CR42
unsigned char CR40, CR41, CR42, CR43, CR45;
reg->CR42 = 0x20;
reg->CR42 = 0x00;
vga_out8(0x3d5, reg->CR42, par);
reg->CR42 = vga_in8(0x3d5, par);
vga_out8(0x3d5, reg->CR42, par);
{VIACR, CR42, 0xFF, 0x00},