External Connections to IRLP Interface Board.  They are mounted in knockouts that were already in the back of the computer case.

The green arrows are the audio connections to the computer's sound card.  These provide the audio to and from the radio.  The RX audio is also going into the IRLP Interface Board so that it can decode any received DTMF commands.

The Red arrow is the radio connections to the IRLP Interface Board.  This is a DB-9 that has TX and RX audio as well as PTT and COR.

The Blue arrow is the connection between the computer parallel port and the IRLP Interface Board.  This provides the signaling for PTT to the card, decoded DTMF info to the computer and also provides the capability to turn on and off the three auxillaries on the IRLP Interface Board (not currently used on 3118).