CHAPTER 2 HARDWARE INSTALLATION
1. The 3 CPU clock frequencies that the system supports are 55MHz, 60MHz,
66MHz and 75MHz (To adjust SW1 pin 4, 5, and 6 ). See the following
chart to set the different Host Clock Frequencies.
4 5 6 Clock
ON ON OFF 55MHz
ON OFF OFF 60MHz
OFF OFF OFF 66MHz
OFF ON OFF 75MHz
SW1
CPU
2. The DIP Switch SW1 (1,2, and 3) is used to set the Core/Bus (Fraction)
ratio of the CPU. The actual core speed of the CPU is the Host Clock
Frequency multiplied by the Core/Bus ratio. For example:
If CPU Clock = 66MHz
Core/Bus ratio = 3/2
then CPU core speed = Host Clock x Core/Bus ratio
= 66MHz x 3/2
= 100MHz
3. The PCI Bus Clock is the CPU Clock Frequency divided by 2.
2.1-2 CPU Core Speed Derivation Procedure
1 2 3 Core/Bus Ratio
OFF OFF OFF 1.5 /3.5
ON OFF OFF 2
ON ON OFF 2.5/1.75
OFF ON OFF 3
SW1
CPU
2-2
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