INT 62 u - FGDRIVER v4.02 - "FG_VBDEFINE" - CREATE VIRTUAL BUFFER
	AX = 00D1h
	ES:BX -> memory block for virtual buffer
	CX = buffer width in pixels
	DX = buffer height in pixels
Return: AX = virtual buffer handle
	    FFFFh on error
Notes:	the FGDRIVER functions are rearranged with each major release, but
	  their parameters do not change (see #03474)
	the application-provided buffer must be large enough to hold CX*DX
	  bytes
SeeAlso: AX=00CCh,AX=00CDh,AX=00CEh,AX=00D2h,AX=00D4h,AX=00D5h