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Chapter 4 System Support
Compaq Deskpro EN Series of Personal Computers
Desktop and Minitower Form Factors
Third Edition - September 1998
4-28
4.5 SYSTEM CLOCK DISTRIBUTION
The system uses a Cypress CY2280 or compatible part for generation of most clock signals.
Table 4-17 lists the system board clock signals and how they are distributed.
Table 4–17.
Clock Generation and Distribution
Table 4-17.
Clock Generation and Distribution
Frequncy/Signal Source Destination
66, 100 MHz
(CPUCLK) [1]
CY2280 Processor, 82443 N. Bridge
66 MHz North Bridge AGP Slot
48 MHz “ 82371 S. Bridge, 87307 I/O Cntlr.
33 MHz (PCICLK) “ PCI Slots, 82371 S. Bridge
14.31818 MHz Crystal W48C67
14.31818 MHz CY2280 South Bridge, ISA slots
8.33 MHz (BCLK) South Bridge ISA slots
32.77 KHz Crystal South Bridge
NOTE:
[1] Depending on processor speed (refer to
Chapter 3, “Processor/Memory Subsystem”).