Format of Matrox-specific VESA extensions information:
Offset	Size	Description	)
 00h  7 BYTEs	signature "VBE/MGA"
 07h 10 BYTEs	??? (01h 01h 00h 00h 00h 00h 00h 00h 00h 07h)
 11h	WORD	BIOS version (high byte = major, low byte = one-digit minor)
 13h	DWORD	-> manufacturer name (ASCIZ "Matrox")
 17h	DWORD	-> ASCIZ card name
 1Bh	DWORD	-> ??? ASCIZ string (empty string on card examined)
 1Fh	DWORD	-> ASCIZ vendor name
 23h	DWORD	-> ASCIZ BIOS file base name
 27h	DWORD	-> PINS
 2Bh	WORD	video memory size in 64K units
 2Dh	DWORD	linear address of linear frame buffer
 31h	DWORD	linear address of MGA control aperture
 35h	WORD	PCI bus/device for card???
 37h 201 BYTEs	unused??? (cleared to 00h)