Microprocessors - Avaya Nortel Communication Server 1000 Reference

Microprocessors

One microprocessor does the following:
• handles data transfer between each pair of serial ports and software
• reports the status of each port
• takes commands from software to control the activities of the ports
The microprocessors also handle some D-channel data processing in DCHI mode.
DMA controller
A Z80A-DMA chip controls the data transfer between local RAM memory and communication
ports. The DMA channels are only used in the receive direction (from line to SSC), not in the
transmit direction.
Random Access Memory (RAM)
A total of 32 KBytes of RAM space for each pair of ports is used as the communication buffer
and for firmware data storage.
Read Only Memory (ROM)
A total of 32K bytes of ROM space for each pair of ports is reserved as a code section of the
DCH-PORT firmware.
LAPD data link/asynchronous controller
One chip controls each pair of independent communication ports. It performs the functions of
serial-to-parallel and parallel-to-serial conversions, error detection, and frame recognition (in
HDLC). The parameters of these functions are supplied by the DCH-PORT firmware.
Counter/timer controller
Two chips are used as real-time timers and baud-rate generators for each pair of
communication ports.
Circuit Card Reference
Functional description
July 2011 545