magic smoke

2 definitions found

magic smoke - Free On-line Dictionary of Computing (26 May 2007) :

  magic smoke
  
     <electronics, humour> A substance trapped inside integrated circuit
      packages that enables them to function (also called
     "blue smoke"; this is similar to the archaic "phlogiston"
     hypothesis about combustion).  Its existence is demonstrated
     by what happens when a chip burns up - the magic smoke gets
     let out, so it doesn't work any more.
  
     See Electing a Pope, smoke test.
  
     Usenetter Jay Maynard tells the following story:
  
     "Once, while hacking on a dedicated Zilog Z80 system, I was
     testing code by blowing EPROMs and plugging them in the
     system, then seeing what happened.  One time, I plugged one in
     backward.  I only discovered that *after* I realised that
     Intel didn't put power-on lights under the quartz windows on
     the tops of their EPROMs - the die was glowing white-hot.
     Amazingly, the EPROM worked fine after I erased it, filled it
     full of zeros, then erased it again.  For all I know, it's
     still in service.  Of course, this is because the magic smoke
     didn't get let out."
  
     Compare the original phrasing of Murphy's Law.
  
     [Jargon File]
  
     (1995-01-25)
  

magic smoke - Jargon File (4.4.4, 14 Aug 2003) :

  magic smoke
   n.
  
     A substance trapped inside IC packages that enables them to function
     (also called blue smoke; this is similar to the archaic phlogiston
     hypothesis about combustion). Its existence is demonstrated by what
     happens when a chip burns up -- the magic smoke gets let out, so it
     doesn't work any more. See smoke test, let the smoke out.
  
     Usenetter Jay Maynard tells the following story: "Once, while hacking
     on a dedicated Z80 system, I was testing code by blowing EPROMs and
     plugging them in the system, then seeing what happened. One time, I
     plugged one in backwards. I only discovered that after I realized
  that
     Intel didn't put power-on lights under the quartz windows on the tops
     of their EPROMs -- the die was glowing white-hot. Amazingly, the
  EPROM
     worked fine after I erased it, filled it full of zeros, then erased
  it
     again. For all I know, it's still in service. Of course, this is
     because the magic smoke didn't get let out." Compare the original
     phrasing of Murphy's Law.