INT 10,9 - Write Character and Attribute at Cursor Position

AH = 09

AL = ASCII character to write

BH = display page (or mode 13h, background pixel value)

BL = character attribute (text) foreground color (graphics)

CX = count of characters to write (CX >= 1)

returns nothing

- does not move the cursor

- in graphics mode (except mode 13h), if BL bit 7=1 then

value of BL is XOR'ed with the background color