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FUNCTIONAL DESCRIPTION
G. MODEM STATUS REGISTER
+------+
D7 | DCD |----- Data carrier detect
+------+
D6 | RI |----- Ring indicator
+------+
D5 | DSR |----- Data set ready
+------+
D4 | CTS |----- Clear to send
+------+
D3 | DDCD |----- Delta data carrier detect
+------+
D2 | TERI |----- Trailing edge ring indicator
+------+
D1 | DDSR |----- Delta data set ready
+------+
D0 | DCTS |----- Delta clear to send
+------+
Figure 13. MODEM status register bit definitions.
DCD - Data Carrier Detect:
Complement of the DCD input.
RI - Ring Indicator:
Complement of the RI input.
DSR - Data Set Ready:
Complement of the DSR input.
CTS - Clear To Send:
Complement of the CTS input.
Bits DDCD, TERI, DDSR, and DCTS are the sources of
MODEM status interrupts. These bits are reset when
the MODEM status register is read.
DDCD - Delta Data Carrier Detect:
Indicates the Data Carrier Detect input has
changed state.
TERI - Trailing Edge Ring Indicator:
Indicates the Ring Indicator input has changed
from a low to a high state.
DDSR - Delta Data Set Ready:
Indicates the Data Set Ready input has changed
state.
DCTS - Delta Clear To Send:
Indicates the Clear to Send input has changed
state.
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