On the shelf above the 781 you see a homebrew band decoder. It is driven by the band switch of the respective radios. Change bands on the radio and the antennas switch to the appropriate band, and the computer follows as well.
To the left of the keyboard you see an old Ekletech remote tuning knob. This tunes the second radio (781). I mostly CQ on the bottom radio and tune for S&P on the top.
The software/keyboard control which radio transmits. The receiver (top, bottom or both [one in each ear]) are accomplished from a switch on the YCCC SO2R controller, which is the low profile black box at desk height just to the left of the 7800.
All of my antennas and stubs are switched in my switch hut, which is located outside my shack. This is where all of the coaxes from my individual antennas come in. From my shack to my switch hut I run two heliax pieces (one for each radio) as well as all of the control cable.
The rest of the picture has various rotor controls, watt meters and homebrew switches for selecting antennas, as well as the stack controllers. These switches all control relays either on the towers or in the switch hut.
That about it. Hope its useful.