This circuit board fixes the miswired IDE (ATA/PATA) adapter on the motherboard of Emerson's 500EC, 4412, and Scott 2000SC12. It corrects bits 8-15 being mirrored and lets you mount a drive from this computer on another, and vice-versa. If you do not have this issue, or one of these model computers, do not buy this. 

Before installing, it is imperative that you BACK UP YOUR DATA FIRST. Any data already on the 286's drive will be inaccessible on the machine with the adapter installed. To install, remove the 3.5" floppy drive and connect the adapter to the IDE connection on the motherboard. The solder side of the adapter faces the RAM. Then connect the IDE cable and reinstall the floppy drive.

While you could in theory use this adaptor to connect a drive from your 286 to another PC by connecting it between the drive and a USB to PATA adapter, this in not advised as this adaptor does not maintain the screw and capacitance requirements of later faster ATA controllers.

Pin 1 on the adaptor is the corner marked in white.  The white stripe indicates the polarization tab.