This panel is located on the right side of the cockpit, slightly behind the seat. That location makes the keyboard switch panel rather difficult to reach, but real estate is scarce in a cockpit, and this panel does not see too much use anyway.
The mixer panel offers the posibility to mix the audio signals from various PCs and output them to the headset. The connector for the headset jack is also located here.
In the days of Win 98 the keyboard switcher provided keyboard hot-swap capability between up to 8 PCs. The top switch toggles between two groups of 4 PCs. The two rotaries below each select one of 4 PCs.