ON/OFF SYMBOLS

Why is there a vertical line inside of a broken circle? Or just a line or a circle? Does it really make sense to have a "|" and an "O"?

Turns out the "|" is really meant to be the number one and the "O" is the number zero. This is based on a binary system where the numbers all fall between 1 and 0 meaning that 1 is representative of power and 0 is representative of no -- or zero -- power. Makes sense? Well, some people assume that the "|" refers to an open circuit and "O" to a closed circuit; the latter because the ends are connected together and the former because the circuit is open at both ends.

In the image above the top left and bottom right photos are from personal computers and despite being a mac and PC, respectively, they share the same symbol. It makes sense to have the on and off symbols together since the button is dual-purpose. Yet it feels as though in order to have the symbols have equal weight, they should be overlapped and centered so that the "|" is vertically bisects the "O". But good design prevailed! It doesn't make total sense, but it looks more dynamic since it is not as flat as a centered vertically bisected symbol. Any electrician will tell you that the top left image's symbol is actually representative of on and not fully off; the symbol for true on/off would be a vertical line inside of, but not touching, the closed circle. Check out the VCR button's symbols. It is translated as "not fully on/off" and "on", which makes sense in that the clock of the VCR is on even when the VCR itself it off. It does look awfully cumbersome. At least the powersupply (top right) gets it right.