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Comment by gkhartman | Hacker News Reader

One of my favorite things in life is the the feeling I get when I open something up to find a pcb populated with dip switches (or jumpers) that are clearly labeled on the pcb. This practice has most likely disappeared to save pcb space, but it feels great when you don't have to grep config files or search for a long lost manual pdf.

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This would have backfired on one project I worked on. Near the end of the project I was asked to document the working of the DIP switches. I discovered that the settings were too complex, I couldn't document it in any way that would make sense to a user. But then I realized that they were being interpreted in software, and it was my software - I could make them do anything I wanted! So I wrote the documentation the way I thought made sense, then changed the software to match the documentation. If the switches had been labeled on the PCB it would have been too late for that.

That's an interesting situation that I hadn't really thought of, having only been on the user side of the switches. It seems like they would be painful to implement when adding them to a large project where software, hardware, and documentation may be handled by separate teams.

That was exactly the case here, I was asked for the switch description so the documentation folks could complete the user manual. It was just lucky that the switches weren't controlling the hardware directly.

On the other hand, whoever would have labelled them on the PCB could come to the same conclusion, right?

No, because I'm the one they would have been asking for the appropriate labels and they would have accepted them without question. There was a direct correlation between each switch and a board feature originally, so making up labels wouldn't have been hard. The problem was that the features interacted in a way that made it difficult to describe combinations that would deliver the desired outcome, and some combinations were flat out invalid.

It's a well-known way to create sensible interfaces. If it's hard to document, it is probably a bad idea!

I love it when there are three pins clearly labelled "UART" or "Console", and when you wire up to it, it gives you a "Welcome, Hacker!" style banner message and a text interface to do the configuration.

In the future, it would just use voice control. No need for any manuals or things printed on the PCB.

The only downsides are an always-on microphone and a few GB of voice models and recognition software. I think a switch is preferable.