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Hello and welcome back.

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In this letter and I'm going to show you some of these uh points differences between greetings hero

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programs setting preferences how to view and use this assembler window pane while the entry points and

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so the basic commands to step over the program's line by line.

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OK let's get started now.

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If you go back and look at the place where you download this cracked me it is stated by the author which

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you see a programmer and that this is a very easy fly What do you mean by fly.

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Flag is a kind of password.

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You can also view it as a serial number which you're supposed to find from the program.

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Let's take a look at a program which we downloaded here.

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If you were to double click and run in

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he would just open and close.

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Very briefly so this shows that it is a command line interface program which you need to use run from

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the command from.

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So you need to open up on prom and run it.

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So that gives us he first example of the differences between GRI ends here.

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Programs great programs graphical user interface programs which are those programs.

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We have a window and the mouse.

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It can be used to click to run our two minute program CNI programs command line interface programs such

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as this.

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So when we first start to learn about software cracking we would like to keep things simple and learn

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how to create come online interface programs first and then later on we can move to the graphical user

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interface.

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So this Mexican great me is a command line interface program so to run the program we need to open the

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command line from initially how did it then.

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So you click on the bottom left corner right click on it and look for command from and then open a command

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problem and then issue navigate to this location of the uh correct me.

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So you can type C D E C colon backslash followed by this.

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You can type it out manually type this

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or an easier way is to simply type C D and then from here.

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Copy the path and here correctly base and then presenter immediately you enter the correct folder that

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contains your correct me.

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So not to run it from the command line prompt.

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First you must list the content of this directory by typing D I R and enter and you will see the name

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of your correct me which is called on Title 1 EIC not to run the program from the command line you do

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something like this.

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He would take the name of the program.

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He didn't have to spell it out in full.

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You can just type you in and press the tab key on your keyboard and you will complete the name for you.

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Now we just have to press enter to run it and you can see you can see an output see try hard.

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OK so this is why it shows you that you need to find a way to get hold of the flag.

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The zero no password or whatever you might like to call it.

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So in the among hacking circles and cracking and groups this trying to find out the sheer number or

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the password or some secret phrase is called Capture the Flag CTF in shot CTF.

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So this uh tracking

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activity is something like trying to capture the flag as well.

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So that's why this auto series is a very easy Capture the Flag.

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So at the moment this program is teasing you.

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I seem to try harder.

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So OK now I will show you how to capture the flag.

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So what we going to do is firstly analyze this program which I've shown you how to do in the previous

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lessons that used to open in view of the i.e. so in your point of view i.e. you will show you the entry

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point any emission base.

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So this is a hint to tell you where there's a program start to run and what are these numbers.

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These numbers are memory addresses KMI closes and show you.

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So now we are going to open this cracked me using the x 64 BBG so I get and drop it here and run.

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Okay so now is the moment you open this program you can see so this started by his past day and it is

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past at this entry point.

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This is not entry point very well.

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It is starting off the operating system.

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It is not yet your program.

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You haven't even enter your program yet you are in the operating system.

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So how do I know that.

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Because early on when we analyzed a program by opening of even the IEEE the IEEE showed us that the

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entry point is at this location in Mission bases at this location.

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So an image based his the address you enter your program starts but it is not the entry point to get

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the entry point.

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You must take this no which is in hexadecimal.

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Add to this number the image base and that would give you your entry point.

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So the entry point should be 0 0 4 0 1 4 He's 0.

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That is the entry point.

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Okay.

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And from here we can reach the entry point.

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I'll show you how to do it.

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But first things first we need to set some references for our access before the G so to set the preferences.

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We go to Options and top here click on preferences and we want to uncheck this the s convex or there

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is no need to know what this means because the only gets more confusing.

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But trust me you don't want to have this checked.

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So for all your tracking projects we should sure this is unchecked and normally you only have to do

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this once and even will remain unchecked.

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So yes unchained is the second thing you want to do is go to the accession.

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So this events there now would a sessions that.

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And here you are going to enter a range of exceptions and what I section say exceptions are errors that

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arise in the program.

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Now X 64 DV G is able to handle any errors that arise.

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It is a debugger after all but for cracking solver purposes we want to truly roll back to the program.

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So we are gonna tell X 64 DB g to ignore all errors so that the program will handle it and we can analyze

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his behavior better.

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So we have to add these exceptions here.

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So click on Add range no exceptions.

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Range from the numbers 0 0 0 0 0 0 0 0.

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There are eight zeros there and here.

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It FS have have have have.

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For f f f.

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It s so this.

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Okay.

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If you have these so this means that you won your SCC for debugger to ignore all these errors and truly

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back to the running program to handle it so that we can observe its behavior.

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So now just click save and we are all set.

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So now you can see the program pass and this uh operating system address.

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So let me explain to you what all this means.

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Now the first column is known as the address address in REM memory.

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The second column is your quote in binary form written has hex numbers.

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If these numbers are actually in 1 0 1 0 1 0 and so on.

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But to make the numbers shorter we put it in hexadecimal form.

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So this actually known as COP quotes on machine inputs of course.

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So for the most part we are just gonna ignore this our codes and in the third column is your interpretation

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of this of codes in human readable form.

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So this is this human rule form is what we call assembly language and that is where we get a name.

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This assembler from this program exists for the BBG is this assembler because in this assemble the machine

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code into human readable form car assembly code.

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So from code on wishing code to assembly code or assembly program.

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And this is what we are looking at.

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Most of the time because this is human readable so the tech column in the fourth column here is the

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comment column.

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The comment column sometimes is populated by strings like this.

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You can see the comment.

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These comments are inserted helpfully by existing for the BJP.

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And it makes our job much easier because the excessive for the BJP has interpreted some of the meaning

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of this symbol and show it to us here and we'll be making our use use of this quite a lot as we go along.

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Now there is one more column which I mean meta which is over here and this is something like a graph.

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So this graph here tried to map how the instructions are really jumping from one location to another.

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For example you see this instruction would jump from here to here.

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This and many of you jump GJ all these instructions that you in Jamie's to jump.

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And yeah many of them you can see here jump here and then here's another jam.

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All those things studying J means jam and I'll get I'll explain that in greater detail later.

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OK so this is how you interpret this assembly window or this assembly view.

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OK.

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So now we start whenever you start a program he always starts in the operating system here.

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And if you want to restart the program you just click on this then restart and you start all over again

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in the operating system.

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Now realign our brain system.

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We are not yet in this entry point your entry point is entry point for your.

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Correct me sir.

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So we do not one to correct the operating system.

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We want to create the correct me sir.

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So we have to go to this image address location so remember this is address.

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So we have to go to 0 4 0 0 1 4 0.

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So to go there there is a shortcut.

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Way to go to directly.

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That is by clicking this button front or pressing F nine on the key what we do the same thing.

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So you click this now or press F nine and immediately watch the address as I click on this.

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It goes straight to the entry point.

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So this entry point is supposed to be your entry point for your program.

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All right.

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4 0 1 4 3 0 OK.

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So we are correct.

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So we study the entry point for one for each zero and you can compare the IEEE take this number at this

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and you get this number for 0 1 for each 0.

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So this is how you can know where is the entry point supposed to be and to go there.

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All you need to do is restart the program.

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Take this one time and you will land on your entry point sometimes.

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This command does not show entry point here.

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So sometime this might be just be a blank.

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So if this is a blank even you want to confirm whether this is ready to go the entry point always refer

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back to the IEEE the IEEE detected.

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Easy.

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We'll show you the entry point.

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Just take this hex number add to this Can you get this entry point.

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OK.

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So that is how we launch our program into the entry point.

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All right.

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So the next thing I want to show you is how do we step through all these instructions to the step to

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the instructions.

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We will press the F A key on the keyboard.

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Or you can click this key this button which means step over so f it key is to step over F nine is to

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run what is the difference if you click f if you click this button and run or press F nine you will

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run in the program.

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That means you will go through the program without stopping and your program has terminated.

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As you can see on the top bottom left on the bottom left corner committed to debugging stop.

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So we doing 1 2 press F nine all the time.

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That's why we need press f it after pressing F nine to hit.

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How do we find.

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So let's try again.

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We start now we are starting to go to the entry point.

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What do we do.

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We press F nine on the keyboard click on this button run and we land in a two point okay.

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So now we want to step through line by line.

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We should press f 8 or this button so we keep pressing f here or we click on this but then he will move

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from one instruction to the other in sequence from top to bottom.

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Sometimes he may jump all over the place let's take a look.

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Okay.

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This call will go to this address 4 0 2 6 8 0 and an income back continue here okay.

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So you go.

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You go to the address.

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Come back here in this step.

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Call

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keep on pressing f it.

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All right.

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Have you come to our income remember I mentioned earlier all those instructions starting G jump instructions

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and there are two types of instructions that jam.

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One is conditioner.

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The idea is unconditional.

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This instruction is a condition on jam.

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This instruction GMB is unconditional and.

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What is the difference.

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Conditional income would depend on the test just above it.

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So based on the result of this test it is testing two registers.

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Here is testing something different based on the result the test.

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He would decide whether to jump or not to jump an unconditional income does not depend on any test.

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He would jump straightaway.

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That is the meaning of unconditional income.

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So now we are here.

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As you can see let's continue this step repressing f it so now it is at this point.

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And how do we know whether you were German.

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How do we know.

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We can look at this and look at the status box here and use this gem.

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He's not taken.

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That means it will not jam and another indication that he went on jammies who look at this line it is

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going to jam this line will turn red.

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This line indicates the jam.

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Look it is a long jump right to the bottom somewhere.

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But we're not going to go there now.

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So it is not going to jam all right.

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So this is confirms it as well.

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It is not going to jam.

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So if you press effort you would just go to the next line without jumping.

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Watch.

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So I press f it quickness.

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True enough he goes to the next line and the keyboard pressing f it see what happens f f f g f it.

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Okay so now you notice this line turns red meaning that this jump will be taken because this turns red.

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And then a confirmation is here.

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Germany has taken notice.

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So this is called unconditional John.

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It does not depend on any test and birth before it.

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So now this press effort and c jump and even tells you where it is going to jump to.

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It is going to jump to this location 4 0 1 2 1 6 here 4 0 1 2 1 6.

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You can see the two arrows one here and another arrow here.

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So this this column tries to draw a better graphical view of the jumps.

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Here is a simplified arrow to show you the jumps and you see you notice the arrow can be pointing down

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and some areas are pointing up.

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This means jump up habits.

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This means jump downward so did not look the direction the arrow tells you where you reach it will jump.

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Now this kind of thing jumps normally loops that give given looping for certain periods of a certain

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number of times.

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All right.

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So now you're here and you're going to jump unconditionally and this will work in front.

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Here is a name of a program which is Title 1.

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So normally the the and the FCC for DG will put your program name in front.

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Put a dot followed by the address where you will jump to case.

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Now if you press F it was going to jump all the way down to 4 0 1 2 0 1 6.

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As mentioned here.

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So let's do it now and see what happens syllogism.

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True enough so it's taken a jump.

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So now you press heavily gay and include ongoing.

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Now let's let's analyze this now.

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Press TV Okay.

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Is it going to jump or not why do you think yes I think you you will go.

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You have got it correct.

250
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It is not going to jump because firstly this line did not turn red.

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Now remember this is average.

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It is but he didn't turn red.

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So it is not going to jump in error.

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Another indication is over here Jim has not taken indicating that it is not going to jump all right.

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He can confirm it by pressing epic and issue move to the next line below it.

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And true enough he moved the next line below.

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Let's continue pressing Evy Evy ethically Evy now what do you think.

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Is he going to jump yes it is not going to jump.

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Why you didn't and read the line in it and read.

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And the indication here is jump is not taken.

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So.

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Press Evy

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yes this one would jump because he turned red.

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And the indication shows jump.

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He's taken so less passive he so is very is going to jump to you is going to jump to 4 0 1 4 8 1.

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So he's going to jump way below down here for 0 1 for it.

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Right.

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OK now I already move.

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Scroll down with my mouth.

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How do I go back to the last location.

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Very easy CAIB.

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Click on it and you go back to the last place where you stop.

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So EIB is call an instruction pointer to the e in front means extend that extended instruction pointer

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all the e front means extended.

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So EIB whenever you're lost I say I screw all the way down and I want to go back to my last indication

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why I.

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I just I quickly this and I go back here now and continue stepping.

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So when I press f it he will jump all the way to 4 0 1 4 1 as do it.

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See he landed here.

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So now I press f it again and continue to go like this.

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Now what is the difference.

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We didn't call and jam call also does a jump but he doesn't show you if you want to see jump you need

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to press another key but I will show you how should that to you in another lesson for now I just want

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to introduce you to jumps.

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What jumps so we do call and a lesson so no let's press f it

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OK.

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So a jump here feet again this angry job because it's Ray.

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Yes is mistaken

289
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call John Jim so each year so all of the assembly code is just about jumping in calling this it jumping

290
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calling Coco Coco.

291
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Jim no jump taken.

292
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All right fine.

293
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Jump OK.

294
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So this is going Abbott's effort.

295
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He even jump because the arrow didn't read.

296
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OK this we jump with it and red.

297
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And he also says jump is taken.

298
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So he jumps up

299
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hub again.

300
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So this is a loop.

301
00:24:39,520 --> 00:24:48,620
So it would keep looping until a sitting condition is met OK so we can keep on pressing and pressing.

302
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F f f it.

303
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And eventually he will terminate the loop.

304
00:24:55,600 --> 00:24:57,000
And where do you think it is.

305
00:25:00,360 --> 00:25:01,880
Where do you think in the loop with only

306
00:25:05,020 --> 00:25:07,280
you can give on pressing and keep trying.

307
00:25:13,770 --> 00:25:14,100
Okay.

308
00:25:14,120 --> 00:25:15,620
This is one way to make a.

309
00:25:15,750 --> 00:25:19,190
You even go out of the loop up here all right.

310
00:25:20,160 --> 00:25:21,540
So there is one we

311
00:25:25,420 --> 00:25:35,010
all we can press f it hold press area and key one hole and using it will go faster eventually you leave

312
00:25:35,010 --> 00:25:35,620
the loop.

313
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Once they lift a loop released the key have it.

314
00:25:38,610 --> 00:25:39,910
Now I'm holding it.

315
00:25:40,180 --> 00:25:40,810
OK.

316
00:25:40,830 --> 00:25:43,590
It has come out of the loop and now it is somewhere else.

317
00:25:43,590 --> 00:25:43,890
OK.

318
00:25:43,890 --> 00:25:54,340
So now he's over here and the jam is not taken so press ever it again and you can see he keeps on going.

319
00:25:54,360 --> 00:25:57,880
So this is how you step through the.

320
00:26:00,830 --> 00:26:09,460
OK so eventually if you keep on pressing f ed you will reach the point where the message try harder

321
00:26:09,470 --> 00:26:14,900
will be shown here but you might miss it if you press given pressing and releasing and you missed it

322
00:26:14,960 --> 00:26:17,060
sooner because of you.

323
00:26:17,060 --> 00:26:21,350
CORNISH pressing f it without releasing so it missed it.

324
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So in the next lesson I will show you a way in which you can boss the program using break points.

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So that's all for this video.

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How to see you in the next one.

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Thank you for watching.