Epson 3865X Plus - Manual (Page 128)

4. Hold the SIMM in your hand so that the component side of
the SIMM is facing to the left (toward the back of the
computer) and the metal connector pins are facing down.
5. To insert the SIMM in the socket, place it on the right side
of the tabs at a 45° angle, as shown below.
5-22 Installing and Removing Options