Samsung ML-2251NP - Manual (Page 180)

I NSTALLING P RINTER O PTIONS E.3
E
Installing Memory DIMM
Additional printer memory is provided on DIMM (Dual In-line
Memory Modules).
1 Turn the printer power off and unplug all cables from the
printer.
2 Remove the two screws on the back of the printer.
3 Open the control board cover.