the system up. If not, the processor is halted again.

d.Steps B and C are repeated until a wake-up event occurs.

NOTE: These systems will not turn the fan(s) off as in previous systems.

7-22Compaq Evo and Workstation Personal Computers

Featuring the Intel Pentium 4 Processor

Second Edition - January 2003