Changes

* In bitmap mode, R48 Write mask is used for VRAM0 and R49 directly related to which VRAM is written to.* FC low then FC high are used for VRAM1to write pixels. For example, if R48 The order is set to #34 not reversed when DIX=1.e.g. When 8bpp, fc=&1234, DIX=0 and R49 is set to #nx=4 then after LMMV has executed we will see the bytes in vram: &34,&12, and &34,&12.When 8bpp mode is used, xfc=0 will be set to #34&1234, xDIX=1 and nx=4 then after LMMB has executed we will be set to #see the bytes in vram: &12, &34,&12,&34.* FC bits do not correspond directly to physical VRAM but do match the pixels in each byte.e.g. if x=2 0, 4bpp,fc=&1234 and nx=4 we will be set to #see in vram &34 etc,&12. This is why the documentation states that for 8bppIf x = 1, 4bpp , fc=&1234 and 2bpp modes you should repeat nx=4 we will see in vram &x4,&32,&1x where 'x' is the pixels through R48 and R49 to ensure a consistent fill valuedata that is already in vram.  Both of these explain why it is best that FC is filled with the same data for each pixel.