Samsung ML 2250 - Manual (Page 175)

I NSTALLING P RINTER O PTIONS D.4
4 Locate the memory DIMM slot (the upper slot) and the PS
DIMM slot (the lower slot) on the control board. They are
not interchangeable.
To install the memory DIMM, continue with Step 5.
To install the PS DIMM, go to Step 6.
5 Hold the memory DIMM so that the notch and the
connection point are aligned with the slot as shown, and
insert it all the way into the upper slot.
PS DIMM
Memory
DIMM