Device Input/Output Layer; Utilities Layer; Main Control Processor Applications Software; Peripheral Control Processor Software - Mitel SX-200 Practices

General Description
download software from the Main Controller memory to the Peripheral Controllers'
memory using one or two channels per peripheral bay. During system operation, a
single channel is used as a communication link between the Main and Peripheral
Processors. Messages are sent in HDLC formatted frames, ensuring error-free
transmission of data.
Device Input/Output layer
5.6 This layer handles low level details of interfacing to input/output devices such as
telephony devices and N-232 ports.
Utilities layer
5.7 This software layer provides general utilities needed for resource management, error
handling, and command interpretation.
Main Control Processor Applications Software
5.8
The Main Control Processor Applications software is responsible for controlling all
activities in the SX-200 DIGITAL PABX. It communicates with the peripheral
processors via the Communications software layer for such things as "origination",
"digits received", etc. It also interprets Classes of Service, System Abbreviated Dial,
Personal Speed Call, Automatic Route Selection, etc. The Main Control Processor
software controls all Call Processing, Customer Data Entry, and Maintenance
management applications.
Peripheral Control Processor Sottware
5.9 The peripheral processor handles tasks that are real-time intensive, such as
debouncing switchhooks, collecting rotary dial pulses, tone cadencing, and signaling
on trunks. The peripheral processor is also responsible for monitoring hardware
activity, such as cards being added and removed, and reporting all events to the
Main Control Processor via the Message Subsystem.The Main Control Processor
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acts as the manager of the tasks performed by the Peripheral Control Processor.
Database
5.10 The Call Processing software is stored on floppy disk. Upon system power-up, the
disk data is transferred to the Main Control Dynamic Random Access Memory.
Customer Data Entry information is kept on floppy disk for retrieval in case of major
system failures. Other system information such as switchhook flash timing, trunk
timings, and rotary digit translation for different countries, is routed to the Peripheral
Control systems for processing.
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