Cpu Core Speed Derivation Procedure - MSI MS-5148 User Manual

2.1-2 CPU Core Speed Derivation Procedure

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.
ON
ON
OFF
OFF
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
Core/Bus ratio
then CPU core speed
OFF
ON
ON
OFF
3. The PCI Bus Clock is the CPU Clock Frequency divided by 2.
4 5
ON
OFF
OFF
ON
1 2
OFF
OFF
ON
ON
6 Clock
OFF 55MHz
OFF 60MHz
OFF 66MHz
OFF 75MHz
= 66MHz
= 3/2
= Host Clock x Core/Bus ratio
= 66MHz x 3/2
= 100MHz
3 Core/Bus Ratio
OFF 1.5 /3.5
OFF
OFF 2.5/1.75
OFF
2-2
2
3