I have a Mac SE I picked up a while ago with a General Computer Hypercharger 020 however I haven't been able to find anything saying what the jumpers are for or what the 50 pin header on the back connects to.

While I managed to find the extension for it, I have not been able to find what the jumpers do, less yet a manual. Does anyone have any idea where I might be able to track down a manual or guide for it?