Episode 168 - Halt and Catch Fire

Imagine a secret number that could be used to bring your computer to a screeching halt. In 1977 Gerry Wheeler discovered an interesting feature of Motorola's new 6800 microprocessor. There was a secret instruction that, if read, would cause the processor to stop working. He called this magic number Halt and Catch Fire, or HCF, and wrote a neat article about the operation. This was the first time the public would learn about the secret powers of HCF, but this isn't actually the beginning of the story. When it comes to HCF things are more complicated than that... but only a little bit!

You can listen to Episode 168 - Halt and Catch Fire online on Radio and Podcast. Open the player on this page to stream the available audio.

Episode 168 - Halt and Catch Fire is an episode from Advent of Computing by Sean S Haas.

This episode is 26:45 long.

This episode was published on Oct 19, 2025.

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