SCREEN                   Character at Specified Location             Function

 y = SCREEN(row, column [,z])

    Returns the ASCII or color information about a specified screen
    location.

     row,col    Absolute coordinates of a screen location. row must be in
                the range 1 to 25, and col must be in the range 1 to 80.

           z    If omitted or 0, SCREEN returns the ASCII value of the
                character at row, col. If nonzero, causes SCREEN to return
                the character attribute, attr, a value in the range 0 to
                255. The attribute can be interpreted as follows:

                   Foreground color = attr MOD 16

                   Background color = ((attr - foreground)/16) MOD 128

                If attr is larger than 127, the character is blinking.
                See the COLOR statement for a list of colors.

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      Notes:    In graphics mode, if no recognizable character is at
                row,col, SCREEN returns 0.

                The z argument is valid only in text mode.