Samsung LS21BRBAB-XAA - Manual (Page 13)

POWER S/W
: Switch the monitor on and off.
POWER IN
: Connect the power cord for your monitor to the POWER IN
on the back of the monitor.
DVI IN (Source List : Digital) :
Connect the DVI cable to the DVI IN port
on the back of your monitor.
RGB IN (Source List : Analog) :
Connect the signal cable to the 15-pin,
RGB IN port on the back of your monitor.
VIDEO (Source List : Video)