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NDA-24300 CHAPTER 2
Page 25
Issue 1
SYSTEM MAINTENANCE OUTLINE
2.7 Explanation of Terms
• C-Level Infinite Loop
The program repeatedly executes specific routines due to a fault of the main memory, data destruction,
etc. The program is not able to be processed normally. This faulty condition is referred to as Program
Infinite Loop. C-Level infinite loop is a state where a clock-level program, which runs under clock
interrupt disable state, is in an infinite loop status.
• B-Level Infinite Loop
This is a state where a program infinite loop has occurred during a connection processing and the
connection for the next call is not able to be processed.
• Port Microprocessor (PM)
Each line/trunk card mounted in the PIM 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 6 µs. If the Ready signal
is not returned to the CPU within 6 µs 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, 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 be transferred.
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 (it is 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
Monitor restart processing suspends current processings in progress without applying any hardware
controlling, allowing the system to restart its operations from the monitor program.
The system abandons only the processings of the calls being handled by the program, and maintains
all the connections that have already been established.
• Circuit Card Front Initializing Restart
The whole system is forcibly initialized. However, the initialization varies with the setting of the
SENSE switch on the DSP of CPU (see Table 2-2).