The 5 was a cut down AX-7 - possibly? without the backlit display, and from the late 80s. The 7 came before the KN800 which would be around 1988 and was one of the first pcm sample boards with sample swapping in the editing. The 5 possibly? did not have the editing features, I can't remember for sure. Considering the accomp tracks and polyphony compared to today's boards it is steep, no general midi and probably? no disk drive. All this from memory so don't quote me.