INT 2F - SMARTDRV v4.00+ - INSTALLATION CHECK AND HIT RATIOS

	AX = 4A10h
	BX = 0000h
	CX = EBABh (v4.1+; see Note), and CX <> 0EDCh
Return: AX = BABEh if installed
	    DX:BX = cache hits
	    DI:SI = cache misses
	    CX = number of dirty cache elements
	    BP = version in BCD (4.10 = 0410h)
		4.0  = 0400h (Windows 3.1)
		4.01 = 0401h (MS-DOS 6.0, 1992/07/30)
		4.10 = 0410h (1992/11/11)
		4.20 = 0420h
		5.0  = 0500h (MS-DOS 6.2)
Notes:	most of the SMARTDRV API, including this call, is supported by
	  PC-Cache v8.0 and recent versions of the Norton Caches
	the internal name for SMARTDRV is "BAMBI", hence the magic "BABE".
	if DBLSPACE.BIN is installed but SMARTDRV has not yet been installed,
	  then calls of this function with CX<>EBABh on entry cause
	  DBLSPACE.BIN to display the error message
	  "Cannot run SMARTDrive 4.0 with DoubleSpace" and abort the caller
	  with INT 21/AX=4C00h
	Since the Novell DOS 7 - DR-DOS 7.03 NWCACHE supports a similar 
	  install check at this function, but the returned registers
	  contain different data, the caller must take the returned AX value
	  into account to ensure proper interpretation of the returned info.
	  The caller should ensure CX <> 0EDCh to avoid any interaction
	  with the NWCACHE and COMMAND.COM special case of CX=0EDCh.
	  Although this is an install check, NWCACHE always flushes delayed
	  writes to disk, when calling this function with CX<>0EDCh or while
	  /FLUSH:ON is active, but this is nothing to rely upon. The reason
	  for this could be to get more accurate statistics, while SMARTDRV
	  just takes a on-the-fly snapshot of the statistic vars.
	The private NWCACHE/NLCACHE install check INT2Fh/D8C0h does not flush
	  to disk, and therefore can be used by callers that must ensure
	  the buffers aren't flushed on this function (e.g. alternative
	  command shells may need this to make their "flush before prompt"
	  feature configurable).
	The NWCACHE 0EDCh special case will most probably vanish with
	  future issues of NWCACHE (2.0+).
	SMARTDRV v3.x had a completely different API using IOCTL calls, which
	  was also supported by the Norton Caches
BUG:	Although DS and ES registers are listed as unmodified, some
	  releases of SMARTDRV seem to trash the DS register, at least the
	  MS-DOS 6.2+ KEYB takes care to preserve the DS register when calling
	  this function.
SeeAlso: AX=4A10h/BX=0001h,AX=4A10h/BX=0004h,AX=4A10h/BX=0005h
SeeAlso: AX=4A10h/BX=0007h,AX=4A10h/BX=1234h,AX=4A11h/BX=0000h
SeeAlso: INT 21/AX=4402h"SMARTDRV",INT 21/AX=4403h"SMARTDRV"