Compaq AlphaPC 264DP Technical Reference Manual page 57

4.5 Clock Subsystem
The system clocks can be divided into five areas:
•
Input clocks required by the CPU/system
•
Clock forwarding to/from the system logic
•
Memory system
•
PCI system
•
Miscellaneous oscillators and clocks required for the peripheral interfaces and
functions
4.5.1 CPU and System Clock Generation
There is a crystal for 32.768 KHz, and other clocks are provided through a PC clock
generator chip. A 14.1818-KHz crystal is used as the input clock for the PC clock
generator.
A 32.768-KHz crystal provides input to the TOY function of the southbridge.
A 14.3-MHz oscillator (69.9-ns period) output is buffered from the PC clock genera-
tor to the host PCI-to-ISA bridge and the three ISA slots. This is the standard
14.31818-MHz ISA clock.
Figure 4–2 shows the clock distribution.
12 February 1999 – Subject To Change
Clock Subsystem
Functional Description
4–7