Interrupt 67h	Expanded Memory Specification
Function  46h   Return Version Number
entry	AH	46h
return	AH	status
		00h	successful completion
	AL	version number
		32h	EMS 3.2
		40h	EMS 4.0
REF: Programmers Journal Vol 9.2 Pg 75
A program cannot assume that a PC supports EMS until it checks for a driver. In
an assembly language program, the check is easy: grab interrupt vectory 67h,
use 000Ah instead of the offset from the interrupt vector, and then look for
the eight-character tag EMMXXXX0.
If the tag is there, invoke interrupt 67h with AH=46h. If AH equals zero on
return from the interrupt, then register AL holdes the EMS driver version
number. The two common version are 32h and 40h.
GetEMSVer Proc
    mov  al, 67h
    call GetVector	 ;Int\21f\35
    mov  ax, es
    mov  ds, ax
    mov  si, 0Ah
    lodsw
    cmp  ax, 'ME'
    jne  gev1
    lodsw
    cmp  ax, 'XM'
    jne  gev1
    lodsw
    cmp  ax, 'XX'
    jne  gev1
    lodsw
    cmp  ax, '0X'
    jne  gev1
    mov  ah,46h
    call DoEMSFunc	 ;Int\67 -Function  46h
    jnc  gev2
gev1:
    xor  ax,ax
    stc
gev2:
    ret
GetEMSVer endp