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MS-5119 version 1.1
1. System Board Layout:
1. Clock Selection: JK, JC2, JC1, JSCLK
Set Jumper JK, JC2, JC1 , and JSCLK according to the Pentium 75Mhz,
90MHz, 100MHz, 120MHz, or 133MHz. See Figure 1-1 for the jumper
location.
JK, JC2, JC1, JSCLK Settings
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CPU Speed
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JK (Note 1)
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JC2 (Note 2)
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JC1 (Note 1)
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JSCLK
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1
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2
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3
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4
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3
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2
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1
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75MHz
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Short
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Short
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Short
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Short
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Open
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Open
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Open
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Short
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Short
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90MHz
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Short
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Open
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Short
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Open
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Open
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Open
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Short
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Short
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Open
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100MHz
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Open
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Short
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Open
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Short
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Open
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Open
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Short
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Short
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Open
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120MHz
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Short
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Open
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Short
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Open
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Open
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Short
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Short
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Short
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Open
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133MHz
|
Open
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Short
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Open
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Short
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Open
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Short
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Short
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Short
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Open
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Note 1: The 3 Host clock frequencies that the system supports are
50Mhz, 60Mhz, and 66.6Mhz. See the following chart to set the jumper
JK for the different Host Clock frequencies.
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JK
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Host Clock Frequency
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1
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2
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3
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4
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Short
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Short
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Short
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Short
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50MHz
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Short
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Open
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Short
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Open
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60MHz
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Open
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Short
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Open
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Short
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66.6MHz
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Note 2: The jumper JC2 and JC1 set the Bus/Core (Fraction) ration
of the CPU. See Below
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JC2
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JC1
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Bus/Core Ratio
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Previous P54C/CQs/CS
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New P54CS Por (C-Step)
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Open
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Open
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2 / 3
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2 / 3
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Open
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Short
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1 / 2
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1 / 2
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Short
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Open
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1 / 3
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1 / 3
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Short
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Short
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1 / 4
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2 / 5
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The actual core speed of CPU is the Host Clock frequency multiply
by Core/Bus ratio. For example, if the Host Clock frequency is 66.6MHz,
and the Core/Bus ratio is 3/2, the acutal CPU core speed will be 66.6
x 3/2 = 100MHz.
The System has reserved space for future usage of 150/60MHz and 180/60MHz
CPU. The Host Clock frequency is 60MHz and Bus/core ratio is 2/5 for
the 150/60MHz CPU, and, the HOst Clock frequency is 60MHz and Bus/core
ratio is 1/3 for the 180/60 MHz CPU.
Note 3: The PCI bus clock is the host clock frequency divided by 2
and the ISA bus clock is the PCI bus clock divided by 3 or 4. We recommend
that the ISA bus clock is the PCI bus clock divided by 3 when the
host clock frequency is 50MHz and divided by 4 when the Host Clock
frequency is 60MHz or 66.6 MHz. The jumper JSCLK is to set the PCI
Bus Clock either divided by 3 or 4 for the ISA Bus clock.
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3
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2
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1
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Open
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Short
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Short
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ISA Bus Clock = PCI Bus Clock divided by
3
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Short
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Short
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OPen
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ISA Bus Clock = PCI Bus Clock divided by
4
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BACK TO TOP
CPU Voltage Selector: JVCC3
Jumper JVCC3 selects a 3.4V/3.5V voltage power source for P54C. See
figure 1-1 for the location of the jumper.
JVCC3 Setting
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CPU Voltage
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JVCC3
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3.4V
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Short
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3.5V
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Open
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