So, in the previous lecture, I had discussed about what is basically is meant by the switching system and I explicitly stated that it is the information switching about which we are going to discuss in the course and then I actually gave the history that how the manual telephony actually started. Manual telephony basically means the manual switches whereby the human operators were used for doing the switching function at the exchanges and we required those exchanges because we wanted to reduce the cost of laying the cables because we never wanted to have full mesh connectivity where every user is going to be connected to every other user. So, and then of course, there was all kind of a problem which were there with the manual system and I had discussed about the protocol or the complete sequence of procedure which was used to set up a call or tear down a call and how the call details were recorded in a register which was a paper register in the earlier days and then which was then later on used for to generate the bills by the companies. And then of course, I mentioned that a gentleman an inventor named A. B. Strauser actually came up with the idea of having an automatic exchange and was purely electromechanical it was using mechanical components basically rotary arms which will change the connection point they can connect to different outgoing ports from an incoming port and these were all essentially being controlled through electromagnets and using electromagnetic electrical pulses. So, these magnets the arm electromagnets will cause the arm to actually move the connection arm and this therefore, is changing the connection between input and output port. And I actually discussed about pictorially how a unisector and how a two motion selector will usually used to look like, but these are all old stuff now because I think none of the exchange all across the world are working on this thing except probably in some museum perhaps and, but you can still find pictures on the net. And then I had come up with I discussed the concept of cross point a cross point was invented because of the minterance issues which was involved in case of the electromechanical switches or Strauser exchanges and which is basically gears being worn out with time the connections are basically wherever the two contacts two points metallic points are coming into contact those getting weird out and there is dust oxidation all kind of issues because these are all exposed to air. So, ultimately people came up with an idea of having two metallic contacts which actually get either in touch with each other or they are separated in a glass bulb which is sealed glass container and having some inert gas that is basically the cross point then I also mentioned there is going to be a two electromagnets which are required. So, that you both of them are energized you will have the cross point snapped in cross point will have a connection you can actually work even with one, but with one you cannot build up a switch. So, let me start with having only one electromagnet doing this job. So, you will actually have a glass bulb and then there will be one cross point there will be another cross point this actually is one cross point, but they are two metallic contacts. So, I can actually push an electromagnet like this and whenever you are going to energize this at this point at this control input this will armature will actually move down and in turn the connection will be made. So, the input port will be connected to the output port. Now, if I build up this kind of thing and I want to create a cross bar basically a switch this is going to be slightly tricky it is not that easy. So, let me take up a four point and I want to connect it to say four outgoing ports and how I am going to create a switch. So, I require a point here. So, this is essentially a cross point I am showing it to a bulb and this is getting connected here. So, whenever this snapped in the connection will be made here. Now, I can create another bulb here another bulb here. Now, how these will be actually control that is usually the issue. So, similarly I can make four of these kind of the second branch and then connect them to only thing I have to ensure is that for any output line either this bulb or this bulb and they will be actually similarly there will be more bulbs here. So, only one of them have to be operated. So, there will be four lines only signal should come from only one of the incoming lines not any not more than one because then information cannot be separated out it will get mixed up actually. So, this technically is nothing but is a cross point this I mentioned in my earlier lecture also. So, this is one cross point this is equivalent to this is the next one which is equivalent this one third one which is this one and fourth and similarly this one corresponds to this this one corresponds to this and so on. So, all these cross points and which is obvious way I will require 16 cross points of this kind for connecting four inputs to four outputs and of course, as I mentioned I need not I need not only I need to only maintain about this upper half of the contacts because one will usually will never like to connect to one because this one and this one are connected to the same user actually and this two is connected to second user. So, you only technically require n into n minus 1 by 2. So, in this case this will turn out to be 6 4 into 3 by 2 which is 6. So, I have 6 cross point 1 2 3 4 5 and 6. Now, the problem is I need to have how many control lines to actually set up the connection because I will have some control circuitry because that is required additionally which will control each one of those cross points then I have to also have some some logic which I for example, maintaining that only one signal should come from to any output port. So, this output port for example, this one can get a signal from this input this input and this input. So, only one of these three should be activated. So, one in each column only one of the cross point should be activated not more than one that is one rule it is possible to activate more than one in a row. So, it is possible that I can activate this scenario this usually is known as multicasting a multicasting technically means from user one I can send it to a group of user the same information. So, one can send it to 2 3 4 5 it is not sending to 6 7 8 for example. So, this multicasting if it is sending it to everybody this is broadcasting. So, that is a different between difference between multicast and broadcast. So, only for multicast whenever multicast need to be implemented by a switch more than one will be activated cross points will be activated within a row. So, this actually means I require 6 actually control signals. So, there will be 6 wires going out from here and as you say this actually complexity is O n square. So, as my switch size increases I require larger and larger number of control wires being going out from the control from the controller unit. Now, how to actually handle this scenario can I make it better. So, if you remember in the earlier lecture actually I have drawn modified the picture there was a modified version this was not the one I had also something called an electromagnet sitting in here there were 2 control lines. So, one is a horizontal I call it other one we call it vertical control line when this is snapped in this actually there is a half way somewhere. So, you will end up in getting this is will be the new position when this electromagnet will get activated this will further move and you will get this position. So, then the snap will happen. So, unless you activate both horizontal and vertical the connection will not be made between the 2 points. So, cross point will only operate if both the electromagnets are operated with one it will not be. Now, how to solve this whole problem actually is an issue. Now, let me try to set up a certain connection if I do it this way. So, I am drawing a 4 by 4 cross bar. So, that technically means again I can actually have 4 lines, but that actually means for all the 16 cross points I require 16 to 32 actually control wires, but this is actually being doubled, but may be this is possible let me try it out. I can build up a control one control for the complete horizontal line and this is controlling all the electromagnets here. Then for the second row again I may have one single control line controlling all the electromagnets. So, this is the way actually this can be done and I can use similarly the vertical lines for controlling the vertical component of the electromagnet. So, number of control wires are required are here is 4 into 2 which is 8 which is o n the complexity is linear here it is not n square. Now, can we actually work with this kind of situation. So, if for example, I want to set up a connection between say 1 2 2 prime 2 2 3 prime. So, may be probably let me check if I can make all connections or not. So, and remember these are not symmetric usually whenever you make connection from 1 2 2 the other side of connection will be from 2 2 1 because the voice is always bidirectional and I am assuming this connection to be unidirectional, but I am actually taking it as generalized which I am not putting the symmetry conditions which are usually true for most of the voice circuits. So, voice circuit is always set up in both the directions. So, that when any one of the two users are talking other person can listen to it. So, it is actually a bidirectional communication between two end points. So, if I want to set up 1 2 2 what I will do is I will excite. So, I am going to actually put a take here I will excite 2 and I will excite 1. So, this will snap in and this connection will be done. I want to set up 2 and 3. So, I will excite 2 here and a 3 here and this will snap in, but there is going to be a problem here. So, the problem here it will be when I am going to excite 2. So, this will also excite this thing because column is already excited and whenever I am going to excite 3 this is also going to get excited. Now, this is a complication. So, maybe we need to put up some other rule. So, what we will do is for any cross point. So, I am going to have two control wires, but I can put up a logic circuit. This will then create I am now going to create a logic circuit here in between and one of them will be creating a controlling horizontal line other one will be controlling a vertical line of the cross point. Now, this logic circuit will ensure that if the horizontal line is done activated first and vertical line activated second then only h and v both will be activated on the outgoing line. If only h if v is done first and h is done later on then this will not be activated. So, this will got the activation this will not cause the activation. So, once you do this what will happen to the same switch. So, let me see what is going to happen. So, if 1, 2 connection I am going to set up. So, 1 is this I am now doing horizontal first and 2 I will do second. So, horizontal vertical the connection should snap in. So, connection will snap in this will work 2 and 3 if I do 2 here 2 being activated. So, this line gets activated and then what I will find is the here the vertical this 2 was activated first. So, this cannot be activated actually. So, this particular connection will not snap in only this will snap in. But, when I am going to do go for 3 when I will activate 3 now for this particular connection I will find that now the condition h v because 1 has been activated first and 3 has been later. So, this connection as well as this connection will snap in. So, from 4 I am able to reduce it to 3. So, I have to do further innovation if I want this thing to actually work otherwise this system will not work. So, I need to modify the logic circuit and may be what I can do is one of the options is I actually activate a horizontal line first then vertical line first then you put down the horizontal line connection will remain connection will set up and horizontal and vertical both are up and once you put horizontal line down connection will be maintained and when the vertical line will be now put down then the connection will be closed. So, this is the period when the connection will snap in. So, I can use this particular logic and this can be programmed in this logic circuit actually. So, once you do this let me see what is going to happen. So, when 1 is going to go up which is horizontal 2 is going to go up and then of course is like 1 is going up 2 is going up 2 prime and then 1 is going down. So, once this happens this connection will snap in now when you are going to activate 2 after this. So, there has to be all these lines are they are active and now only depending on which line I am going to now go will go up it will depend on that. Now, I am going to actually put 3 prime will go up, but 1 is already down. So, 1 up and 3 up condition will not happen. So, 1 up and 3 up condition does not happen. So, this will not snap in this will not snap in only this particular part will snap in when 2 3 will happen okay. The other condition is for this 2 prime is up, but 2 prime is not going up after 2 this 2 is going up later than 2 prime. So, this cannot this connection also cannot snap in only these 2 connection will snap in and they will remain till the time 1 and till the time 2 prime or 3 prime which are up. So, these will actually control the connections okay. So, from any other input you will not be able to set up the connection to these outgoing ports. So, only 1 of these columns can remain active at any point of time only thing which you have to ensure is you should never do 1 1 up you should never do than 2 up and then if you are going to do 2 prime up then there is a problem actually. So, if you do 1 up and 2 up and then 2 prime up even if you then actually let down 1 you go down to in this case these both these particular points and these point both of them will remain snapped in because that is what they will be happening at this point. So, every cross point will be snapped 1 at a time that is a condition if you maintain this algorithm can work very well to set up the connection in case of a cross bar matrix and you require only 4 horizontal control line and 4 vertical control lines and complexity is going to be O n as far as the control lines are concerned. Only thing is that with every cross point you require some additional logic circuit which is nothing but technically a commutative logic circuit is a sorry is a sequential logic circuit and this can be built using some flip flop and other things. So, I think all fundamentals of basic electronics this electronics can be used here to build up the system. So, that is how the cross bar used to actually work, but so far what I have done actually very smartly what I have done is I have always said horizontal goes up vertical goes up and horizontal goes down and the connection remains on when vertical goes down the connection is closed. You should ask a question why it cannot happen this way that vertical goes up horizontal goes up vertical goes down connection remains and when horizontal goes down connection gets closed. Let us see what will happen if I am going to use this particular strategy I am going to take same 4 by 4 same connection sequence and let us see if I can do that I can handle this connection. So, I am going to now do the vertical thing first. So, my connection set up pattern is 1 2 2 prime and 2 2 3 prime. So, that is a pair which I am trying to set up. So, 1 2 2 prime if I want to set up as per rule that I have to activate 2 first. So, if I do activation of 2 first 2 prime goes up 1 goes up 2 prime goes down connection should remain on till 1 goes down. Now, at this point I am going to now put when this connection is up that time let me try out 3 prime goes up 2 goes up 3 prime goes down the next connection set up. Let us see what happens in this scenario. So, when 2 is going 2 prime is going to be activated 2 prime gets activated 1 prime will remain activated at this point of time in this row. So, this is control lines. So, you will do 2 prime first as you can observe from here and then 1. So, this connection will snap in and this 1 line is now active this is active at this point of time 2 prime then goes down when 3 prime goes up and. So, this and this all thing get activated, but 3 prime has not been activated first. So, this line will have nothing to do this will not get activated and once 3 prime is not activated 3 prime is activated 1 prime has 1 has not been activated first it has to be activated later on if this point has cross point has to be activated when now you will excite 2. So, this point will snap in nothing else can actually snap in this line is not active only 1 is active here now 2 is got activated 3 prime you will put down and this line will remain on hold. So, both these connections will work. So, this actually does work there is no issues in this case, but only problem in this case is you cannot implement a multicast thing suppose I want to set up 1 to 2 prime and 1 to 3 prime kind of scenario I want to set up both these connections now let us see whether this is possible or not possible. So, in this case I need to activate remember I need to activate vertical first. So, I will activate 2 prime I have to activate 3 prime I have to activate 1 prime and then of course 2 and 3 will be activated first when 1 prime is activated these both will snap in let me show it with a different color and then 2 prime can go down 3 prime can go down and so far 1 is there being on hold the connection will both of these will remain snapped in, but these both have to be done simultaneously. Now, if I am going to use horizontal vertical horizontal then what will happen the same scenario I have to now activate 1 first 2 prime 3 prime and do a control. So, both of them will snap in and then 2 and the 1 has to go down and then these 2 points will remain snapped in till the 2 vertical lines which are going to be there you need to actually hold on to 2 vertical lines which are there. So, I think these both of these systems actually do work without any problem except in certain scenarios, but usually what is preferred is this horizontal vertical horizontal and the output line is what is going to be used for controlling in because once you have snapped the connection you are not going to set up any connection to the vertical line. Now remember in this scenario of multicast which I had actually used earlier where vertical has been used first I have been setting both multicast simultaneously suppose the first point has been already set up wherever I have done 2 I have done 1 and 2 prime has been gone down connection is up and now I want to set up from 1 to 3 also another multicast connection now that will not be feasible in this scenario, but that will be feasible if I am going to use this particular case. So, usually most of the implementations were actually have been built with this kind of thing of course the way to handle this particular situation is if you are using lower kind of control system is that if you want to set up if you have already set up from 1 to 2 prime already a connection and now you want to also set up 1 to 3 prime when this connection is active you dismantle both the connections and now do a setup simultaneously. So, you have to break up an earlier connection that was the only way this could have been done here while in the second case or with the first this particular control strategy this can be done without any issues without breaking the earlier connection. So, this was a most popular variant which was actually used. So, this is how the cross point or cross bars usually used to work and this forms the basic unit of the switch. So, usually the switches are defined in this way there is a input port there is output port and important property of this particular switches it is strictly non-blocking. Now, I have to actually now define these terms because in the whole this lecture series you will be actually listening to these terms very frequently. So, before going on further so we define something called strictly non-blocking that is the first thing. So, meaning of this is if you are having an input port which is free if you are having an output port which is free irrespective of whatever other connections which have been set up between other input output pairs I will be able to always set up a connection or a path between this free input port and free output port without disturbing any other connection. So, a formal definition will come once we will define a clause theorem which is forestry blocking thing is basically says that if there is a set of free inputs here and set of free outputs here. So, it is talking terms of set. So, there is a I prime if I is the total number total set which is there total number of inputs O is the output. So, O prime is free outputs I prime is free inputs. So, I prime is a subset of I O prime is going to be subset of O. So, I should be able to create a legitimate multicast tree from any input which belongs to I prime to any subset of O prime any subset of O prime. So, there is a legitimate multicast tree which can be created. So, that is a most general definition of strictly non-blocking and this has to be done without disturbing any existing connections that is what the strictly non-blocking means. Now, second variety of a kind of switch of property which is known as rearrangeably non-blocking. So, this says actually the same thing can be done, but the condition that I will not disturb the existing connections cannot be maintained. So, existing connections might have to be disturbed, but we will make set up the same connection they will be broken for some time then I will again set up the connections and once a new connection is set up the input to output mapping will still be maintained same only there will be disturbances which will happen. So, I might I might be rearranging the structure in between and then this become rearrangeably non-blocking. So, in that sense if you see when I was looking at this particular case if I you are going to use a strategy of V H V V up H up V down to set up a connection this is actually a rearrangeably non-blocking switch because I am going to disconnect and then connect for such kind for creating certain multicast trees actually. If from one input you are connected to one output connection is already on functional and then you want to create the same input to another output free output then you have to disturb the earlier connection and then you have to connect again. So, in that sense yes it is a rearrangeably non-blocking. So, usually whenever I am going to use a block I am going to use call it cross bar I am actually assuming that I am going to use a strategy of horizontal control line first sorry horizontal control line first vertical then and then horizontal down then connection is set up till the vertical is also pulls down actually. So, that means we will be making them strictly non-blocking. So, rearrangeably non-blocking also I think now is clear we have to do the rearrangements, but any legitimate multicast tree between input and output pairs can always be created, but it requires disturbance of existing connections, but existing connection mapping from input to output will be still can be made, but connection will be broken for some time, but not necessary all the time, but some of time it will be done it cannot be guaranteed initially non-blocking it will be guaranteed. Now, third thing which is going to be blocking probability blocking switches. So, blocking switches means there is input is free output is free, but as something is not there in between the switch it is not possible to set up the path in cross bar of course you would not see this, but cross bars we do not use I will come to the reason why we do not want to use this, because cross point complexity here is O n square and of course next question comes is can I make up a switch which is strictly non-blocking like the cross bar and still have a cross point complexity less than O n square. So, I will give an hint later on we will actually prove through closed theorem yes it is actually thus possible. So, blocking switch are those switches where even if input and output is free sometimes you will not be able to set up the connection and of course the fourth category is wide sense non-blocking. So, we will see an example of this kind of switch also and you will formally prove that yes this is done through actually building up what we call state diagrams and state transition diagram and saying figuring out that if I can avoid certain state this switch will always remain non-blocking switch. So, what happens is basically the meaning is if while setting up the connection I follow certain algorithm and that algorithm is well defined and which ensures that I do not get into blocking states I always the avoid the blocking state I will set up all possible connection patterns between free input and output ports this usually happens because free input and output port they can be connected together in more than one possible ways you have to choose judiciously only those ways by which switch will always goes into a state which will always a non-blocking state it does not create a blocking structure. So, those kind of switching structures are wide sense non-blocking switches we will also see as an example of this kind of thing. Now, I have built up this switch across bar which is O n square complexity number of cross points which are required are n c 2 if it is only a upper half triangle of the full square then it is going to be O n square and it is strictly non-blocking switch. So, theoretically now the question is can I actually have something better than this or not yes it is possible to build up something better a class network provide O n 3 by 2 O n to power 1.5 is the complexity which will come. So, anyway I am not going into that as of now the only way that O n square now can be further reduced how that class network comes I am now coming to that thing that if I build up only one switch which is strictly non-blocking may be it may not work. So, idea is can I actually create n of course, if n becomes large say 10,000 or 20,000 say 1 lakh or 1 million or 1 crore how you will are going to set up a switch. So, in fact here also one should understand the concept of network. So, what you do is you never use a very large size switch as such you then will start always going to use multiple smaller switches and then create interconnection between them. So, you can actually put multiple switches like this and create subscriber to that. So, these are subscribers attached and I can create an interconnection between these switches. So, this what forms the network. So, all these switching matrices can be there in one building or they can be distributed all across the country all across the globe and that what forms that actually network.  So, internal network is usually not visible to the subscriber. So, in fact network is technically is nothing but single gigantic distributed switch which is built in redundancy mechanism and built in maintenance mechanism. So, part of it can fail, but the remaining part will always work even if some part fails your connections can be routed from other routes. So, the larger distributed structures are going to be random usually it will be a mesh, but what we can do is we can within a small dimension for within a building if I want to create or within an organization I want a larger dimension switch. Maybe it is a good idea that I can take a smaller switching elements switching crossbars and then join them in certain structured fashion to create a bigger gigantic switch. And that is a regular connection pattern we call it a switching network. So, next step is then that we have to see that how this switching structure is going to be built. So, now these using small switching elements or switching matrices I need to create a larger switch that is basically is the problem first and I need to retain certain properties. So, I think natural thing is that I would like to create a very similar property like we have with the crossbar strictly non-blocking property and it will create a larger switch using smaller crossbars. So, let us see if that can actually be done or not done. So, maybe common sense will tell I can going to get a crossbar some values n by n and I can use multiple of them and I am going to try with regular structure how this will be done. So, simple idea is that there will be n input and there are 1 to k. So, now total size which is going to be available is n into k. Now, but if I actually make this some input here cannot be connected to this output there is no path between them. So, I need to do something and secondly I also want is the path length from here to here input to output has to be exactly same almost. So, 1 possible ways I can now because I want n k inputs and n k outputs or let me also have similarly the other crossbars. So, which also have n outputs and they are k such things which are there. So, there is 1 stage 1 which is input stage 2 which is output and I want to create a connection between them. So, that everybody can talk to everybody else, but I want to keep them strictly non-blocking that is basically is the idea. So, this is a kind of a switching network which we are going to create, but it is a structured entity. Now, each of this input in this particular switch should be able to connect to any one of the outgoing port which usually is the condition. So, what I can do is I have I can create it as n by n. So, there are n outputs and there n such switches. So, I can just distribute them. So, 1 wire going to each one of them. So, I can do same thing here. So, perfect I have done this and then all free ports either are used as input port and output port.  So, we can actually observe if somebody has already set up a connection from here to here this path is busy. This switch per say the element itself is strictly non-blocking, but this path gets occupied next free input port and next free outgoing port they can they connection between them cannot be made because this path is not available this path is already occupied. So, this makes it a blocking switch. So, may be an idea can be instead of using n by n here can I use n by 2 n. So, let there be 2 n lines. So, I can put 2 lines all the way coming to everybody I can do it. Now, this is a different kind of cross bar cross bar earlier time I have told you was only having 4 incoming and 4 outgoing. So, I can actually have now 8 outgoing and 4 incoming. So, I can put that cross bar now I can set up 2 connections, but when I try setting up third connection. So, it is not possible actually. So, ultimately what you will do is if I want all n connection want to go to this n connection I require how many lines here actually that is very important. So, in worst case if all these ports are connecting to all these outgoing ports on switch 1 from switch k I require here n connections. So, you will be building up n n square here because you require n for this n for the next switch n for this n square outputs. So, you will end up in n into n square switch n you require 2 k such switches. So, number of cross points will be required is n cube 2 k now the whole thing can be equivalently represented by a switch of n k by n k. So, which will have a complexity of o n square k square in this case my switch complexity is 2 n cube k and of course, if it turns out to be that n is equal to k both of them are going to be technically same and both will be strictly non blocking switches. So, even with 2 stage actually it is not possible because there is no other way you can make the interconnection and this is only way you can build up a strictly non blocking switch. So, complexity is going to remain same it does not change. So, because if you put k is equal to n this will turn out to be o of n k square here also it is o n k whole square. So, maybe you have to go to a still better mechanism. So, let us see how this actually can be done. So, maybe with 2 stage this is not possible, but third stage is certainly is possible and that is where the cross network actually does come in. So, idea is this that I will have a switch I will have multiple of them and then I can create many such switches. Now, this switch can route the calls in this way there is exactly one path to each one of the switches and I can connect similarly this thing to each one of them and so on. So, idea is that you will actually have m 1 by there will be I will define actually m 1 by n 1 switch here k 1 of them k 2 switches and k 3 switches. So, because there are n 1 outputs. So, k 2 should be equal to n 1 that is how you can give no input port or no output port here should be left free only input ports are free here and output ports are free only here. So, that is a condition n of course total number of input ports will be m 1 into k 1 these are the number of incoming ports outgoing ports are n 3 into k 3. So, this switches are m 2 by n 2 these switches are m 3 by n 3 and since we are talking about symmetric switches these both terms m 1 into k 1 should be equal to n 3 into k 3. So, these switches should be same and you can see that k 2 has to be equal to n 1. So, that each one of these output port is connected to one switch in next stage similarly you can see that m 2 should be equal to the number of incoming ports has to be equal because one line is coming from each one of them. So, k 1 is equal to m 2 similarly should be equal to n 2 should be equal to k 3 and of course, k 2 is equal to n 1 is equal to m 3. So, this condition should be satisfied. So, this kind of structure known as class network and of course, intuitively or we will actually formally prove it this switch will be non-blocking if I am taking a case where m 1 is equal to n 3 it is all symmetric thing and when m 1 is equal to n 3 and k 1 is equal to k 3. So, that case when you will have k 2 greater than or equal to 2 into m 1 minus 1. If this condition is satisfied this switch will be strictly non-blocking switch. The logic is pretty simple that there is a free input port here which I want to connect I will show it with a different color. There is a free input port here which want to get connected to this one. So, remember there are only these many links which are there which will be nothing but. So, if number all output ports are occupied except this one which I want to connect you already have because I have not taken m 1 is equal to n 3. So, m 1 minus 1 these links are occupied similarly on this side also m 1 minus 1 links are occupied in worst case these might be choosing a set of nodes here these might be choosing another set of nodes here and there is no overlap between them. So, I need only one more extra which can be used to set up this particular free path to this and this will always guarantee that in worst case I am able to set up the path it becomes strictly non-blocking that is basically is the philosophy which will actually means m 1 minus 1 plus m 1 minus 1 plus 1 k 2 has to be greater than or equal to that that will give me the strictly non-blocking condition. This is also what is the class theorem technically is in fact there is a generalized form for that it says that k 2 has to be greater than or equal to m 1 plus n 3 minus 1 actually. So, this is a more refined form. So, I have taken it as taken a very simplified version of the same thing now with this if you can actually compute the cross point complexity. So, here I am actually now finishing and I think I urge all of you to try to make an estimate of what is going to be the cross point complexity for this configuration. This is known as cross network configuration and then you will actually figure out and appreciate yet this yes this is going to be have a smaller complexity than a cross bar and I am still able to create a strictly non-blocking switch. So, we will continue with the same thing this particular thing onward in the next lecture.


After Bakhmut, the next area in terms of battle intensity is Lyman Kupyansk. Unprecedented bloody battles are currently taking place directly in the urban area of Bakhmut. Serhii Cherovati, the spokesperson for the Eastern Task Force of the Armed Forces of Ukraine, has said, directly in the urban area of Bakhmut, bloody battles unprecedented in recent decades are taking place. The enemy has set the goal of taking this impregnable fortress Our soldiers in bloody fierce battles are doing everything to wear down the enemy's combat capability and knock out its strength and morale. And every day, they are successfully doing this in each corner of the city, trying to inflict maximum damage on the enemy. Cherovati said, This area is the leader in the shelling. During April 14, the enemy fired 307 times at our positions there, using various calibres and fire systems. Several clashes occurred there, 12 invaders were killed and 44 were wounded. Their newest T-90 tank and infantry fighting vehicles, as well as an artillery tractor, were also destroyed there during the same day. Bakhmut has become a point of infamy for the Russian troops, Cherovati said, With such huge efforts not to take the district center within nine months, this is a shame that they will never be able to wash off.


Life on this planet can be hard and when you're faced with the pressure of figuring out what to do with the rest of your life It's enough to make you feel like you're going to explode But don't eat yourself out the window just yet Today we're gonna help you figure out how to choose a university Hello, my people today on the score channel I'm gonna be showing you guys a little bit about how we approach the problem of Choosing a university and hopefully take some of the pressure off of you guys so that you don't feel like this is the most important Decision in your life because spoiler alert. It's not There are four key questions that you should consider where how What and when now the order you consider those questions also matters Most people start with the what but I want you to start with where I'm talking about where as in Where on this planet do you want to be for the next several years? Do you want to stay close to home close to your family or do you want to get as far away from them as humanly possible? Do you want to stay in-state or go out of state? Do you want to stay in your country or go to a completely different part of the world? Where you go dictates some of the things you can do So you should think about the kinds of activities that you like to enjoy if you would rather be doing cold weather sports Then get up into those mountains and go skiing if you'd rather be on the beach surfing it up then check out universities in LA Do you want to experience the hustle and bustle of city life or would you rather have a calm peaceful? Suburban environment all of those questions belong to the where category and we haven't even started thinking about universities yet And that's why it's so important the new year is a great time for setting goals and making plans One of the best ways to actually reach your goals is to use a technique called visualization You need to visualize yourself in that situation where you want to be imagine the sights and sounds that you'll hear Let's try it with New York Come with me on a journey The more you do this the easier it'll be for you to capture that image again and stay focused on achieving your goal This applies to everything not just universities using this technique all the time Once you've settled on a where the rest becomes a lot easier Let's move on to the how now how really just refers to how are you going to get into these universities? And it can be broken down into two aspects. There's the academic side, and there's the financial side How are you going to pay for it? How are you going to qualify for the university? The thing is this is easy now because if you've made it your goal to study in New York City and not necessarily New York University you have a whole range of options to choose from you can find a university That's perfect for your abilities and your budget You can figure out exactly what you need at different levels, and you'll get there no matter what with where and how out of the way It's time to ask when now Most of us think to do this as soon as possible, right? We graduate high school We go straight to university, but maybe that's not the best choice for you Have you considered waiting a year getting some work experience? Saving up some money so that you don't have to get into as much debt or take a year off and travel Learn a little bit more about yourself and spend some time on your own Or maybe you want to take a year off just to work on your English skills and beef up your SAT scores In which case you should check out prepwithscore.com. I left what for last intentionally I realized that's a controversial decision and a lot of people might think that that's where you need to start You need to think about what you want to study and what you're going to do with the rest of your life Listen up my people. This is not how it works. I Studied education, but I'm here making a YouTube video for you So I'm living proof and I got plenty of other friends who studied one thing and ended up doing something completely different I have one friend who studied film production, and he's an English teacher of another who studied medicine And he's a programmer What you study does not determine what you're going to do for the rest of your life So stop thinking about it that way What you study is simply a combination of knowledge and skills that will allow you to do other things with your life Now obviously if you have a clear idea of what you want to study go for it. Go do that But if you don't It's not that big of a deal and here's why First of all if you study you're probably going to have to do some general electives anyway A good example right here at the College of Engineering and the University of Michigan requires students to complete 16 credits of what they call intellectual breadth coursework General electives things that are not related to engineering. They give you a full list So even if you want to be a nuclear engineer You're still gonna have to take 12 credits of other classes and most people do that in their first year of study so You can go into the university and maybe in that first year You're not quite sure what you want to do so you get some of those general electives out of the way and maybe along the way You discover that your passion is actually something else besides that Universities aren't exactly teaching you all the skills that you need to get into the working world anyway Take a look at this a UNESCO paper talked about a study by the Pew Research Center Which is one of the best in the United States and it mentioned that even though 74% of the people surveyed found that university helped them grow intellectually only 55% saw their education as useful in preparing them for their job or career take a look at what Employers are looking for in the same paper. It talks about how the world needs leaders and employees with foresight Who can identify new opportunities design creative solutions and bring them to market? You see that word created is everything Creativity is when we'd make new ideas by combining existing concepts that we're familiar with What you study is going to give you some more ideas that you can combine together to make new creative things So now that we've covered the score approach, how do you put it into practice? What do you do? Well, the first thing you want to do is use the where so figure out where you would like to study Make a list of all the locations that you're interested in and then go find all the universities in those locations Don't just focus on your top schools or your favorites or the ones you've heard about Dig deep and look for every school that you can possibly find that sits in the area where you would like to be In the last episode I talked about why college rankings were broken But there is a good website that you can use to get an idea of how much you can expect to spend in University and how much that education is actually valuable to you It's called pay scale and here they show the total four-year cost of universities Alongside the 20-year return on investment in other words They take the earnings of graduates over 20 years and look at how that relates to the cost of the university Next start making a list of these schools according to your ability to get into them think about the how I Recommend making four different tiers the top one being out of reach These are ones that you just don't think you're ever gonna qualify for or simply could never afford The next tier is gonna be the dream schools These are the ones that you could possibly get into but you might need a scholarship for or maybe they're very competitive Even if you have the money next go with your best fit schools These are the ones that you could definitely pay for and that you definitely think you could get into and you Definitely think they would be right for you Lastly make a list of safety schools These are the ones that you know for sure you're gonna get into and they'll probably even help pay for it because you're so awesome But you'd rather get into some of those best fit schools or maybe even a dream school before you go here With those four out of the way you can start making your list of requirements such as your supplemental essays and Really get to work on your applications So guys the whole point of the video today was to talk about a different approach to how you can figure out which Universities you should study in and I wanted to share this with you because this is what we do here at score This is our whole game We want to help people find universities that are right for them and not just go to the best Universities or the top ten for this particular career We want to help people find places where they fit and we'll actually learn If you'd like to learn more about what we do then go to prepwithscore.com and see our services and see how We can help you figure out the university of your dreams This is just a little sample of the kind of work we do we work individually with each person to figure out exactly where they Want to be and what they want to do and how they're gonna get there and by working together We've accomplished some really great results already this year So if you're interested check out the link in the description if you found this useful Please like and subscribe we got more content coming out for you and let us know in the comments What you want us to make for you already some people are asking about different countries for us to cover So we're gonna be putting up some new videos on that soon as well as covering some other common questions that people have about the Application process. I'll see you next time


Should Spotify pay a higher percentage of its revenues out? So I said at the start they only pay 65% and obviously they keep the 35% back to keep the business afloat and keep it going and growing whereas you've got sites like Bandcamp that pay 90% of the money out. So should Spotify increase the system or like 70% or 80% or higher and this will be 60? 65%. 65? Yeah. This is when we get into the debate about whether we get angry when they invest 100 million dollars into the Joe Rogan podcast deal because obviously they keep them back the money to make these deals. So that's obviously in their best interest though to grow and expand so it's on one side should they increase revenue on the other side they've got to run their business. And think about it. It's also showing you the value of your content it does that so much so for creators in terms of podcasting but it even gives you an idea even with the music the value of your content. No there's no single artist that's been paid 100 million dollar deal I get it but if you look at it 60% right or 65% if someone says hey you know we'll give you 65% of the deal that doesn't sound that bad right. It's not that violating but when it gets cut through all these other pieces then you end up with what you end up with. Exactly. So in some senses I'm sure the licensing deal that these labels have are little Joe Roganish right. We just never think about what are the labels getting in mass as a whole because Joe Rogan's deal is a to some extent not fully right but it's a licensing deal I'll say that it is a licensing deal I was going to say music licensing deal but because it's a licensing deal it does have some similarities so when you consider that part all right what does it really look like okay you're popping like this and you I think it's three years right 100 million for the licensing and you still own it that's the biggest difference between Joe Rogan right and the artist right yeah he still owns it so he can have control of it license it and then at the end of the day if he wants to pop and keep moving he can he can do that but just the fact that he's the one in control of the creative to a fuller extent changes the game versus artists who sign to this whole system where really the system is speaking for you and then the other situation is artists who might own all their stuff but the the leaders of your industry as a whole are still running through that same middleman which is the labels it's meaningful when the leader right because the leader sets the tone and Joe Rogan if Joe Rogan was signed some other type of entity and kind of ran through a record label-ish type system himself then that also would have diluted instead of lower bar for how the other content creators but since he wasn't on that now you you get to see a fuller vision and version of what that's worth exactly is this kind of this is why I want to talk about this topic really because the obviously the debate is sort of feels like is the people versus Spotify but I'm not trying to defend Spotify here but I'm trying to be like objective but it's not all their fault everyone's got a part to play and they're not in control they're not the gatekeepers the labels keep Spotify afloat they're not in control in this situation therefore it's not just them who should be getting attacked and that's what we're trying to do in this sort of discussion when I was trying to highlight that and it's the same when you talk about the Joe Rogan deal we know he's in control Spotify are in his hands he can pull out when he likes they've got no control over what he talks about they're obviously here to facilitate and move into the next level in terms of audience reach which is why the labels wrong spot five because they know they can get a lot of value from it yeah and which is why Spotify is like F this music stuff I want to go into this podcasting thing because Joe Rogan setting the tone and he's legitimizing the platform even more so for podcast but everybody's deal doesn't look like his and I'm not talking about payout I'm talking about ownership they they bought the ringer I believe as a whole which is I don't know if you know that podcast but us do bill Spence Simmons very credible and and adult podcast and they're buying a lot of this other stuff our right whether they're rule they're owning so it's cool okay yeah we the worth of that right the trickle down effect of even just licensing and having that exclusively even if we don't own it to trickle down to this other stuff that we actually own it is it's you know five billion dollars worth right how much the stock went up yeah exactly like that it's a it's a beautiful thing for them as a company and that puts them in a position where now you don't have this variable cost of whatever the licensing and what am I paying this month you have a fixed cost because I own it and whatever costs to run this shit and any profit on top of that whatever that looks like which I'm more interested in digging more into what they do they just the sponsorships that they're taking from or what but whatever the profit is you know margins only grow right with the cost being fixed yeah no see the funny thing is as well that a couple years ago Joe Rogan was asked about why is the podcast not spot by and he's like you know Tommy's like we don't need to be like I don't care about Spotify and now here we are and he signed a deal to show you how you know the money talks on the business side of things like wasn't in his best interest back then to be on Spotify didn't need to be but now he's got the capital behind him raise okay I'll consider you now as an option he was on Apple before I think he was I think he's an independent else he had a good relationship with Apple he's one of the top podcast on Apple but he he was just asked why you're not on there and he was like it's not relevant for us right now I didn't realize that he wasn't on it especially even like if he wasn't seriously on Apple because that's even more so about your worth right if he was on Spotify already he wouldn't have been able to get the deal that he got it's particularly particularly not to that extent one you're already on there so you know so you know we don't have to convince you to come over we don't necessarily have to talk exclusive to we also are gonna be valuing you less on the brand appreciation in that uh what's the word good it's good something what is based on brand I can't remember what it's called good will I believe the good will of your brand it's just based on the numbers because we already see what your numbers do on our platform right yeah exactly there's that additional aspect of okay taking people from other platforms we make it exclusive but that that changes the negotiation completely so the fact that he wasn't on there and in a sense held out whether it was all strategic or not there was a huge benefit to that deal and how it happened I know people who are like that with tiktok because tiktok was trying to get people to come over right just like so many of these platforms do these days yeah and I don't want to get on yet because I want to go do their system versus just being on there and then they see how operate let me get money to get on to the platform so yeah that's uh well I did not realize or think about the fact that he wasn't on on Spotify but that part should be noted for anybody who probably think let me go start a Spotify podcast and then get bought up by Spotify right I think it's a little different it's a little different because a lot of his viewership is actually on YouTube that's where a lot of the views came from because the video formats on there so he was still when he was still yeah exactly so that was his he's in control of that he obviously he was on Apple podcast he was the number one downloaded podcast last year above New York Times daily but he wasn't actually with Apple like exclusively so it just just shows you that and now and I'll see at the time I didn't care about Spotify because he was doing well on his own but now he's seen the potentials like okay I'm getting a lot of money here and they can take us even further now in terms of like our reach yeah he's also seen the long-term strategy behind it now but at the time it wasn't really relevant to him so and still owns it man yeah I'm sure there's bonus incentives attached to things and like all type of performance and back-end things that the deal I would not be surprised if the deal was at least 200 million plus after all my money is is allocated but I don't you know I don't know you should certainly shake up the industry now in the podcasting because also it's having it's like it's like a very big like watch a moment for like you know new big deals being signed yeah the we already saw the trend start where podcast just started to pop up more and more out of nowhere anyway it became a popping thing again so I mean you add on the fact that there's money in the game people are thinking complete everybody who has a podcast are like holy shit like they weren't that weren't even thinking about that kind of thing it just automatically just should change your perspective I get there's nobody who has a podcast especially anybody who has a consistent audience no matter what level that is they're now like yo this is a business opportunity it's the same as a shoot anything that starts more that could be niche the love like even sports right it was the culture in sports when people were making $30,000 a year or barely making more than anybody versus now you're making hundreds of millions right and now it goes from I have my my godfather was like he could have went to the league or he but his mom was sick so he rather just get a job closer to home right so he can take care of his mom you try you try take that till today I need to go to the league so I can take care of my mom right yeah yeah like it's a different level of money and people are farming their kids to go to go to the league and now I think people will be farming maybe not necessarily training their kids for a podcast all the there are people doing that with their kids and in terms of influences and take so yeah there'll be people a lot more strategically like saying oh no we're not just having fun conversations it's we can get some money we might not get a hundred mil but we can get a mil we can get 400,000 there's it's gonna be interesting and I think content as a whole though but people I don't think artists felt it as much as they should but that was a big win for content as a whole for anybody who notices and pays attention to the fact that that showed a sense of value alright like Drake should be looking at that alright everybody should be looking and then start realizing oh shit my content is just like Beyonce was with the Coachella and she showed that to Netflix like all those things are like okay hold up no this content is worth some money like oh I can't just just I just perform at Coachella and take the the performance fee I can get less on the front end it's like anything else and then resell us on the back end for fifty million dollars more than they would have paid me just to perform and it's something I'm already doing wait what you know that the content the way we think about content has to change and it's not just a podcast thing it's the mat work


All right, you are still watching Waze every year on July 14. France celebrates Bastille Day, which has historical and cultural significance. It honors the Bastille Storming in 1789, which marked a turning point in French history. A great celebration of Bastille Day 2023, complete with customary activities and a special appearance by the Indian Prime Minister, Narendra Modi, was what happened on this day, today in history, on Arredo. This is the time you wish you were in Orleans, France, because they would do so many activities. And they might actually do tonight, actually. They always have those fun activities that they plan out for days like this. All right, so Narendra, what did you find first in the news? OK, when I thought this way, I'm like, time must be really, really hard in this country because for someone to go this extent, then, which is, I don't know, it's really close to an hour so far in this country. OK, so a man arrested for selling his three children for $1.5 million in reverse treatment. And the reverse aid police command had arrested one Michael Chal, alias Ten God Ikweme, who allegedly took advantage of the deafness of his wife to sell their three children for $1.5 million, and then he even sold them according to their ages. So he sold the five-year-olds for $700,000, the three-year-olds for $350,000, and a day-old baby for $500,000.  I can't, I don't know, I can't just understand. You see how? You know people like that, they believe that the way I got these three I would get another set.  We don't think it's possible without the children. At that point, maybe she might not agree, but at that point, what he's thinking is survival, what do I need to do to be able to make money? So he hears that people are doing this kind of things. He's not thinking about the fact that these are actually his children, they are not adopted children, they are actually his blood. His blood? It's actually strange. I know that what's going to be a happy problem. How do you even buy children from them? Why is the baby factory business still booming? That's why people buy children. Because a lot of people are desperate. In fact, the one that got the day-old baby is the biggest winner. That's the one who was no more excited. You understand, it's the biggest winner because the day-old baby, that baby has not interacted with anybody yet. So it's easier for you to even just integrate quickly. Maybe the five-year-old will know that this is not my parent or whatever. It's very sad. But you see, I don't even know how to categorize this crime. I wish we had a lawyer, but I don't know how to categorize it. Because it's their property. So to him, in his mind, and have three cars, I just want to let them go. And instead of suffering, let me get money for it in return. For 1.5 million. So he sees them as... What do I mean? He's not looking at them as human beings. He's actually seeing them as properties that he owns.  You give him opportunity again to say, even your wife, if I can give you 3 million, he would gladly observe. Because this woman now can't even express herself because apparently she's had her hair in her hands again. It's sad. It's very sad. And the truth is, not to put more petrol in the fire, but it's going to get worse.  Because it's already very bad as it is, but it's going to get worse because now, everybody will look for opportunities. Remember one story we took? I can't remember which part of the African countries that they sell their toes. That the biggest is the most expensive and all of that. All those things are in the bid to survive. If I have 10 toes, who 10 toes have? I'll go sell for my money. All right, so my story is just like a news flash because we don't really have so much details on it. But I thought to mention it that the Nigerian Air Force, one of their fighter jets had crashed today in Makodi, Benres State capital. And that's according to the punch. And they say that these details are a bit sketchy because they don't really know. I said the filing of this report, they don't have so much details on it. But the good news in this is that two personnel of the Nigerian Air Force onboard ejected unhurt. So it's possible that they used the parachute or whatever it is, but they were able to come out of the plane before it crashed. So I'm happy that's good news because again, I remember when, I think many years ago, was it 2019, one of the stories we took in the news was military training when they were jumping from, and the guy jumped and the parachute failed. It didn't work. Although I think he survived. I'm not so sure again now because it's been a long time we took that story. But we'd like to know more details here because I was on Instagram and I saw videos of, I think a plane crash and nobody died actually. I mean, that one really burnt and then nobody died. They were able to ever quit everybody before anything happens. And that's usually not really the case. So when you hear things like these that they were able to eject themselves and they are safe. So we don't know how many of them were on board. So at least some were able to eject themselves before the crash. So we'll look forward to probably checking out on the story if we get reports again in the news about it. But on that note, let us take a break. As you can see that today, I'm very chill. You see, we're on this day. Let's see how we can speak to employers, how they can make the employees a lot more comfortable at work, making sure that they're holistic. And I mean, this is now putting the spotlight on their mental well-being. Because again, if you truly have happy stuff, delivery would just be great, yeah. All right, stay with us over right back.


I like computers a lot and I want to learn more about it because I want to study computer science so that's my career that I want to have in the future. The only thing I need help with is turning the computer on and putting the headset on my head. Other than that I can operate just about anything else by myself. It's a real accomplishment and you really feel proud of yourself when you're actually able to make progress and do something without having to ask somebody else.  Besides an interest in technology, what these people have in common is mobility impairment. But each one is different and so is the way they use their computers. It's pretty rare that there would be a one size fits all technology for people. Each person with a disability with a mobility impairment is going to have a unique setup that's suited to meet their needs and they need to be the end client that decides, is this technology working for me or is there something else that I'd rather use that would suit me better. An individual's mobility impairment may or may not be obvious to others and people with similar medical conditions may need different types of adaptive technology. The important thing is to work closely with the person using the computer to figure out the best fit. Pay attention to the individual and what he or she needs both through observation of her in the actual environment in which the technology is being used and also through consultations with the individual. We'll show you some examples of adaptive technology that have been used effectively by people with mobility impairments and we'll start with getting to the computer. You can't use a computer if you can't reach it. You have to be able to get in the building, get through the aisles and sit comfortably at the work station. Computers at work and at school should be in locations that are accessible to people using wheelchairs. Physical access to buildings, labs, classrooms, all of that is extremely important because this technology, no matter how good it is, is completely unusable to a physically disabled person if they can't get to it. And that means having a ramp if there are stairs, having an elevator if there are stairs inside the building, having enough room between aisles if it's a computer lab or having enough room in the hallway. The furniture makes a difference too. It's important to be flexible in the way you position keyboards, computer screens and table height. Adjustable tables can be cranked higher or lower so that the monitor is at the most comfortable height. Keyboard trays can move up and down or tilt to make typing easier. Some people with mobility impairments don't have the flexibility or range of motion to use a standard keyboard. Fortunately, there's a wide range of alternatives available. Some of those are already built into current popular operating systems. The fact that there are some basic features built into operating systems is really important. There are some very simple things that can be done using control panels, accessibility options control panels, that give access, basic access to the keyboard to the operating system. For example, someone using a single finger or a mouth stick wouldn't be able to type two keys simultaneously, such as control and something else. There's a setting that allows those keys to be entered sequentially. Another setting eliminates repeated keystrokes for someone who keeps a key pressed down too long. And features such as autocorrect, which are common in word processing software and other applications, allow the user to abbreviate long words or even sentences with a brief letter sequence. Once the abbreviations are set, they can make typing faster and more accurate. There are also physical adaptations to consider. For example, a key guard. The key guard agrees that it fits everything keyboard, and it has holes for each key that prevents people from typing a key they don't mean to hit if their movements are not controlled. For people who have limited range of motion, a mini keyboard may be helpful. There are also left and right handed keyboards, which can be used with only one hand. For someone with good range of motion, but poor dexterity, there are keyboards with extra large keys. For someone who can't activate a keyboard physically, a virtual keyboard may be useful. This appears on the computer screen as a picture of a keyboard. The keys can be activated with a mouse, trackball, or alternative pointing system. Some virtual keyboards may include features such as alternate key layouts or word prediction software. Word prediction programs help people type correctly and more quickly. The program prompts the user with a list of possible word choices based on words that have already been typed. Some programs collect new words as they're used and work with the user's common vocabulary in making predictions. I throw in a letter, let's say I throw in a T, and five words that start with T will pop up. The most common ones that I use, they'll pop up and I'll click on it and it'll just print it out. Graphical user interfaces are everywhere, and you need to have some sort of a pointing device to access the material on the computer icons, clicking, pointing, all those things. So you either need to use a mouse or find an alternative to using the mouse. Trackballs are a good place to start. The trackball's control surface is easier to manipulate than the mouse. On some trackballs, buttons provide features such as double clicking, click and hold, and other commands. They can be used on the desk or for people who use their feet instead of their hands on the floor. People with good head control but no use of their limbs can use a head-controlled pointing system. This system uses infrared detection and a transmitter or reflector worn on the user's head. It translates head movements into pointer movement on the screen. This can be combined with an on-screen keyboard for full computer control. Well, the headmaster that I use, it just controls the mouse, the cursor on the keyboard, the little thing that I blow into. That's the button click. Switches work with a box or emulator that sends keyboard or mouse commands to the computer. They come in a wide variety and can be controlled with nearly any body part. Some people will use a switch mounted on an arm and this arm could be mounted so that it's in just the right location for users. Some may use one switch that's just an on-off switch that then interfaces with the computer. Most often that is used in a way that it's either controlling an on-screen keyboard so that they can do the standard keystrokes. And then software can also be used with that same switch to control the direction of a mouse and then the right and left mouse clicks using that same switch. Scanning and Morse code are two of the input methods that rely on switches. With scanning, the user activates a switch that brings up an options menu on the screen, then continues to activate the switch to make specific choices. Morse code uses a sip and puff switch where dot is a sip and dash is a puff. Special hardware and software translates Morse code into a form that computers understand. Any switch system should be mounted by a knowledgeable professional. So it's useful to think about a wide range of accommodation needs for people with mobility impairments. People may use a light activated switch near their eyes that they can do a long blink or a short blink. And then with that input device, even the person with that severe limitation can control a computer. They could use an on-screen keyboard and write to somebody. They could go to the web, do things everybody else is used to using on the computer. Others may have more functionality. They may be limited from, you know, they can move their head, they can speak fine, but they can't do anything with their hands. So perhaps they would use speech recognition to control a computer or use switches that could be located behind their head so they could click, you know, left or right button or maybe even use their head to control the cursor as well. I'm a junior this year. Speech recognition products allow users to bypass the keyboard completely. I use a program that helps me type. Whatever I say, it types. It's a microphone. I talk to the microphone and it types it out on the computer screen. Speech recognition software converts spoken words into text on the computer. The person using it speaks into the microphone in a normal manner. This type of system requires that the user train it to recognize their unique voice. The truth is... It's also important to correct any recognition errors that the system makes. Most of us are intimidated by computers. To use speech recognition technology effectively, it's important to have good voice and breath stamina. Good reading comprehension is also helpful because there are always corrections to the program's text output. But it gets easier with practice. This research effort confirms what so many of us believe. Reading systems, which involve both hardware and software, are helpful for people who find it difficult to hold printed material or turn pages. A scanner converts hard copy into a digital image, which is then converted into a text file that is recognized by the computer. Next, the words come up on the screen at the same time that a speech synthesizer reads them. The most important part of selecting adaptive technology is to recognize the needs of the individual using it. The best adaptations are the ones you choose yourself. It's all about personal success. The technology that's being adapted is now quickly becoming the core of our modern economy and also our social life. Without access to the technology that allows us to access these new means, it makes it nearly impossible for the disabled individual to participate fully in society. For more information about IT accessibility, consult www.uw.edu. The content of this presentation is based on works supported by the National Science Foundation under grant number 9800324. Any opinions, findings and conclusions or recommendations expressed are those of the authors and do not necessarily reflect the views of the National Science Foundation. Copyright 2015, University of Washington. Permission is granted to copy these materials for educational, non-commercial purposes, provided the source is acknowledged.