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echo: classic_computer
to: JOHN RILEY
from: TONY LANGDON
date: 2020-05-14 14:01:00
subject: Re: HCF Halt and Catch Fi

-=> On 05-13-20 13:05, John Riley wrote to August Abolins <=-

 AA> instruction Halt and Catch Fire (HCF), the execution of which would
 AA> cause the computer's central processing unit to stop working (catch fire

 JR> Yep, specifically on the 6800 series CPU's.

I had heard that the originel Intel 4004 had a HCF instruction that effectively
shorted +5V to GND via the CPU, letting the magic smoke out. :)  It was a
design flaw, not an intentional "self destruct" instruction caused by the CPU's
logic gates being put into an inintended state, when a certain undocumented
(and unintended!) instruction was executed.

There are references to this on the Internet, but it's hard to tell how much
truth is in it.


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