Probier'S mal mit den nativen Dateiroutinen.
Ungefähr so.
Code:
procedure writeByte;
var f : integer;
buffer : byte;
nOffset : integer;
begin
buffer := 0;
nOffset := $1C;
f := FileOpen('datei.xxx', fmOpenWrite);
if f >= 0 then
try
fileSeek(f, nOffset, soFromBeginning);
fileWrite(f,buffer, 1);
finally
fileClose(f);
end;
end;