Compaq 850 manual Waking Up in APM, USB Legacy Support

Technical Reference Guide

System OFF

There are two ways to turn the system off:

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™.

7.7.3.3Waking 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.

7.8USB 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.

Compaq Deskpro EXS and Workstation 300 Personal Computers 7-23

Featuring the Intel Pentium 4 Processor

First Edition - December 2000