This module provides functions for manipulating the current directory on
disks, and disk like devices. It is based on the Windows direct.h header.

At the beginning of the program use the directives

  #include <fileio.h02>
  #include <direct.h02>

The following functions are defined:

   n,e = getcwd(d,&s);  Read the current directory on device d into 
                        string s, returning the length of the directory 
                        name in n and error code e.
                        
                        The device specifier d consists of the drive number
                        and disk number combined by the | operator.
                        
                        If the length of the name is 0, there is no current
                        directory or there was an error.

   r,e = chdir(d,&n);   Change the current directory on device d to the
                        directory name n, returning result code r and 
                        error code e.
                        
                        The device specifier d consists of the drive number
                        and disk number combined by the | operator.
                        
                        A result code of 0 indicates success, while any 
                        other value indicates failure.

   r,e = mkdir(d,&n);   Create directory with name n on device d, returning 
                        result code r and error code e.
                        
                        The device specifier d consists of the drive number
                        and disk number combined by the | operator.
                        
                        A result code of 0 indicates success, while any 
                        other value indicates failure.

   r,e = rmdir(d,&n);   Remove directory with name n from device d, 
                        returning result code r and error code e.
                        
                        The device specifier d consists of the drive number
                        and disk number combined by the | operator.
                        
                        A result code of 0 indicates success, while any 
                        other value indicates failure.

   d,e = getdrv();      Returns the current drive/disk identifier in d 
                        error code e. 
                        
                        The disk/drive identifier d consists of the drive 
                        number and disk number combined by the | operator. 
                        
                        If the returned identifier is 0, an error occured.
                        
   r,e = chgdrv(d);     Returns the current drive/disk to d, returning
                        result code r and error code e. 
                        
                        The disk/drive identifier d consists of the drive 
                        number and disk number combined by the | operator. 
                        
                        A result code of 0 indicates success, while any 
                        other value indicates failure.

   n,e = drvnam(d);     Return single character drive name r for disk/drive
                        identifier d and error code e. 
                        
                        The disk/drive identifier d consists of the drive 
                        number and disk number combined by the | operator. 
