Source : Free On-Line Dictionary of Computing

Single In-line Memory Module
     
         (SIMM) A small circuit board or substrate, typically
        about 10cm x 2cm, with {RAM} {integrated circuits} or die on
        one or both sides and a single row of pins along one long
        edge.  Several SIMMs are mounted with their substrates at
        right-angles to the main circuit board (the {motherboard}).
        This configuration allows greater packing density than direct
        mounting of, e.g. DIL ({dual in-line}) RAM packages on the
        motherboard.  In 1993 one SIMM typically held one or four
        megabytes, by early 1997 one could hold 8, 16, or 32 MB.
     
        (1997-01-05)