Fun with degaussers

At 09:50 PM 5/1/99 -0400, Tim wrote: The issue isn't with the disk I don't believe (I don't have an alignment disk to prove it so I can't be sure). The goal of demagnetizing is to recreate a uniform state of non-magnetism on the media. I remember that Jerry Pournelle used to toss disks that were no longer needed but couldn't be given away directly (because they had commercial software on them) into a bin with a couple of those huge "fishing" magnets. Once treated in this way they were not readable, and not usable until demagnetized. At the time it was explained that the erase heads write a narrower path than the read heads scan so if the track has been magnetized on the outside it can interfere with the reading and writing of a block. Then again, it could all be hogwash, but using the demagnetizer on the disks did the trick. Other empirical evidence was accumulated when the demagnetizer shut itself off while I was using it near the disk, (thermal shutdown to prevent meltdown I guess). That disk was unusable until the demagnetizer reset and I could use it more carefully. --Chuck