From behind, you can see all the connectors. From the top: Keyboard (purple), Mouse (green), 2 x USB, 1 x LAN, Serial (green), Parallel (red), Video (blue), Audio Out (green), Audio In (blue), Microphone (red), Game (yellow). At the bottom, you can see an orange connector - that's the audio S/PDIF digital output. Below that there are two more USB ports provided on a special D-bracket that has four LEDs for bootup diagnostics.