DO NOT ask why this is called Ionarc... I forgot after the years, and even if I remembered what it was, it would most likely be quite embarrassing. The long rows of headers are essentially unused - this module was part of a stack of PCBs, actually the base board of a small computer.
I am putting it here because I've used it quite a bit for debugging my CPU projects. The wires go to the RES, CLK and data bus lines and allow me single step and see what's on the bus in hex or decimal.
The jumper is there to choose between the single-step (CLK) push button, or you can use the multiplex signal for the 7-segment display as a clock.