Microprocessor - Avaya Nortel Communication Server 1000 Reference

Microprocessor

The NTRB21 is equipped with bit-slice microprocessors that handle the following major tasks:
• Task handler: also referred to as an executive. The task handler provides orderly per-
channel task execution to maintain real-time task ordering constraints.
• Transmit voice: inserts digital pads, manipulates transmit AB bits for DS1, and provides
graceful entry into T-Link data mode when the data module connected to the DTI/PRI
trunk is answering the call.
• Receive voice: inserts digital pads and provides graceful entry into T-Link data mode when
the data module connected to the DTI/PRI trunk is originating the call.
• T-Link data: a set of transmit and receive vectored subroutines which provides T-Link
protocol conversion to and from the DM-DM protocol.
• Receive ABCD filtering: filters and debounces the receive ABCD bits and provides change
of state information to the system.
• Diagnostics
• Self-test
Digital pad
The digital pad is an EPROM whose address-input to data-output transfer function meets the
characteristics of a digital attenuator. The digital pad accommodates both µ255-Law and A-
Law coding. There are 32 combinations each for µ255 to µ255, µ255 to A-Law, A-Law to µ255,
and A-Law to A-Law. These values are selected to meet the EIA loss and level plan.
Table 266: Digital pad values and offset allocations
Circuit Card Reference
Offset
0
1
2
3
4
5
6
7
8
PAD set 0
0dB
2dB
3dB
4dB
5dB
6.1dB
8dB
–1dB
–3dB
Architecture
PAD set 1
–7db
–8db
–9db
–10db
0.6db
7db
9db
10db
11db
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