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2 System Board
Devices on the Processor-Local Bus
Bus Frequencies There is a 14.318 MHz crystal oscillator on the system board. This frequency
is multiplied to 66 MHz by a phase locked loop. This is further scaled by an
internal clock multiplier within the processor.
For example, the Pentium II 300 MHz processor multiplies the 66 MHz
system clock by 4.5. Switches 1 and 2, on the system board switches, set the
frequency of the Processor-Local bus, which for all HP Kayak XA PC
Workstation models, is 66 MHz. Switches 3, 4 and 5 set the clock multiplier
ratio.
The computer may execute erratically, if at all, or may overheat, if it is
configured to operate at a higher processor speed than the processor is
capable of supporting. This can cause damage to the computer.
Setting the switches to operate at a slower speed, than the processor is
capable of supporting, can still cause erratic behavior in some cases, and
would reduce the instruction throughput in others.
1.
Processor bus frequency is always set at 66MHz for all XA PC Workstations models.
2.
Switches are provided to match the system board to processor frequency when a
system board repair is performed.
Processor
Frequency
Switch
Processor
Local Bus
Frequency
1
PCI Bus
Frequency
ISA Bus
Frequency
Switch
2
Frequency
Ratio
Processor:
Local Bus
1 2 3 4 5
233 MHz
Open Open 66 MHz 33 MHz 8.25 MHz Open Closed Closed 3.5 : 1
266 MHz Open Open 66 MHz 33 MHz 8.25 MHz Closed Open Open 4 : 1
300 MHz
Open Open 66 MHz 33 MHz 8.25 MHz Closed Open Closed 4.5 : 1
333 MHz
Open Open 66 MHz 33 MHz 8.25 MHz Closed Closed Open 5 : 1