HCT14 with DB 9 serial port

I have found a cable with one side DB 9 female socket with HCT14 ic in side it could any one suggest me for what purpose it is used

Electrical isolation of 1500 V or higher is possible with this cost-effective RS232 interface. It is ideal for various data-communication designs, including medical instrumentation and devices within harsh electrical environments. The interface uses the host's TXD (transmit data), RXD (receive data), DTR (data terminal ready), and RTS (request to send) lines to provide power.For fully duplexed operation, the host's communications port should be set up so that its RTS is off (at negative voltage). Halfduplex operation can use the host's TXD negative voltage, available through D6, to run the circuitry. Sending a low bit (space state) to the host is just the opposite. This time, the required positive voltage is supplied from the host via diodes D2 and D3, and is routed through Q1 and D1 to DB9-2.

thankx much it's really informative all that you wrote there is question can i use it as serial to USB adapter & how can I found Tx Rx through this it's complete circut with six wires as blue orange green yellow and white
Hope you defintly have an idea to use it for such purpose thanx again