System Bus Design; 100/133 Mhz System Bus; Segment Descriptions And Lengths For Figure - Intel VC820 - Desktop Board Motherboard Design Manual

Layout/Routing Guidelines
2.9

System Bus Design

2.9.1

100/133 MHz System Bus

First, determine the approximate location of the processor and the chip set on the base board. An
example topology is shown in
100 MHz 2-way processor/Intel
electrically in the center of the bus. The SC242 connectors should be placed on either end of the
bus to allow the processors to terminate each end.
Table 2-12
topology shown in
components. For 2-way processor / Intel
in the unused slot when only one processor is populated. This is necessary to ensure signal integrity
requirements are met.
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Figure 2-36. Intel
Table 2-12. Segment Descriptions and Lengths for Figure 2-36
L1+L3 or L2+L3
Figure 2-37
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Figure 2-37. Intel
2-46
Figure
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820 chipset designs. The 82820 MCH should be placed
below provides segment descriptions and length recommendations for the investigated
Figure 2-36. Segment lengths are defined at the pins of the devices or
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Pentium III Processor Dual Processor Configuration
Processor
Segment
L1 SC242 connector to Centerpoint
L2 SC242 connector to Centerpoint
L3 Chip set breakout stub
SC242 distance from MCH
L1 + L2 SC242 spacing
shows the topology and trace lengths required for single processor designs.
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Pentium III Processor Uni-Processor Configuration
MCH
L(1): Z = 60Ω ± 15%
0
2-36. This example "star" topology is valid for 133 MHz and
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820 chipset designs, a termination card must be placed
Processor
L1 L2
L3
L(1,2,3): Z
MCH
Description
L1 Min = 1.75"
L1 Max = 4.5"
= 60Ω ± 15%
0
Min length Max length
(inches) (inches)
1.5 3.0
1.5 3.0
0.0 1.5
2.0 4.5
5.5
Processor
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Intel 820 Chipset Design Guide