Nortel Networks Circuit Card - Manual (Page 787)

NTBK51 Downloadable D-channel Handler daughterboard Page 787 of 906
Circuit Card Description and Installation
Functional description
The main functional blocks of the NTBK51 architecture include the
following:
• Microprocessors
• Main memory
• Shared memory
• EPROM memory
• Flash EPROM memory
• EEPROM memory
• Serial communication controller
• Sanity timer
• Bus timer
Microprocessors
One microprocessor handles data transfer between each serial interface and
software, reports the status of each port and takes commands from the
software to control the activities of the ports. A high performance MPU
supports the D-channel from the PRI card and other software applications
running simultaneously on other ports of the DDCH card.
The microprocessor performs the following functions:
• sanity check and self tests
• message handling between the CS 1000S, CS 1000M Cabinet, and
Meridian 1 PBX 11C Cabinet and the card
• four port serial communication controller handling with Direct Memory
Access (DMA)
• program download from the Small System Controller