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.