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  Description
 
    The HighVideo procedure changes the foreground color by turning on
    the high-intensity bit in TextAttr. The LowVideo procedure turns
    off high intensity. The current display remains unchanged. Any
    subsequent text output is in the high- or low-intensity form of
    the previous foreground color.
 
    TextAttr, defined in the Crt unit, holds the current foreground
    color in bits 0-3. The possible values lie in the range 0..15.
 
    Bit 3 controls intensity. HighVideo sets bit 3, and LowVideo clears
    it. Turning bit 3 on adds 8 to the value held in bits 0-2. Thus,
    the possible values for foreground color fall into two ranges.
 
    Colors with values in the range 0..7 are low-intensity. Those
    in the range 8..15 are high-intensity. The Crt unit defines the
    values as constants that can be passed to the TextColor procedure.
    TextColor is another procedure for setting a new foreground color.
 
    If the current text color is already high-intensity, HighVideo has
    no effect. If the current text color is already low-intensity,
    LowVideo has no effect.
 
    If the new text color matches the current background color, the
    character output is invisible.