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Circuit Pack Descriptions
Issue 3 June 2000
7-5
General Description of Operation
7
The SYSCTL circuit pack provides the majority of the control functions on the
shelf. These include circuit pack monitoring, performance monitoring, protection
switching, and user interfaces.
The SYSCTL, which contains a microprocessor, controls links to all other circuit
packs in the system and links to user interfaces. The processor also provides link
access procedure (LAPD) and link access procedure packet data processing to
support SONET section DCC.
Detailed Description of Operation
7
Control Circuitry
7
Processor.
7
Figure 7-2 provides an overall block diagram of the SYSCTL circuit
pack. This processor is the highest level processor in the system.
Memory
7
Program Flash-EPROM.
7
The main program is stored in the flash-EPROM, which
combines the nonvolatility of EPROM with the in-circuit reprogramming ability of
electrically erasable programmable read-only memory (EEPROM). Electrically
erasable programmable read-only memory (FEEPROM) allows in-service
software upgrades to be performed locally or remotely without replacing the
SYSCTL circuit pack. Program upgrades of remote systems can also be done via
the DCC. Of course, software upgrades may also be accomplished by replacing
circuit packs with packs that have already had software upgrades.
RAM.
7
The main processor's random access memory (RAM) is used to store all
volatile information such as system alarms, performance-monitoring information,
and parameters for the main processor's operating system.
EEPROM.
7
All nonvolatile parameters such as provisioning are stored in the
EEPROM, which maintains its data indefinitely during a power loss.
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