 Hi, I'm Zor. Welcome to Indizor education. I would like to continue talking about electronic implementation of operations of mathematical logic and again, that's very important because it's used in all different computers, telephones, televisions, etc. Now last lecture was basically kind of a general lecture. I was talking about logical operations. Remember a few things from mathematical logic about true and false and operations of disjunction, conjunction, etc. Now this lecture will be about implementation only and implementation of only one operation, logical operation. It's a logical or or disjunction. And then the next lectures will be each one very short by the way about implementation of other logical operations. Now the implementation I'm I will be talking about is very sketchy. It's very I would say primitive. I mean, that's the beginning and again, that's my purpose to introduce you into the beginning of how all these thoughts about implementation of logical operations in electronics actually came about. I don't quite know who exactly was the first author of that particular model and there are other models. There are other implementations of the same ideas. But no matter what it is, it's definitely much more complex right now. But the idea is exactly the same and that's what I'm going to talk about today. This lecture is part of the course called Physics for Teens. It's implemented. It's presented on Unisor.com website. The website contains lectures, notes for each lecture, basically like a textbook broken into individual lectures and individual lessons if you wish. The website has a prerequisite course called Math for Teens and it's mandatory for learning physics to know mathematics quite well, including calculus, vector algebra, logic, like in this particular case. What else? Well, the site is totally free. There are no advertisement, no financial strings. You don't even have to look in if you don't want to. There are exams on the website and I do suggest you to take wherever they are available. So back to implementation of logical or disjunction. That's how it's called disjunction. First of all, again, let me remind you very briefly that the agreement among people who basically make all these devices which are using the mathematical logic is that the positive potential at one particular point indicates true or one and zero potential relative to the ground or relative to other, maybe, parts of the electronic schema is indicating false or zero. And right now we are talking about disjunction. So disjunction and that's basically I will use one and zero instead of true and false. It's just easier for me. So we are talking about zero vertical bar or arithmetic sign plus is used for disjunction. Should result in this, this should result in this, this should result in this and this should result in this. So these are rules of mathematical logic. So if, for instance, a true statement and a true statement, and now we're talking about statement like this or this, obviously if both of them are true, then both of this connected with an or sign will be true as well. Now if, for instance, one and zero, so one event is true and another event is false. And we are talking that's happened this or that. Well, yes, if one of them is true, then that's the result is obviously true. So in all cases where at least one of those components, this is the binary logical operation, when one of the arguments is true, then the result will be true. And only if both are false didn't happen event A and didn't happen event B. Now the question is whether A or B happened? Answer is no because neither of those happened. So this is the logic, this is the rules of disjunction. They came from logical operations from mathematics and they are used in decision making. Whenever we want to know actually what to do to go to left, to go to right, we have to make some kind of a decision and decision is based on logic. Now the schema which I suggested doesn't mean this is the only one, but this is one of the first ones which probably came to somebody's mind is which implements this electronically is the following. So you have two input contacts, call them A and B, and these contacts will have certain potential either positive which means the contact implements the idea of true or one and or zero neutral which means no excess or no deficiency of electrons at this contact and that represents false logical false or or zero. Now from these contacts we go to wires and we connect them to anodes of diodes. So these are diodes. Now you remember the diode is this is anode and this is cathode and this is heated. So we will put something like this some kind of a heat element. So cathode is heated and if there is there are some electrons here if there is no deficiency of electrons there is an electronic cloud because it's heated so electrons are just going out from the surface of the of the wire and if anode is positively charged these electrons will be attracted and there is a one directional movement of electrons from the hot cathode to cold positively charged anode and that's only in this direction because if anode is negative for instance and cathode is positive there is no electronic there is no electron cloud there is no thermionic emission as as it's called. So thermionic emission is only on the cathode which means electrons can go from cathode to atom and only in case anode is positive and cathode is negative or neutral not that way around. So the electric current goes only this way from hot cathode if it's at least neutral or even negatively charged too positively charged anode anode must be positively charged if it's if it's neutral there is no attraction and that's why electrons will just concentrate around the cathode even if there is a thermionic emission that will not go any further so this is the diode and this end is anode and this end is cathode now from this I will have a C contact these are my input input voltages if you wish and this is my output now what I have to do is I have to put some kind of a load resistance resistor and ground ground is neutral always it's a source of infinite number of electrons whenever we want it so let's just analyze what happens in each of these cases so this is my A and this is my B so ground is always neutral right so now in this case A and B both are neutral but the cathode is heated always that's true so there is some kind of electronic electrons cloud thermionic emission around the cathode however there is no difference in potential there is no positively charged anode here anode is zero which means neutral so electrons will not go there so they will just stay so whatever amount of electrons exist everywhere and initially we are assuming that everywhere there is a neutral nothing is basically charged in any way so this particular point and obviously output is also neutral well neutral means zero potential is neutral relatively to the ground it's connected to the ground but there is no current the electrons are not moving so there is this resistor which doesn't really play any kind of a resistance role there is no current electrons are not moving anywhere so zero and zero will give you zero so this actually is fine so this is C next case so this is one which means there is a positive charge and this is zero which means it's neutral now cathode is heated and there is an electrons cloud on the cathode there is a thermionic emission now this thing is positive right we're talking about this case it's true which means it's positive so electrons will move here from right to left in this particular case now what happens well there is a deficiency of electrons here developed right since electrons heat heated electrons from the electrons cloud goes this way and basically disappear because we are maintaining positive charge here right which means there is some some kind of a consumption of electrons on this side so this is always positively charged okay constant voltage let's say plus five plus five volt over them so electrons will go this way which means there will be deficiency of electrons in this wiring right well deficiency of electrons here neutral here so there is a difference in potential so electrons will go from ground to this sink and they will go and again they will be heated here well heat it here as well but from here it doesn't go anywhere because b is zero in this particular case it's neutral but in this case electrons will go so electrons will always flow this way which means that there is a current from here to here and considering this is a resistor there will be a difference in potential otherwise there is no there is no way so electrons from here go here and their deficiency of electrons will be still maintained all the time because no matter how many new electrons are coming from the ground to compensate this deficiency will immediately go out so obviously this point and this point and this and this so all this wiring will have deficiency of electrons because it will always go this way which means deficiency of electrons it's positively charged positively charged which means it's true or one in our logical lingo right great so this one is okay as well now this one is exactly similar there is no difference between a positively and b neutral or a neutral and b positively so we are not even talking about this it's very easy exactly the same logic electrons will go this way which means there is still deficiency of electrons here there is no movement here because even if there is a deficiency here there is no thermionic cloud on the anode so electrons will know but will not go this way so electrons will go from here from the ground to here and that means that that would be a deficiency of electrons here which means c will be positive and finally if both of them are positive so both anodes both anodes will be consuming electrons so the flow of electrons will be even greater and it exactly is it's exactly the same logic the deficiency of electrons here because there is a current here from neutral and there is a current so this should be less of a potential than zero which means it will be a deficiency of electrons because all of them will go this way deficiency of electrons is positive so that's why we have one here so this particular logic on a very simple level implements the logical operation of disjunction of logical or operation well basically that's it now as far as practical aspects now i'm explaining how anode is working on an old electronic vacuum tube technology doesn't matter right now it's a different technology it's semiconductors it's integrated scheme etc but the principle is exactly the same electrons are going from one end to another and not the other way around so this is basically the main principle of the diode as it it's implemented anywhere whether it's a vacuum tube or semiconductor or whatever so it's just simpler for me to explain it on the level of vacuum tubes because that's how it's all started and again my my idea is that to explain as everything started and the first coming to somebody's mind is better for general understanding because the details can be changed later on but the principle of implementation is more or less the same now what's the i would say deficiency of this particular implementation well think about this way if we are talking about positive as a constant voltage let's say plus five volt for instance then if this is positive five volts and this is negative there will be one kind of a current and we can work probably adjust this resistor so this will be also five volts but if both of them are then the current will be more intense and there is some mechanism which is not really here which is supposed to be adjust the voltage so it will be also five volts regardless if one or both are at five volts plus five volts right so there are certain deficiencies of of the of the implementation of this idea but idea is the same we obviously can think about what to do if this voltage is increasing and we can just reduce it somehow but these are details which i'm not going to go into this is for professionals whenever they are going into this for you i would like to really explain just the idea behind the logical implementation in electronics basically that's it you probably should be i do suggest you to read the notes for this lecture it's more or less exactly the same thing but again it's a description of how exactly electrons are flowing from one place to another in whatever case that's it thank you very much and good luck