Moose wrote:
On Mar 23, 5:33 pm, "Michael J. Mahon" <mjma...@aol.com> wrote:Aside from disks, by far the biggest cause of disk errors is a dirtyor slightly misaligned drive head, or an off-speed drive.Or even a fault on the Apple ]['s motherboard. Just about every time one of my Apple ]['s motherboards broke down / developed a fault, it always seemed to turn the drive into a disk erasing / chewing machine. Not a good thing .... ;)
I'm happy to have never seen that problem. ;-) Since any disk writing is done from RWTS in RAM, an "erasing machine" requires that RWTS blow up between starting a valid write and finishing it, which results in erasing the entire track. The Disk II Controller is cleverly designed to require a little "dance" to enable writing, making it unlikely that a random series of softswitch accesses could cause trouble. Since the 'write' line is a hardware line from the drive, some failures of the controller or drive could also result in energizing the write/erase head... -michael NadaNet 3.1 for Apple II parallel computing! Home page: http://home.comcast.net/~mjmahon/ "The wastebasket is our most important design tool--and it's seriously underused."