Sun Microsystems SPARCserver 1000 System Installation Manual page 59

Key Switch
LED Indicators
Module
MQH (Memory Queue Handler)
The key switch on the system front panel has four positions: Standby, On,
Diagnostics, and Locked (reset switch is disabled, L1-A is disabled).
System Front Panel
For an explanation of this display, refer to Table 3-1, "Front Panel LED System
Status."
System Board
The system board has ten LEDs on the board rear panel. Two green LEDs (left
positions) denote the presence of zero, one or two SuperSPARC modules. The
remaining eight yellow LEDs (right positions) display board activity and
status.
See SuperSPARC Module.
The MQH on the system board provides the interface between the system
board SIMMs and the backplane XDBus. There is one MQH on a system board.
Glossary-5