NEC Univerge SV8500 Operation And Maintenance Manual page 52

• C-Level Infinite Loop
A program repeatedly executes specific routines due to a fault of the main memory, data destruction,
etc. The program is not able to process normally. This faulty condition is referred to as Program Infinite
Loop. C-Level infinite loop is a state where a specific program is endlessly repeated, blocking period-
ical programs to be executed.
• B-Level Infinite Loop
This is a state where a program infinite loop has occurred during connection processing and the
connection for the next call is not able to process.
• Port Microprocessor (PM)
Each line/trunk card mounted in the PIR is equipped with a processor called Port Microprocessor (PM),
which continuously supervises the lines/trunks.
• Ready Error
For acknowledging the connection between the CPU and a circuit card, an interface signal called Ready
Signal is used. When the CPU has accessed a specific circuit card and the normality of the connection
is acknowledged, the Ready Signal is returned to the CPU within a certain time period. If the Ready
Signal is not returned to the CPU within the above time period after access, the situation is referred to
as Ready Error.
• Parity Error
For confirming the normality of data transfer between the CPU and the circuit card under the control
of the CPU, a parity check is made. When an error is detected in a parity check, it is referred to as Parity
Error. Parity check means to confirm the normality of data by adding an error detecting parity bit to a
set of data to transfer.
When a set of data is transferred, a parity bit is added to the data so that the data has an even-number
of "1" bits (referred to as Even Parity). When there is an odd-number of "1" bits in the received one set
of data, it is detected as an error.
• Monitor Restart (Phase 0)
Monitor Restart processing suspends current processing in progress without applying any hardware
controlling, allowing the system to restart its operations from the Monitor Program. The system aban-
dons only the processing of the calls being handled by the program, and maintains all the connections
that have already been established. In the case of CPU system fault such as out-of-memory fault, the
system executes the monitor restart after outputting the system message and setting the hidden memory
fault.
• Phase 1 Restart
The system is initialized. All connections except for two-way connections that have already been
established are forcibly released.
• PM (Line/Trunk Card) Make-Busy Restart
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CHAPTER 1 General