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All right.

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Welcome.

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So let's move on to project number two.

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The first project all we did was write a piece of assembly code that tense on the red and indeed on

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the launchpad it keeps it on.

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That was a bit boring I know but it's a good starting point.

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At least now you know how cheap apple works in assembly.

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And this one here we're going to add an input pot to this first code and we're going to turn on the

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light by pressing a button.

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So there will be a bit of interaction there.

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So let's get started.

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So let's create our new project like we always do.

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We come over here.

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New York Vision project.

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Yes.

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I want to save this and create it in this folder create a new folder and keep it in there.

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I'll call this red.

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I just call it red switch.

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Something you can call it what you want to call it this way

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then I'll double open.

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And then create the name red switch.

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It's a strange name

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call it red on the school switch

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and save her like this.

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And our microcontrollers T for C 1 2 3 0 h.

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And then it took over her we choose.

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Then there we have it.

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Then all we have to add over here is the CMC score and then for device we got to start up like this.

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And okay we have her we have our target.

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So we have to create a new file and then say the US main dot s and click here to expand and then double

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click here.

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We come here to load our file.

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Remember Carrie Lee the file only exists on your desk.

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You have to make it part of your project and to do that.

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You have to come here and then double click to file to your project.

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So in order to make our file visible let's just go to all files and I'll file this man s overhead like

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this.

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And now it is part of our project and we can find the.

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So we're all set.

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Let's crack on.

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So let's recap from of our previous lesson in our previous lesson we dealt with four registers we dealt

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with the clock gains and register which is used by mood in day microcontrollers to save power.

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They don't turn on all the hardware to keep the hardware off when you need it.

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Then you turn on the clock.

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That's the clock gating mechanism basically.

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So we use that register and then for our a good part.

47
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We used to keep a data register the GPA or direction register the cheap I O digital enabled register

48
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at these four registers are basic registers to turn on GPA.

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But to do something more we would need to unlock the entire port Beth.

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So we would have to add three more registers with one key.

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So let's continue ok.

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These are the registers we started with from our first our first example.

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Today we'll be adding four more registers.

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We'll be adding the switch the switch on the board as it turns on when the current is low.

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So it enables on low.

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So because of this we have to connect and pull up resistor to the switch.

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We can do this physically.

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We can add a resistor to the pin physically using a small circuit but we don't need to do this code.

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There is a pull up resistor register and in the microcontroller.

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So we just need to enable this register.

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Also we have to use the the commit register of port f this the thing some pins on the port F are connected

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to the deejay tag which is used for debugging hardware and the NMR.

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And these are very very serious important part of the microcontroller.

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So some pins are connected to these parts and because of the importance of the microcontroller has locked

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down these pins by default.

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So that we don't ride to these pins mistakenly.

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So if we want to use them we have to enable them and by well I don't mean right into their digital enable

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register.

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We have to make them comfortable.

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This is where the comet register comes in to the to register allows you to be able to commit a value

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or data to these registers.

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And in order to use that commits register you have to unlock the pot.

73
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So there is another register known as tick pot f lock register and we have to use this register to unlock

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the commit register.

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So let's crack on in fact rather than go in there and get the error to come declare let's just declare

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our register now.

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So we have cheap or port F P U R which stands for pull up resistor and we give it a symbolic name.

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That's the symbolic name at this this the number of the register.

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This the address basically 2 5 5 1 0.

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Do not worry you can find this in the data sheet if you want to.

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I don't want us to keep going back and forth.

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It would print long this video.

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So I just went into the data sheets and collected this on your behalf.

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So we have this one to get a lock Reg stock.

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The one I'm talking about

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and this is E Q You 0 x 4 your 2 5 5 2 0.

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And then we have the commit register one of our new registers.

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If she'd gone on this call here or F C are on a school

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in queue you then how she would X of course you 2 5 5 2 4.

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And then finally we need to lock key.

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If you want to unlock something you definitely need a key.

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So let's start a key.

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Let's give a symbolic name to that key.

94
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Let's just call it creepy eye or lucky GPO lock key.

95
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And then we give this this the value of that key for C

96
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for F for three for B.

97
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So these are when you registers these will be used in this in our chippy IDE or in it subroutine to

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initialize the board and make it ready and we will be it on the red LCD.

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So how about we just give it a symbolic name as well.

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But I'm going to do this.

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I'm going to declare right here symbolic name right.

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And you can you add know value to X to remember.

103
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I think I should keep putting this there until you get used to it.

104
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So this work this basically means because red is connected to P. f 1.

105
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So this phase 0 is for PFC row and this P F 1 p.m. 2 p.m. 3 2.

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And we would have to delay a bit to make all micro controller responsive and to make it able to read

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inputs we press continuously.

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We're going to give an approximate value of one fifth of a second based on the frequency of our microcontroller

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which is 16 megahertz.

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So I'm just going to give this symbolically sick if five.

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Which means second divided by 5 and 2 and the value is 1 6.

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Once you are sorry.

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One two three four five.

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And just put a comment here for you.

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Second divided by 5 to now.

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Yes we've declared all the stuff we need to declare.

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Let's get into our assembly.

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So let's start.

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Start with support directives.

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Stop by area.

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Space space.

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This dot text and this comma and there's the code area number.

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And let's make it read only and there's a line line in the codes to in using thumb instruction set and

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let's export main again to make it accessible by the dot by the time the dot s file that we saw just

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in the previous I don't lesson show we call it man don't come here and declare man.

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So just like we do.

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Let's break it down let's create a fair subroutine to initialize we call this G P.

128
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OK.

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Too much space.

130
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Let's just keep it close.

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Cheaply I do.

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And then it let's go.

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Don't have to initialize of course the contents of to cheap.

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I do it.

135
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So first we start really on the clock.

136
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Register healthy the young 1 more then system 1 true.

137
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I'll see you soon.

138
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Keep your eye on the school.

139
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Then slowed our Tier 1 what we want to do we want to turn on the clock for what F which is 0 x to 0.

140
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So we apply to all operator are here.

141
00:11:25,280 --> 00:11:27,590
Don I'm sure you

142
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then no to share

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show.

144
00:11:49,630 --> 00:11:51,080
We got this settled.

145
00:11:51,180 --> 00:12:02,160
Well we have to do now this stalled and funding must you know restore stalwart source and then destination.

146
00:12:02,160 --> 00:12:10,920
Remember the difference between skull and mode is to forestall the first apparent is the source and

147
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the second operation is the destination followed.

148
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It's the other way round.

149
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So you've got this one down.

150
00:12:19,560 --> 00:12:31,470
Let's go to the direction register idea I want to go on this call.

151
00:12:31,950 --> 00:12:35,690
If I go on.

152
00:12:35,840 --> 00:12:39,370
So one thing I forgot to mention is ducks.

153
00:12:39,380 --> 00:12:50,210
Which one is connected to a four and switch two is connected to PFC or shall I just write it that it's

154
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a comment

155
00:12:56,290 --> 00:13:08,190
for and then yes then a comma has changed to that I would just like to manipulate ships to.

156
00:13:08,240 --> 00:13:09,170
PFC you

157
00:13:16,380 --> 00:13:16,810
OK.

158
00:13:16,830 --> 00:13:27,840
I'm just competition for her and what for actually implies this in order to enable care for the basically

159
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half to keep us here of course.

160
00:13:30,830 --> 00:13:37,400
Remember when we set in that direction register when we set it too low it means we're telling the microcontroller

161
00:13:37,400 --> 00:13:41,730
to make that particular pin an input pin we'll set it too high.

162
00:13:41,730 --> 00:13:43,860
We're telling it to make it an output pin.

163
00:13:44,220 --> 00:13:53,090
So over here in that direction register it stays the same us to the previous program we wrote goes well

164
00:13:53,090 --> 00:13:54,410
we keep it serious.

165
00:13:54,510 --> 00:13:57,450
We basically telling it to keep it as output.

166
00:13:57,780 --> 00:13:59,980
So we're going to do that.

167
00:13:59,990 --> 00:14:02,470
We're going to use the move goes to value.

168
00:14:02,480 --> 00:14:13,010
We're going to write in it's an 8 bit value and we can use to move a creator of this show to X and then

169
00:14:14,940 --> 00:14:22,360
she wrote to us it implies it's been 0 0 0 0.

170
00:14:23,950 --> 00:14:24,920
Juicier.

171
00:14:25,370 --> 00:14:28,400
Once you show this one here is fine.

172
00:14:28,400 --> 00:14:31,750
Here is what a switch course this is you.

173
00:14:31,820 --> 00:14:33,950
One two three four.

174
00:14:34,790 --> 00:14:44,630
And because it's zero it means finished output and then this tool for store is a source destination

175
00:14:44,900 --> 00:14:47,680
like this shell that's been covered.

176
00:14:48,190 --> 00:14:59,960
The next thing we have to do is to connect a pull up resistor to the switch and we'll use the P R ratio

177
00:14:59,960 --> 00:15:13,100
for this because you can dial F P on a longer school.

178
00:15:14,240 --> 00:15:16,070
And this one too.

179
00:15:16,070 --> 00:15:21,290
It's an 8 bit farther we want to move so we can just move the stage but 12

180
00:15:24,140 --> 00:15:28,060
that into our shoe and what we want.

181
00:15:28,980 --> 00:15:42,230
It's this guy her show this rather easy just have 2 1 2 2 x 1 share then I'll just pour alcohol for

182
00:15:42,230 --> 00:15:43,160
you.

183
00:15:43,160 --> 00:15:56,100
What this means is 0 0 1 0 0 0 2 so we know this is part 4 and then was unable to pull up retches pull

184
00:15:56,100 --> 00:16:05,520
up resistor here for remember this it resists that not a register is a normal resistor so restore it

185
00:16:05,820 --> 00:16:11,770
ness and restore by source are zero discrimination.

186
00:16:11,830 --> 00:16:22,190
1 so that's been covered the next step is to call to the pool at which to enable register let's do the

187
00:16:24,880 --> 00:16:39,010
TR 1 because you can go for f a thing always right in the image function takes quite a lot of time for

188
00:16:39,010 --> 00:16:39,770
the video.

189
00:16:39,970 --> 00:16:46,090
So in the next project that we'll be doing they're going to be relatively long project show what we

190
00:16:46,090 --> 00:16:52,240
will be doing is we're wedding type out the the inmates function together I'll just take it out once.

191
00:16:52,250 --> 00:16:54,700
Now you go through and then we continue from there.

192
00:16:54,700 --> 00:16:58,470
That would save us quite a lot of time for these two projects.

193
00:16:58,480 --> 00:17:01,330
It's very good that we do it together.

194
00:17:02,320 --> 00:17:06,540
So they serve and what we need is another age but.

195
00:17:06,700 --> 00:17:11,560
We want to move to our share and what we want to enable.

196
00:17:11,560 --> 00:17:17,130
We want to enable P F we want to enable people for the switch.

197
00:17:17,140 --> 00:17:18,050
We want to enable.

198
00:17:18,120 --> 00:17:22,460
If one who be for the end to do so.

199
00:17:23,030 --> 00:17:34,950
As you can guess except we accept hexadecimal 8 but you the one to look at this and could put the help

200
00:17:34,950 --> 00:17:37,470
I have for you.

201
00:17:37,840 --> 00:17:38,770
What would this be.

202
00:17:38,770 --> 00:17:44,010
This is ISSUE 1 seriously

203
00:17:46,970 --> 00:17:49,200
2 2 1 0.

204
00:17:49,330 --> 00:17:55,220
So that's what this implies and then restore it skull.

205
00:17:55,930 --> 00:17:57,530
Source register answer.

206
00:17:57,610 --> 00:17:59,440
Destination major stop 1.

207
00:17:59,690 --> 00:18:06,810
So now we have to use all we have to access to more Redish this we have to unlock it and then allow

208
00:18:06,820 --> 00:18:07,790
comment.

209
00:18:08,020 --> 00:18:10,030
She could do LTI.

210
00:18:10,210 --> 00:18:14,380
I want cheaply I F

211
00:18:17,720 --> 00:18:19,670
block on the school.

212
00:18:21,540 --> 00:18:28,110
Then and then since we don't need to perform any form of computation or manipulation we just want to

213
00:18:28,560 --> 00:18:31,830
take something from one register and put it into another one.

214
00:18:32,130 --> 00:18:35,930
You can just note this one into another register like this.

215
00:18:36,060 --> 00:18:38,370
And what do we call it.

216
00:18:38,370 --> 00:18:39,510
Recorded it cheaply.

217
00:18:39,520 --> 00:18:42,360
I'll lock both you or something.

218
00:18:44,060 --> 00:18:48,090
Let's see what name you gave it to right here to call you.

219
00:18:48,090 --> 00:18:51,120
Lock key so.

220
00:18:51,330 --> 00:18:53,640
This is a 32 bit value.

221
00:18:53,670 --> 00:18:55,850
That's where we use the LTE.

222
00:18:56,550 --> 00:19:05,940
We cannot use move for this move wouldn't work so we just load below the register in R1 and then load

223
00:19:05,940 --> 00:19:19,920
a key in our here and score and as we know you are one now with one locked in the last in the last register

224
00:19:19,920 --> 00:19:22,730
for it and it is still that cheaply.

225
00:19:22,730 --> 00:19:38,500
I will commit register and then do that by this GP I'll put on a school C and then.

226
00:19:39,270 --> 00:19:50,450
And what we want to do is to unlock say some 8 bit value into that value we will use in her father year

227
00:19:50,590 --> 00:19:51,600
school X

228
00:19:55,320 --> 00:19:58,090
and B.

229
00:19:58,260 --> 00:19:59,670
Basically what this means is

230
00:20:03,190 --> 00:20:05,220
it can say.

231
00:20:05,310 --> 00:20:17,020
Then finally restore the source and destination then a initialization is complete.

232
00:20:17,020 --> 00:20:26,220
What we want is to return from the subroutine using the x x and then return.

233
00:20:26,240 --> 00:20:29,660
So this particular video is getting quite too long.

234
00:20:29,800 --> 00:20:36,610
So we're going to end here and continuing the next video with the rest of the on the assembly code.

235
00:20:36,670 --> 00:20:37,500
Good work.

236
00:20:37,510 --> 00:20:38,070
See you.