Thanks for the link, Roy. Note that both types have 10 jumper pins. The components are simply "re-arranged" so that the PCB fits the intended applications. AFAIK, the XEGS and the 1200XL are the exact same adapter. The linked picture is a better picture than is in the install docs (fuzzy!), so it is likely like this:
Of course, the 4 pins on this side are for the 3 connection wires. Probably
, the left two pins on the other side are the internal/external power selection.
The next two pins to the right are probably
the rescue jumper pins.
The activity LED pins are probably
the two vertical pins barely visible over the flash chip holder.
Now, if I can get rid of the "probably"...
But doesn't that just plug into the existing (OS socket) Machine chip holder. With three wires to be soldered to motherboard.http://www.atarimax.com/myide_old/documentation/
Try this link to refresh memory... not like the 1200xl at all.