| 摘要 |
Each telephone line of a telephone network is individually monitored to determine its on/off hook status and any control pulses or tones being impressed thereon. Each monitor unit when it has information to present generates a first interrupt signal which is fed to a block control unit. The block control unit in turn generates a second interrupt which is fed to a master control unit along with a binary value indicative of the interrupting monitor unit. When the master control recognizes a second interrupt, a CPU interrupt along with a second binary value indicative of the block unit generating the second interrupt is generated. The second binary value (1) provides a block select address signal that enables the interrupting block unit to present to a central processing unit (CPU) data indicative of the interrupting monitor and (2) provides to the CPU data indicative of the block unit to which the interrupting monitor belongs. Upon receipt of a CPU interrupt, the CPU reads at a specific memory address the binary data that is indicative of the interrupting monitor and then issues a read command to the interrupting monitor which presents its data to the CPU for processing in accordance with the CPU program.
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