INT 2F - SMARTDRV v4.00+ - INSTALLATION CHECK AND HIT RATIOS
        AX = 4A10h
        BX = 0000h
        CX = EBABh (v4.1+; see Note)
Return: AX = BABEh if installed
            DX:BX = cache hits
            DI:SI = cache misses
            CX = ???
            BP = version in BCD (4.10 = 0410h)
Notes:  most of the SMARTDRV API, including this call, is supported by
          PC-Cache v8.0
        if DBLSPACE.BIN is installed but SMARTDRV has not yet been installed,
          unless CX=EBABh on entry, DBLSPACE.BIN displays the error message
          "Cannot run SMARTDrive 4.0 with DoubleSpace" and aborts the caller
          with INT 21/AX=4C00h
        SMARTDRV v3.x had a completely different API using IOCTL calls
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"

.