Sun Microsystems 5500, Reference Manual

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B-18 Sun Enterprise 6500/5500/4500 Systems Reference Manual • April 1998
B.10 Clock+ Board
The clock+ board is located at the rear of the system, directly below the peripheral
power supply. When replacing the clock+ board, orient the board with the
component side up (
FIGURE B-12
).
The clock+ board provides 16 pairs of system clocks, 32 pairs of processor clocks.
All processors run at the same clock speed. The system clock and the processor
clocks are derived from a single clock source. The frequency of the clock source as
well as the processor and system clocks are programmable and set by firmware. The
processor clock frequency is set to match the lowest-frequency processor in the
system.
The clock+ board also includes central devices including serial ports, keyboard and
mouse, and a time-of-day (TOD) chip.
FIGURE B-12
Clock+ Board