johnhlee@cory.Berkeley.EDU (John Lee) (04/16/89)
In article <5277@cs.Buffalo.EDU> ugkamins@sunybcs.UUCP (John Kaminski) writes: >Oh, BTW, I was wondering if write protect is harware or software enforced. I >had the ("lowly") Timex/Sinclair 2068 and something called a MikroDrive for [...] >tape after doing what I wanted. The write protection was strictly managed in >software by reading the status of another port, which had a bit of that port >connected to a lever switch. Without trashing one of my disks, is it possible >to program the disk DMA, start the motor, etc. and write the disk with the >tab on "protect?" I am pretty sure on IBM-PC drives, the controller chip >refuses to do it and puts a write-protect into its status register, thereby >making write-protect more-or-less hardware enforced. The only way you could >do it is to change the firmware or microprogramming of the controller. >What say you in netland? The CBM drives and most floppy disk drives (that I know of) enforce the write-protect *on the drive*; i.e., regardless of what the computer and drive controller tells the drive to do, the drive will *not* write on a write-protected disk. But let me qualify that. On my Heathkit H-89 computer (does anyone else know what this is? I still like this little outdated thing), one of my drives is an Wangco-Siemans single-sided 40 track drive that can be customized using jumpers and circuit board pads. One of the traces can be cut and jumpered so that the write-protect switch is ignored by the drive and passed on to the controller only. That means that it is up to the controller to handle the write-protect and the drive will happily write on a write-protected disk if told to do so. However, the default was to handle write-protect at the drive. My other drive (a Tandon TM-400) does not have this ability and always enforces write-protect, just like my Amiga disk drives. ------------------------------------------------------------------------------ Raining CATS & DOGS? Join the RATS: Remote Amiga Teleconferencing System. ARPAnet: johnhlee@cory.Berkeley.EDU John Lee UUCP: ...!ucbvax!cory!johnhlee