Source : Free On-Line Dictionary of Computing

dual ported
     
        A term used to describe memory {integrated circuit}s which can
        be accessed simultaneously via two independent address and
        data busses.
     
        Dual ported memory is often used in {video display} hardware,
        especially in conjunction with {Video Random Access Memory}
        (VRAM).  The two ports allow the video display hardware to
        read memory to display the contents on screen at the same time
        as the CPU writes data to other areas of the same memory.  In
        single-ported memory these two processes cannot occur
        simultanteously, the CPU must wait, thus resulting in slower
        access times.  {Cycle stealing} is one technique used to avoid
        this in single-ported {video memory}.
     
        (1995-01-12)