> I don't see any great difference in both cables except for that one pin > being closed. > > Also in my drive the pin which is blocked in the 80 pin connector is > absent. So how the cable change is going to make any difference ? Google and wikipedia are your friends ;) http://en.wikipedia.org/wiki/Parallel_ATA#Parallel_ATA_interface The parallel interface is being replaced by a serial interface but the wikipedia page is still a good read, there are still lots of old machines using only the parallel interface so it's good to know these things.