Nortel Networks Circuit Card 311 - Manual (Page 996)

996 NTBK51 Downloadable D-channel Handler daughterboard
The serial controller is the Zilog Z16C35 and is referenced as the Integrated
Controller (ISCC). The ISCC includes a flexible Bus Interface Unit (BIU)
and four Direct Memory Access (DMA) channels, one for each receive and
transmit. The DMA core of the ISCC controls the data transfer between
local RAM and the communication ports.
Sanity timer
A sanity timer is incorporated on the DDCH to prevent the MPU from getting
tied-up as the result of a hardware or software fault. If the MPU encounters
a hardware or software fault and enters a continuous loop, the sanity timer
enables the DDCH to reset itself.
A sanity timer is incorporated on the DDCH to prevent the MPU from getting
tied-up as the result of a hardware or software fault. The sanity timer permits
the DDCH to reset itself should it enter into an infinite loop.
If the MPU encounters a hardware or software fault and enters a continuous
loop, the sanity timer enables the DDCH to reset itself.
Bus timer
The bus timer presents an error signal to the MPU if an attempt to access a
device did not receive acknowledgment within the bus time-out period of
120 ms.
The bus timer presents an error signal to the MPU if an attempt to access
a device did not receive acknowledgment within the bus time-out period
of 120 microseconds.
The bus timer presents an error signal to the MPU if an attempt to access a
device did not receive acknowledgment within the bus time-out period of
120 ms.
Download operation
Downloading is performed in either of two modes: background mode or
maintenance mode. Before a download takes place, a D-channel link must
be configured. The following situations lead to software downloading:
• during initialization when new software is installed
• when enabling the card or application
• during card reset (due to loss of software or corruption)
• during a background audit
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 01.04 Standard
Release 5.0 23 May 2008
Copyright © 2003-2008, Nortel Networks
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