DEC Dual RS-232

pinout

Found on the DEC Multia and DEC UDB (Universal Desktop Box). It contains two Serial ports on one connector. The 1st port is located on the normal pins, and the 2nd port is located on some "spare" pins.

25 pin D-SUB male connector  at the computer

Pin Port Name Dir Description 1   n/c   Not connected 2 1 TXD Transmit Data 3 1 RXD Receive Data 4 1 RTS Ready To Send 5 1 CTS Clear To Send 6 1 DSR Data Set Ready 7 1+2 GND - Ground 8 1 DCD Data Carrier Detect 9   n/c   Not connected 10   n/c   Not connected 11 2 DTR Data Terminal Ready 12 2 DCD Data Carrier Detect 13 2 CTS Clear To Send 14 2 TXD Transmit Data 15   n/c   Not connected 16 2 RXD Receive Data 17   n/c   Not connected 18   n/c   Not connected 19 2 RTS Ready To Send 20 1 DTR Data Terminal Ready 21   n/c   Not connected 22 1 RI Ring Indicator 23 2 DSR Data Set Ready 24   n/c   Not connected 25 2 RI Ring Indicator Note: Direction is DTE (Computer) relative DCE (Modem).

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