Re: Thunderbolts and Lightning

[w_tom <w_tom1@usa.net>]

  In those early days, thermal changes could easily cause a
drive to vary.  For example, which floppy head did not read?
We had seen this even on hard drives.  But in those days, we
aligned heads to fix this kind of problem.  On some hard
drives, metal used to hold head would actually change length
with use and eventually restore to original length of a days
time.

  There are too many possible reasons for your problem. 
Without actual data, we can only speculate.  Maybe even a
missing or failed pull-up resistor causing a line to float in
and out of an acceptable logic state.  Found that to be a
problem on this monitor.  Replaced the resistor. It now starts
up every time.  But electricity in the air never was a problem
with TTL electronics.


Simon Williams wrote:
> 
> Any other transient effects that could be to blame (UFO activity?).
> Seems odd that an entire batch of disks would be non-functional one
> day and work fine the next...