function access(var Name: ArgString; Mode: integer): integer;
  extern;

function open(var Name: ArgString; Mode: integer): integer;
  extern;

function read(Descriptor: integer; var Buffer: FileBuffer;
              NBytes: integer): integer;
  extern;

function write(Descriptor: integer; var Buffer: FileBuffer;
               NBytes: integer): integer;
  extern;

function lseek(Descriptor: integer; Offset: integer;
               Whence: integer): integer;
  extern;

function close(Descriptor: integer): integer;
  extern;