These mechanical adapter PCBs allow the use of PC104 and Vortex86DX X-ISA single board computers on an ISA backplane.
Such adapters are available commercially for industrial use at extreme prices (100$+), for simple passive adapters.
Vortex86DX, connected to an ISA backplane, with a TVGA9000 video card, Aztech sound card and CF storage, playing DOOM: