INT 10 - VIDEO -  Video7 VGA,VEGA VGA - GET VIDEO MEMORY CONFIGURATION
        AX = 6F07h
Return: AL = 6Fh
        AH = bits 0-6 = number of 256K blocks of video memory
             bit 7    = DRAM/VRAM (0: DRAM, 1: VRAM)
        BH = chip revision (SR8F) (S/C Chip in VEGA VGA)
        BL = chip revision (SR8E) (G/A Chip in VEGA VGA)
        CX = 0000h