MON 

 Process 

 0 

 Do not change the MSB of the pixel data on the frame buffer. 

 1 

 Set MSB of pixel data in frame buffer to 1 

Shadow when VDP2 is in a mode that uses shadow (decreases the brightness of the pixel data on the scroll plane) or window (displays another plane in the specified area) and the most significant bit (MSB) is 1. , Do window processing.
∙ Set MSB to 1 (on) for pixels already drawn in the frame buffer. The color code is valid only when the frame buffer is a color bank code (because the MSB is used for shadow enable and window enable on the VDP2 side, there is no RGB identification bit). Color calculation is not possible. Specify replace for color calculation.
In the case of texture parts, the original picture data is used only when there is no pixel (transparency, end code is no pixel, other is there), so the color code can be used with either RGB code or color bank code . For non-textured parts, the non-texture color is not reflected in the drawing.
⿟ When MSB ON is set to 1, do not specify color operation (replace). Please note that when MSB ON is 1, color calculation has no meaning and only processing time is significant.
¡MSB is turned on for meshed parts.
The following is an example of MSB on.

Figure 6.16 MSB on