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A case study: DX 200 Exchange (cont.)
nBCDU:Basic Data Communication
Unit: Serves various data services to OMU as access to X.25 and LANs
nM:
Marker Unit: Controls concentrators / space switches
nCM:
Central Memory: Contains user database, charging, signalling, routing
and exchange ensemble.
nSTU: Statistical Unit: Collects statistical
information on traffic and charging.
nCHU:Charging
Unit: Maintains charging database obtained from signalling
units.
nOMU:Operation
and Maintenance Unit: Allows personnel access to exchange memory, perform tests
an traffic measurements.