Something

program test;

type
  rec = record
    a: integer;
    b: string;
  end;

procedure print_rec(var r: rec);
begin
  writeln('a: ', r.a, ' b: ', r.b);
end;

var
  f: file of rec;
  i: integer;
  r1, r2: rec;

begin
  assign(f, 'test.dat');

  reset(f);
  for i := 1 to 10 do
  begin
    r1.a := i;
    r1.b := 'foo';
    write(f, r1);
  end;

  reset(f);
  for i := 1 to 10 do
  begin
    read(f, r2);
    print_rec(r2);
  end;

  close(f);
end.