program moveboot;
type
    byte = -128..127;
    diskblocks = array[1..512] of byte;
    quikload = record
                   header: array[1..12] of byte;
                   a: array[1..4] of diskblocks;
                   end;
var
    blkno: longint;
    i,x: integer;
    fnDest,fnSrc: string[20];
    f1: file;
    f2: file of quikload;
    FourBlocks: quikload;

begin
write('Enter file name to write blocks: '); readln(fnDest);
write('Enter file name to get boot blocks: '); readln(fnSrc);
write('Enter block number in ',fnDest,' to write boot blocks: '); readln(blkno);
reset(f1,fnDest);
reset(f2,fnSrc);
read(f2,FourBlocks);
for i := 1 to 4 do
   begin
   x := blockwrite(f1,FourBlocks.a[i],1,blkno);
   if (ioresult <> 0) or (x <> 1) then
      begin
      writeln('Write of block ',blkno,' failed.');
      close(f1,lock);
      close(f2,lock);
      exit(moveboot);
      end
   else blkno := blkno + 1;
   end;
close(f1,lock);
close(f2,lock);
end.