procedure Readback (const f: integer; var Line: String; var _bof: boolean);
const
  MAXLINELENGTH = 256;
var
  curr,
  Before : Longint;
  Buffer : array [0..MAXLINELENGTH] of char;
  p      : PChar;
begin
  // scan backwards to the last CR-LF
  curr := FileSeek (f, 0, 1);
  Before := curr - MAXLINELENGTH;
  if Before < 0 then
    Before := 0;
  FileSeek (f, Before, 0);
  FileRead (f, Buffer, curr - Before);
  Buffer[curr - Before] := #0;
  p := StrRScan (Buffer, #10);
  if p = Nil then
  begin
    Line := StrPas (Buffer);
    FileSeek (f, 0, 0);
    _bof := True
  end
  else
  begin
    Line := StrPas (p + 1);
    FileSeek (f, Before + Longint (p) - Longint (@Buffer), 0);
    _bof := False
  end;

  // this will also work with Unix files (#10 only, no #13)
  if length (Line) > 0 then
    if Line[length (Line)] = #13 then
    begin
      SetLength (Line, length (Line) - 1)
    end
end;


procedure TForm1.FormCreate (Sender: TObject);
const
  FileName = 'c:\delphi3\bin\unit1.pas';
var
  f           : integer;
  Line        : string;
  BeginOfFile : boolean;
begin
  f := FileOpen (FileName, 0);
  // move to end of file!
  FileSeek (f, 0, 2);

  // read all lines, backwards
  repeat
    Readback (f, Line, BeginOfFile);
    ListBox1.Items.Insert (0, Line);
  until BeginOfFile;

  FileClose (f);
end;