Messages in this thread |  | | | Date | Thu, 28 Mar 2002 10:50:09 +0100 (CET) | | From | Jos Hulzink <> | | Subject | Offtopic: Re: DE and hot-swap disk caddies |
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On Thu, 28 Mar 2002, Alan Cox wrote:
> > Then there is this talking around about the "tristate of some" device. > > I'm really a bit sick of it. Becouse there is no such a state > > like a tri-state. We have just bus drivers on both ends. > > They are implemented usually as Schmidt triggers. They have three > > possible states on output: low voltage, high voltage, high resistance. > > Which is one, two, three states -> tri-state.
Eeks, a Linux developper who can count ;-)
> Electronics terminology then abuses that to mean the high impedance state (not > high resistance please if we are going to be picky).
Correct, though I hope in most cases the impedance is almost equal to the resistance, otherwise there would be problems at the current high speeds.
For those who don't know the difference:
Resistance is only a part of impedance. Inpedance also contains a frequency-dependant part, caused by induction in, and capacity between wires and electronic devices.
The idea in formula:
Induction = Resistance + frequency * Induction + 1 / (frequency * Capacity)
For an accurate formula, see any book about EE.
Jos
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