@domi @mei Yeah, they had some crazy tales about the 3.5" diskette redesign on the Mac. Of course, there's a trade off. Moving more work to an OS routine means taking RAM away from other things, and in the mid-80a, RAM was pretty precious. The other thing is those disk IO routines basically monopolize the system, so nothing else can be done until disc accesses complete. You can, in fact, lock up everything during disk access, and there's no way out but a hard reset while the disk is in use.