In the old days electronic gear had on/off switches that were actually physical devices with two positions, like the light switch on a wall. Nowadays these have become a rare sight: with everything computerized, most state switching is done by pressing pushbuttons and keys, with the switching done by the logic circuitry or microprocessor.
The disadvantage of this solution is that (a) you can’t tell the state of a switch by looking at it, and (b) the act of switching can take a while as the computer goes about its activity. Even the basic act of turning a computer off now takes long moments (in the original home computers you hit the switch and power was simply cut off).
Here is a delightful exception to this trend: my latest Notebook, a Lenovo Thinkpad T61, has a slide switch on its outside for switching the Wireless radios on and off. Slide it to the right and the radio pops on instantly (as indicated by a green spot that becomes exposed under the slider). Slide to the left and the radio shuts down. Besides being fast and convenient, this is very useful when flying: if you believe in the inadvisability of having the Wireless on during flight, you can ensure it is off (and will stay off) before even turning the Notebook on. Absent this assertive hard switch, you’d need to turn the computer on, discover you left the radio on when you last put it into standby in the airport, and then you’d need to fumble with soft switches and dialogs to turn it off before the plane crashed. 🙂