NEC Xen Master System Hardware Manual page 145

System Hardware Manual
Table 5-5 LED Indications (Continued)
LED No. Colour
LED 8 Red
LED 9 Red
LED 10 Red
LED 11 Red
4.2.5 Connectors
CN1
CN2
CN3
CN4
CN5
4.3 COI(8)-U( ) ETU
4.3.1 Description
The COI(8)-U13 (U19 for New Zealand) ETU provides an
interface with the Central Office. The COI ETU contains
circuitry for outside ring detection, holding, dialling and
control functions.
It also incorporates line reversal detection and busy tone
detection circuitry.
PCB
Marking
Cyclic Redundant Check (CRC)
CRC error in frame from network OR
channel busy
Ch 0 Channel 0 busy indication
Ch 1 Channel 1 busy indication
Ch 0 Channel 2 busy indication
Connects to backboard
Debug Port
Log Port
Expansion Header
Expansion Header
May 2001
Description
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