Technical Reference Guide
Compaq Deskpro Personal Computers
Third Edition - April 2001
8-23
System OFF
Therearetwowaystoturnthesystemoff:
1. Press and hold the power button for longer than 4 seconds (not recommended unless
absolutely necessary).
2. Software shut-down as directed by the O/S. This, being the normal procedure, allows
a NIC driver to re-arm the NIC for a Magic Packet™.
8.7.3.3 Waking Up in APM
Any of the following activities will cause the system to wake up:
♦ Keyboard
♦ Mouse
♦ Ring Indicate
♦ RTC alarm
♦ Magic Packet
The hard drive will not spin up until it is accessed. Any hard drive access will cause it to
wake up and resume spinning. Since the BIOS returns to the currently running software,
it is possible for the drive to spin up while the system is in Standby with the screen
blanked.
8.8 USB LEGACY SUPPORT
The BIOS ROM checks the USB port, during POST, for the presence of a USB keyboard. This
allows a system with only a USB keyboard to be used during ROM-based setup and also on a
system with an OS that does not include a USB driver.
On such a system a keystroke will generate an SMI and the SMI handler will retrieve the data
from the device and convert it to PS/2 data. The data will be passed to the keyboard controller and
processed as in the PS/2 interface. Changing the delay and/or typematic rate of a USB keyboard
though BIOS function INT 16 is not supported.
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