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Technical Reference Guide
Compaq Deskpro EXS and Workstation 300 Personal Computers
Featuring the Intel Pentium 4 Processor
First Edition - December 2000
4-39
4.8.3.2 LPC47B357 I/O Controller Miscellaneous Functions
The desktop and minitower systems utilize the following specialized functions built into the LPC
47B357 I/O Controller:
♦ Power/Hard drive LED control – The I/O controller provides color and blink control for the
front panel LEDs used for indicating system events as listed below:
System Status Power LED HD LED
S0: System on (normal operation) Steady green Green w/HD activity
S1: Suspend Blinks green @ 1 Hz Off
S3: Suspend to RAM Blinks green @ 1 Hz Off
S4: Suspend to disk Blinks green @ 0.5 Hz Off
S5: Soft off Off - clear Off
Backplane board not seated Steady red Steady red
Processor not seated Steady red Off
CPU thermal shutdown Blinks red @ 4 Hz Off
ROM error Blinks red @ 1 Hz Off
Power supply crowbar activated Blinks red @ 0.5 Hz Off
System off Off Off
♦ I/O security – The parallel, serial, and diskette interfaces may be disabled individually by
software and the LPC47B357’s disabling register locked. If the disabling register is locked, a
system reset through a cold boot is required to gain access to the disabling (Device Disable)
register.
♦ Processor present/speed detection – One of the battery-back general-purpose inputs (GPI26)
of the LPC47B357 detects if the processor has been removed. The occurrence of this event is
passed to the ICH that will, during the next boot sequence, initiate the speed selection routine
for the processor. The speed selection function replaces the manual DIP switch configuration
procedure required on previous systems.
♦ Legacy/ACPI power button mode control – The LPC47B357 receives the pulse signal from
the system’s power button and produces the PS On signal according to the mode (legacy or
ACPI) selected. Refer to chapter 7 for more information regarding power management.