Hacker News Reader

Comment by terr-dav | Hacker News Reader

>He's drawn one of those circle-in-a-slot switches. I often have trouble figuring out what the on / off state of those is supposed to be.

iOS has an option to display I/O labels on these toggles too, and as it turns out, not everyone knows that I/O refers to on/off. I found out about this when I had to explain to a friend that those symbols meant open and closed respectively on the vents in a car.

View on HN

I know what I/O refers to, and I have for the last, I dunno, 30 years. Do I know which letter refers to which state? Not a damn clue. I have never been able to remember it.

It’s not I/O (the “I” displays with serifs for me), it’s |/⭘ (line and circle). As a mnemonic, you can think of it as 1 and 0 (for on and off).

The standby symbol ⏻ combines the two.

And the 1 represents a connected circuit (power flows when on) and 0 represents a closed loop, no power flowing through, so off.

??? Electrically, a closed circuit is on, and an open circuit is off. No power can flow in an open circuit.

> As a mnemonic, you can think of it as 1 and 0 (for on and off).

I always thought that's literally what it represented, true (on) and false (off).

Yeah, terrible convention, especially because on and off both begin with O. And memory-aid stories don’t help: “those symbols meant open and closed respectively on the vents” - hang on - is O like an open vent or does it mean off?

Reply on news.ycombinator.com