User manual

8. Serial Controller

Modem Status Register

Address: 3FEh

Access: Read

DCD

RIN

DSR

CTS DDD RIT

DDR

DCS

76 5 432 10

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.