Epson 3865X Plus - Manual (Page 126)

Once you have determined where to add the memory modules,
follow these steps to install them:
1. Remove the cover. See page 5-2 for instructions.
2. Turn the computer so that the front panel is facing right
and the back panel is facing left. The SIMM sockets are
located on the main system board just above the option
slots, as shown below.
SlMM
\
option slots
5-20 Installing and Removing Options