Epson EQUITY 386/33 PLUS - Manual (Page 65)

A jumper’s setting is determined by where the jumper is placed
on the pins. It connects either pin A and the middle pin
(position A) or pin B and the middle pin (position B), as shown
below.
position A position B
A
A
To move a jumper from one position to the other, use
needle-nose pliers or tweezers to pull it off its pins and gently
move it to the desired position.
Caution
Be careful not to bend the jumper pins or damage any
surrounding components on the main system board.
Installing and Removing Options 4-5