INT 10 - VIDEO - READ BLOCK OF DAC REGISTERS (VGA/MCGA)
        AX = 1017h
        BX = starting palette register
        CX = number of palette registers to read
        ES:DX -> buffer (3 * CX bytes in size) (see also AX=1012h)
Return: buffer filled with CX red, green and blue triples
SeeAlso: AX=1015h