These functions are preferred over the superseded FCB File I/O functions
unless you must maintain compatibility with DOS 1.0.

3cH create file                       5bH create new file (must not exist)
3dH open file                         5aH create unique/temporary file
3eH close file                        6cH extended create and open
41H delete file

42H move read/write pointer (also use to get file size)
3fH read from file or device
40H write to file or device
68H commit file data (flush buffers to disk)

4406H check for EOF (input status)    4400H see if handle is device or file
4407H check for busy (output status)  440aH see if file is on network drv

45H duplicate file handle             67H set (increase) maximum handles
46H redirect file handle I/O

Handle-Oriented File I/O