Epson 486SX - Manual (Page 120)

3. Gently push the SIMM into the socket and then tilt it left
until it is vertical.
The SIMM should snap into place between the tabs and the
retaining posts. If it does not go in smoothly, do not force it;
pull it all the way out and try again.
Make sure the SIMM is fully inserted into the socket and
that the pins on the retaining posts extend through the
holes in both ends.
4. Repeat steps 2 and 3 for each SIMM you want to install.
5. Set the appropriate main system board jumpers to indicate
the total amount of memory you now have. See “Jumper
Settings” on page 6-4 for instructions.
6. Reinstall the memory card as described on page 6-19.
Installing and Removing Options 6-17