Int 2F Fn 4A11  - Dblspace.bin - "dssetentrypoints" - Set Device Driver E  [d]

   AX = 4A11h
   BX = 0004h
   CL = drive number (0=A:) of compressed drive
   DL = unit number for new driver entry points
   DH = 00h
   ES:SI -> device driver strategy routine to call for drive
   ES:DI -> device driver interrupt routine to call for drive

Return: CL = FFh on error (not a compressed drive)
   BX destroyed
Program: DBLSPACE.BIN is the resident driver for DoubleSpace, the
     disk-compression software bundled with MS-DOS 6.0

Note:  in conjunction with subfunction 0003h, this call allows disk caches
     like SMARTDRV to apply a device driver wrapper to DoubleSpaced
     drives just like SMARTDRV applies to regular block devices

See Also: AX=4A10h/BX=0007h,AX=4A11h/BX=0000h,AX=4A11h/BX=0003h