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10 P/E-P55T2P4D User’s Manual
III. INSTALLATION
6. CPU to BUS Frequency Ratio (JP15 & 16)
These jumpers set the frequency ratio between the Internal frequency of the
CPU and the External frequency (called the BUS Clock) within the CPU. These
must be set together with the above jumpers CPU External (BUS) Frequency
Selection.
7. CPU External (BUS) Frequency Selection (JP29 & 30)
These jumpers instructs the clock generator what frequency to send to the CPU.
These allow the selection of the CPU’s External frequency (or BUS Clock). The
BUS Clock times the BUS Ratio equals the CPU's Internal frequency (the ad-
vertised CPU speed).
50MHz
60MHz
66MHz
1
2
3
CPU External Clock (BUS) Frequency Selection (Rev 1.3)
CPU : BUS Frequency Ratio (1.5x, 2.0x, 2.5x, 3.0x)
1.5 x 2.0 x 2.5 x 3.0 x
JP30
JP29
JP16
JP15
JP16
JP15
JP16
JP15
JP16
JP15
1
2
3
JP30
JP29
1
2
3
JP30
JP29
Set the above jumpers by the Internal speed of the Intel CPU as follows:
(BUS Ratio) (BUS Frequency)
Internal Ratio External JP16 JP15 JP30 JP29
200MHz 3.0x 66MHz [open] [short] [1-2] [2-3]
180MHz 3.0x 60MHz [open] [short] [2-3] [1-2]
166MHz 2.5x 66MHz [short] [short] [1-2] [2-3]
150MHz 2.5x 60MHz [short] [short] [2-3] [1-2]
133MHz 2.0x 66MHz [short] [open] [1-2] [2-3]
120MHz 2.0x 60MHz [short] [open] [2-3] [1-2]
100MHz 1.5x 66MHz [open] [open] [1-2] [2-3]
90MHz 1.5x 60MHz [open] [open] [2-3] [1-2]
75MHz 1.5x 50MHz [open] [open] [2-3] [2-3]
(Jumpers)
III. INSTALLATION