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  Description:  IOCTL: Generic I/O Control for Block     DOS 3.2 Only
                Devices
 
  Provides a general-purpose mechanism for communication between applica-
  tion programs and block device drivers. Allows a program to inspect or
  change device parameters for a logical drive and to read, write, format,
  and verify disk tracks in a hardware-independent manner.
 
  Input                                     Output
  ══════════════════════════════            ══════════════════════════════
  AH=44H                                    If function successful
  AL=0DH                                    Carry flag=clear
  BL=drive code (0=default,                 and, if called with CL=60H or
      1=A, 2=B, etc.)                        61H
  CH=category (major) code:                 DS:DX=segment:offset of para-
     08H = disk drive                        meter block
  CL=function (minor) code:                 If function unsuccessful
     40H = Set Device Parameters            Carry flag=set
     41H = Write Track                      AX=error code
     42H = Format and Verify
            Track
     47H = Set Access Flag
     60H = Get Device Parameters
     61H = Read Track
     62H = Verify Track
     67H = Get Access Flag
  DS:DX=segment:offset of para-
         meter block
                                    -♦-