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CIRCUIT DESCRIPTION
49018-0697 <90-00089>
T
he functional schematic for the 49018 Station Selector
Subassembly is shown in Fig. 1. The circuit consists of:
♦
6 miniature 10-digit code select switches
♦
Two output station drivers
♦
An address buffer latch
♦
Two address comparators
♦
A digit counter
♦
A clock pulse delay circuit
♦
Two station address latches
♦
An interdigit and reset timer
♦
A supervisory decoder
♦
A busy latch
♦
A busy reset pulse circuit
♦
“0” and “1” digit output drivers
In Dantel’s 440 CMS and TMS single station package, the 49018
subassembly BCD address decoder is controlled by BCD inputs
from the 44020 DTMF Decoder Module. The 49018 provides
buffered outputs for two station addresses. It also includes
buffered outputs for busy control, clear, and “0” and “1” digits.
The outputs are applied to the 44022 Station Interface Module
or the 44023 PABX/Trunk Interface Module of the 440 CMS or
TMS.
Miniature 10-digit switches on the 49018 subassembly are used
to preset the two address codes (station 1 and station 2). These
codes can be one, two, or three digits each. When the correct
incoming BCD address is decoded, the respective station driver
is grounded. At the same time, the 49018 provides a ground
enable output for the ring generator start.
Decoding
The BCD digit inputs from the 44020 DTMF Decoder are loaded
into the address buffer latch using pins P1-1, -2, -3, and -4. The
digits are loaded on the positive edge of the strobe pulse input at
P1-5. The address buffer latch remains in a set state and its
output is applied to both station address comparators.
Refer to Fig. 2 for 49018 Subassembly-to-Host Module pin
connections.
P
3
AGE
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