Instruction manual

FUNCTIONAL DESCRIPTION
ON-BOARD
MICROPROCESSOR
TO
AUXILIARY
EQUIPMENT
Figure 3-9. Auxiliary Trunk (TN763) Unique Circuitry
Data Line (TN726)
The Data Line Circuit Pack (Figure 3-10) interfaces eight Asynchronous Data Units (ADUs)
data devices and the TDM bus. The ADUs are typically, in turn, connected to RS-232 type
devices. The Data Line has the following unique circuitry:
● Bit Clock
The bit clock circuitry is used to provide the Octal Asynchronous Terminal Mode Two
EIA Asynchronous LSIs (OATMEALs) with a clock frequency that is a multiple of each
baud rate. In addition, the clock rate is divided down to 160 kHz. The 160 kHz is
then compared to the 160 kHz system data clock and is phase-locked to it. The
phase-locked circuit is required for low speed operation.
● Bus Isolation
This portion of the circuit pack is used to isolate the microprocessor bus. Isolation is
required because the realized bus load exceeds the maximum limit specified for this
device, due to the large number of devices controlled by the NPE. The OATMEALs
are isolated from the common bus structure.
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