The Cyclone Matrix Mixer routes inputs 1-8 (left to right) to outputs 1-7 (left to right).  Pressing the button in the lower left corner adds input 1 and input 2 together, sending it to output 1.  Pressing the top right button mixes input 7 and input 8 and sends it to output 7.

Since 1+8 and 8+1 are the same thing, there is only need for half the number of buttons.

The Spin input takes a DS (Direct Signal, 0-1) and shifts where the inputs are routed to, similar to how the 5ms Rotating Clock Divider works.