 Hi, I'm Zor. Welcome to Unisor Education. Let's continue talking about implementation of yet another logical operation in electronics. In this case operation is exclusive OR or XOR. Now it's sometimes called addition by modular 2 because the rules are like this. Now this is operation of XOR so zero and zero gives you zero and zero and one or one or zero gives you one and one plus XOR one. It's again it's equivalent to addition by modular 2 because one and one is two by modular 2 is zero. So that's what operation of XOR actually means. And here is implementation again it's a very primitive implementation but nevertheless it brings you to idea of this implementation. So how it's work, how it's working. So A and B are input voltages. C is output voltage and I would like to prove that these are implemented in this scheme. These are diodes where the triangle is it's an N node and where the straight line is a cathode. Let's again use the vacuum tube analogy or implementation of diodes. So the cathode is hot and the electrons are flowing from cathode to N node if N node is positive because it will attract the electrons which are in the thermionic cloud caused by the heat of the cathode. Cathode is a heated so it's a source of electrons in the cloud and if N node is positive there is a flow. So what happens is follow us. Well first let's just think about initial case when zero and zero are related. Okay if everything is a potential zero there is no difference in potential anywhere. So there is no movement of electrons and obviously this also will be at zero potential. If it's not then electrons will probably go this way or this way and it will neutralize eventually whatever happens it will be at zero. Okay fine now let's consider one of these cases. Let's say A is positive. Now what happens then is as follows. This is heated cathode. This is the positive. So the electrons will flow this way to the positive. Okay what happens next? Well next there is a deficiency of electrons here because electrons are moving this way. Now can it be compensated? Well think about it this way. If there is a deficiency here now these are connected with a resistor so from this point electrons will start moving this way. Now where this point takes its electrons well this is zero right this is one this is zero this is plus this is ground. So the ground is the source of electrons so in this particular case as soon as a couple of electrons are moving this way to compensate the deficiency here. The electrons which are in a cloud here will start moving towards this end to compensate the deficiency. So basically and where these electrons are coming from from the ground. So basically this is the direction. So the whole thing will be from here to here to here to here and to here from ground to plus electrons will move. Okay now if it's vice versa if A is deficiency of electrons which is positive and B or either way other way around. A is zero and B is. So whatever one of these cases they're completely symmetrical so I don't even want to just talk about to talk about this. And now the last one that's important what happens. So both of them are positive now if both of them are positive then the electrons from here will will there is no source of electrons that's what my point is. If there is no source of new electrons nothing is maintained on the ground there is no source of electrons. So there are no new electrons to move from one place to another to compensate this positive or compensate that positive because there is no there is no electrons deficiency here deficiency there. In the previous cases when B was at ground level the ground level means we have an unlimited source of electrons but in case both of them are positive there's a deficiency here and here electrons will not move basically anywhere. So there is maybe some very very minimal movement of electrons here but as soon as they're moving here there is nothing to compensate it so they will just stop moving basically. Okay so from here there is no movement because there is no new electrons coming from here so electrons will not move and everything stays where it is at zero potential here. Basically that's the idea. Now the real implementation is definitely more complex because it all depends on this resistor and the parameters of resistor parameters of diodes etc but it's an interesting engineering concept electronic engineering concept how to implement this purely mathematical logic in electronic schema. Okay that's it I do suggest you to read the notes for this lecture it's all presented as part of the physics 14 scores on Unizer.com and the comments are maybe a little bit more explanatory when I was writing them than what I was just trying to present verbally and the pictures definitely nicer. So I do recommend you to go to this website for additional explanation and basically that's it. Thank you very much and good luck.