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SECTION 3—FUNCTIONAL DESCRIPTION
This section describes how the digital switch and the software of System 25 provide control
and switching.
Digital Switch
Figure 3-1 shows a sehematic diagram of the System 25 digital switch.
The basic switch hardware consists of the following:
Common Control
Memory Bus
Call Processor Circuit Pack (CP)
Memory CP.
Switching Network
Time Division Multiplex (TDM) Bus
Port Circuits
System Resource Circuits: Service Circuit, Tone Detector, and Pooled Modem.
MEMORY BUS
COMMON
CONTROL
CALL
MEMORY
PROCESSOR
TDM BUS
SWITCHING
NETWORK
PORT
SERVICE
TONE
POOLED
CIRCUITS CIRCUIT
DETECTOR MODEM
SYSTEM RESOURCES
TRUNKS,
VOICE TERMINALS
Figure 3-1. System 25 Digital Switch
3-1