Int 10 Fn 4E00  - Vesa Xga Bios Extensions - Get Xga Environment Informat  [V]

   AX = 4E00h
   ES:DI -> 256-byte buffer for XGA information (see #0067)

Return: AL = 4Eh if function supported
       AH = status
       00h successful
       else error code
Desc:  determine whether VESA XGA extensions are present and the capabilities
     supported by the display adapter

See Also: AX=4E01h,AX=4E02h,AX=4F00h
Index: installation check;VESA XGA

Format of XGA information buffer:
Offset Size    Description (Table 0067)
 00h  4 BYTEs  signature ("VESA")
 04h   WORD    VESA version number
 06h   DWORD   pointer to ASCIZ OEM string
 0Ah   DWORD   environment flags (see #0068)
 0Eh   WORD    number of XGA adapters installed (other VESA XGA functions
         require a handle indicating which adapter to use)
 10h 240 BYTEs reserved

Bitfields for XGA environment flags:
Bit(s) Description (Table 0068)
 0-1   system bus (00 = MCA, 01 = ISA, 10 = EISA)
 2 bus mastering available
 3-31  reserved