Memory; Serial Interface - Avaya Nortel Communication Server 1000 Reference

Memory

The MSDL card contains two megabytes of Random Access Memory (RAM) for storing
downloaded peripheral software that controls MSDL port operations. The MSDL card includes
the shared RAM that is used as a communication interface buffer between the CPU and the
MPU.
The MSDL Flash Erasable Programmable Read Only Memory (Flash EPROM) also includes
the peripheral software to protect it against a power failure or reset. MSDL can copy peripheral
software directly from the Flash EPROM after power up or reset instead of requesting that the
system CPU download it.
The MSDL card also contains Programmable Read Only Memory (PROM) for firmware that
includes the bootstrap code.

Serial interface

The MSDL card provides one monitor port and four programmable serial ports that can be
configured for the following various interfaces and combinations of interfaces:
• synchronous ports 0–3
• asynchronous port 0
• DCE or DTE equipment emulation mode
• RS-232 or RS-422 interface
Transmission mode – All four ports of the MSDL can be configured for synchronous data
transmission by software. Port 0 can be configured for asynchronous data transmission for
CRT, TTY, and printer applications only.
Equipment emulation mode – Configure an MSDL port to emulate DCE or DTE by setting
switches on the card and downloading LD 17 interface parameters.
I/O port electrical interface – Each MSDL port can be configured as an RS-232 or RS-422
interface by setting the switches on the MSDL card. MSDL ports use Small Computer Systems
Interface (SCSI) II 26-pin female connectors.
Figure 90: MSDL functional block diagram
the MSDL as an operational platform. It illustrates operation routing from the CPU, through the
MSDL, to the I/O equipment. It also shows an example in which DCH operation peripheral
software in the MSDL controls functions on ports 2 and 3.
Circuit Card Reference
on page 323 shows the system architecture using
Functional description
July 2011 321