System Considerations - Avaya Nortel Communication Server 1000 Reference

card includes baud rate generators, RS-232-C driver/receiver pairs, and the switches and logic
needed to configure each UART.
Figure 152: NT8D41BA QSDI paddle board block diagram

System considerations

In dual-processor Meridian 1 systems, the QSDI paddle board behaves differently depending
on which backplane socket it is installed. Installing the paddle board into a socket in the network
area of the backplane allows it to work when either of the system processors is active. Installing
the paddle board into a socket in the CPU area of the backplane allows it to work only when
that CPU is active.
The QSDI paddle board is normally installed into a socket in the network area of the backplane.
This allows it to be accessed by either of the system processors. This is necessary because
the active CPU switches automatically each night at midnight and whenever a fault occurs on
the active CPU card.
The QSDI paddle board can also be installed into a socket in the CPU area of the backplane
(supported in NT6D39AA shelves only). This is done when performing maintenance or an
upgrade on the Meridian 1 system.
The QSDI paddle board is plugged into the CPU that is not the active system CPU. One of the
serial ports on the QSDI paddle board is then connected to a maintenance terminal and the
CPU board is put into maintenance mode. Diagnostics can then be run from the maintenance
Circuit Card Reference
Functional description
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