magic smoke

electronics, humour A substance trapped inside integratedcircuit 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)