Horiz pixel panning    index 13h  ATTRIB

Layout  b3-b0  HPP  Horizontal pixel panning

- Horizontal pixel panning (bits 3-0)
        The number of pixels to shift the video data horizontally to
        the left. This affects the starting far left pixel and the
        ending far right pixel on the screen. It is used in
        conjunction with the starting address for smooth panning
        operations.

             b3-b0      Number of pixels shifted to the left
                        0+,1+,2+     13h     Other modes
                        3+,7,7+
             0          1            0       0
             1          2            1       -
             2          3            2       1
             3          4            3       -
             4          5            4       2
             5          6            5       -
             6          7            6       3
             7          8            7       -
             8          9            -       -