INT 2F - HyperDisk v4.50+ - GET CURRENT CACHE STATE
        AX = DF01h
        BX = 4448h ('DH')
Return: AX = 0000h if function supported
            BX = number of cache buffers in use
            CX = number of cache buffers which have been modified
            DL = caching flags (see below)
Note:   AH=DFh is the default; if it is already in use by some other program,
          HyperWare programs then scan multiplex numbers from C0h through FFh
SeeAlso: AX=DF00h,AX=DF02h

Bitfields for caching flags:
 bit 0  staged writes enabled for floppy disks
 bit 1  staged writes enabled for hard disks
 bit 2  writes verified on floppy disks
 bit 3  writes verified on hard disks
 bit 4  reserved (0)
 bit 5  reserved (0)
 bit 6  floppy caching enabled
 bit 7  all caching functions enabled

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