From: joe@user.com   
      
   "thewises"  wrote in message   
   news:Xns97A2DF0705006thewisesenternet@198.186.192.136...   
   > I've heard that when you turn a computer on(or turn it off), a power surge   
   > goes through the floppy drives that will damage disks that are in them. I   
   > heard that this can happen with _any_ computer.   
      
   While it is good practice, it's not that 'all' drives will do this.  It all   
   depends   
   on power sequencing in the drive itself.   
      
   When power changes, either up or down, the problem can occur when   
   'write' signals are in a state that enables them as the detect for the   
   enable is also in a state that allows the write.  The combination means that   
   for a short instant, there could be a field applied to the head.   
      
   This does NOT happen on all drives.  In fact, on most of the drives that   
   have 'intelligent' circuitry, this does NOT happen.  I would venture to say   
   that on all modern drives, this is as close to impossible to happen as you   
   can say unless there is a failure on the drive.   
      
   With older drives this is further complicated by the fact that most signals   
   are 'active low' on a drive interface.  If you turn the drive on, and the   
   interface is off or 'low', guess what?  Yeah, there usually are protections   
   for that.  Somewhat.  Speaking of which, know what happens if you   
   turn on a Model II computer with a diskette in the drive and the drive   
   bay attached but turned on?  Well, nothing if it's the 'second generation'   
   FDC card, but the first version paralleled all the floppys, and the bay   
   being off meant the write gate was pulled low and the 800 Shugart had   
   no protections...   
      
   In the 'older' days, I would not have left an 'only copy' of a disk in a   
   drive.   
   But it wasn't that bad.   
      
   Even with the best of protections, spikes can happen.  The worst is when   
   power goes off and on, and the power supplies didn't 'drain' themselves   
   totally off, so the POR circuits don't come up from a known off state.   
   That can wreak havoc.  So I built a 'latching on' power strip.  It was just   
   a power strip with an on and an off button.  The strip had a relay that to   
   activate you pressed an 'on' button.  When the relay closed, it would now   
   power itself on.  If power went off, the relay would open and the system   
   would go off.  And stay off.  Until you pressed the 'on' button again.  To   
   manually turn it off, the 'off' button just broke the connection.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)