8. Serial Controller
84
Modem Status Register
Register: Modem Status
Address: 3FEh
Access: Read
DCD
RIN
DSR
CTS DDD
RIT
DDR DCS
7
6
5
4
3
2
1
0
Delta Clear To Send
0 No transition
1 Transition
Ring Indicator Trailing Edge
0 No trailing edge
1 Trailing edge
Delta Data Carrier Detect
0 No transition
1 Transition
Clear To Send
0 Negative voltage
1 Positive voltage
Data Set Ready
0 Negative voltage
1 Positive voltage
Ring Indicator
0 Negative voltage
1 Positive voltage
Data Carrier Detect
0 Negative voltage
1 Positive voltage
Delta Data Set Ready
0 No transition
1 Transition
Modem Status Register
ADDITIONAL INFORMATION
Refer to the Intel 386 EX data book for more information on the COM1 and COM2 serial
controller operating modes. A product overview of the Intel 386 EX is available on Intel's
web site at
http://developer.intel.com/design/intarch/prodbref/27270903.htm
.
Refer to the National Semiconductor PC87303 data book for more information on the
COM3 and COM4 serial controller operating modes. National's web site is located at
http://www.national.com
.