[borgchick]

I've asked this question a number of times in interviews. Sadly, not one person has ever talked about debouncing. I think I would've instantly hired the person, if they talked about debouncing :P

To clarify, I would ask this question as a wrap up, a sort of final probe of depth test. If they don't go into much detail, no big deal. If they were good in the rest of the interview, they'd still get hired. If they were good elsewhere but also went into depth on this question, then it really boosts their likeliness of getting hired. I find that people who are curious about how things work, especially when it is outside of their main domain, are usually people interesting to work with.

[kamyarg]

can you link to a resource for reading about debouncing?

[kens]

The Art of Electronics has a good section on debouncing switches. There are various analog and digital ways of doing it, from R-C smoothing to latches to debounce ICs to microcontrollers.

If you want a thoroughly obsolete look at debouncing, I got a debouncing module from an IBM 705 computer (1954). This module was built from 8 vacuum tubes and a pile of resistors and other components. I powered it up with an inconvenient set of voltages (+140V, -60V, -130V) and actually got it to work: http://www.righto.com/2018/01/ibm-mainframe-tube-module-part...