Sun Microsystems SUN BLADE 150, Service Manual

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Appendix C Functional Description C-13
C.5.9 NVRAM/TOD
The system requires at least 8 Kbytes of nonvolatile static RAM to store the variables
for the operating system and a real time clock to do timekeeping. The device also
has both functions integrated plus the self-contained battery. It also has a
programmable alarm interrupt output that can be used by the software to enable
auto-shutdown (auto suspend/resume) as a power management choice.
C.6 Reset Types
The CPU has several types of resets. The resets affect different levels of the system
devices and the processor. As an example, a Power-on Reset (POR) resets all devices
on the motherboard as well as any PCI card that is plugged in. A soft reset is under
software control and is used to reset particular registers that reside in the devices on
the motherboard.
C.7 Clocking
C.7.1 Clock Generation
The four clock domains in the Sun Blade 150 system. The domains are the CPU,
SDRAM, PCI, and miscellaneous clocks.
All the clocks in those four domains are generated from clock synthesizers or
dedicated crystals on the motherboard except SDRAM clocks, which are generated
by the CPU.