1 00:00:00,000 --> 00:00:02,430 [MUSIC PLAYING] 2 00:00:02,430 --> 00:00:09,261 3 00:00:09,261 --> 00:00:11,760 DAVID J. MALAN: Odds are, you use a computer most every day. 4 00:00:11,760 --> 00:00:15,010 But what's going on inside of that laptop or that desktop. 5 00:00:15,010 --> 00:00:17,676 Well, inside of a computer are all these 0s and 1s. 6 00:00:17,676 --> 00:00:19,800 And you may have heard, indeed, that computers only 7 00:00:19,800 --> 00:00:23,280 understand 0s and 1s, or the, so-called, binary system. 8 00:00:23,280 --> 00:00:25,620 But if computers today can do so much, how can 9 00:00:25,620 --> 00:00:28,920 they do so much if they can only speak 0s and 1s and not 10 00:00:28,920 --> 00:00:31,230 even the entire alphabet that we humans have. 11 00:00:31,230 --> 00:00:33,000 Well, consider this. 12 00:00:33,000 --> 00:00:37,130 Back in our human world, you might recognize a pattern of symbols 13 00:00:37,130 --> 00:00:40,590 like this as the number 123. 14 00:00:40,590 --> 00:00:41,460 But why is that? 15 00:00:41,460 --> 00:00:44,670 After all, all I did was draw three shapes, really, three glyphs, 16 00:00:44,670 --> 00:00:47,160 or three symbols or digits on the screen. 17 00:00:47,160 --> 00:00:50,130 But each of these digits has some predefined meaning. 18 00:00:50,130 --> 00:00:53,850 If, in fact, if you went to grade school like I did and you learned numbers 19 00:00:53,850 --> 00:00:56,610 in this way, odds are, you might recall, that this rightmost 20 00:00:56,610 --> 00:00:59,940 column is the so-called one's column or one's place. 21 00:00:59,940 --> 00:01:01,590 Then this is the ten's place. 22 00:01:01,590 --> 00:01:03,510 And then this is the hundred's place. 23 00:01:03,510 --> 00:01:05,349 Now why is that significant? 24 00:01:05,349 --> 00:01:09,060 Well, the reason that 1, 2, 3-- that pattern represents 25 00:01:09,060 --> 00:01:11,970 the number we humans know is 123 is that there's 26 00:01:11,970 --> 00:01:13,830 a bit of arithmetic going on here. 27 00:01:13,830 --> 00:01:19,770 This, after all, means that you should do 100 times 1 plus 10 times 28 00:01:19,770 --> 00:01:23,280 2 plus 1 times 3. 29 00:01:23,280 --> 00:01:30,930 That, of course, gives us 100 plus 20 plus 3 or 123. 30 00:01:30,930 --> 00:01:33,540 In other words, there's a pattern to these digits, 31 00:01:33,540 --> 00:01:36,000 and there's a meaning behind each of their places. 32 00:01:36,000 --> 00:01:39,930 Well, it turns out that computers only, indeed, understand 0s and 1s. 33 00:01:39,930 --> 00:01:43,920 They can't count as high as 2 and 3 and 4 in the same way we humans can. 34 00:01:43,920 --> 00:01:47,080 But they use those 0s and 1s in exactly the same way. 35 00:01:47,080 --> 00:01:48,640 In fact, consider this. 36 00:01:48,640 --> 00:01:54,292 If we consider this pattern 0, 0, 0, to be inside of a computer, 37 00:01:54,292 --> 00:01:56,250 and that's what the computer is thinking, well, 38 00:01:56,250 --> 00:01:57,610 what number might this be. 39 00:01:57,610 --> 00:01:59,360 Well, the spoiler is that this is actually 40 00:01:59,360 --> 00:02:02,760 going to represent just 0, thankfully, just like in our human world. 41 00:02:02,760 --> 00:02:03,910 But why is that the case? 42 00:02:03,910 --> 00:02:06,030 And how can we count higher than 0? 43 00:02:06,030 --> 00:02:09,030 Well, in the computer world, realize that these places are just 44 00:02:09,030 --> 00:02:09,870 a little different. 45 00:02:09,870 --> 00:02:11,869 This is still the one's place, but this next one 46 00:02:11,869 --> 00:02:13,440 is not the ten's place anymore. 47 00:02:13,440 --> 00:02:15,239 It's, instead, the two's place. 48 00:02:15,239 --> 00:02:17,530 And this next place is not the hundred's place anymore. 49 00:02:17,530 --> 00:02:20,412 It's, instead, the four's place. 50 00:02:20,412 --> 00:02:22,620 And if you think about this, there's still a pattern. 51 00:02:22,620 --> 00:02:26,370 Previously, it was 1, 10, 100, and then if we kept going, 52 00:02:26,370 --> 00:02:29,855 1,000, 10,000 100,000, and so forth. 53 00:02:29,855 --> 00:02:31,230 And here, too, there's a pattern. 54 00:02:31,230 --> 00:02:34,210 1, 2, 4-- and if I kept going-- 55 00:02:34,210 --> 00:02:36,540 8, 16, and 32. 56 00:02:36,540 --> 00:02:39,930 And so, in our human world, we tend to use powers of 10. 57 00:02:39,930 --> 00:02:45,810 10 to 0 is 1, 10 to the 1 is 10, 10 to the 2 is 100. 58 00:02:45,810 --> 00:02:51,510 And in the computer world, this is 2 to the 0, which is 1, 2 to 1, 59 00:02:51,510 --> 00:02:54,780 which is 2, 2 to the 2, or 2 squared, which is 4. 60 00:02:54,780 --> 00:02:57,820 2 to 3 would be 8 and so forth. 61 00:02:57,820 --> 00:03:01,050 So all we're doing is changing the base that we're using, so to speak. 62 00:03:01,050 --> 00:03:03,930 Instead of powers of 10, we're using powers of 2. 63 00:03:03,930 --> 00:03:09,460 And so why is this number 0, 0, 0 the number we humans know as 0 itself? 64 00:03:09,460 --> 00:03:15,870 Well, again, if we just do the math, 4 times 0 plus 2 times 0 plus 1 times 0 65 00:03:15,870 --> 00:03:22,050 is, of course, 0 plus 0 plus 0 or the number we humans know as just 0. 66 00:03:22,050 --> 00:03:24,420 Well, what if we do another number altogether? 67 00:03:24,420 --> 00:03:27,817 Suppose we do this pattern 0, 0, 1. 68 00:03:27,817 --> 00:03:29,400 Well, what number does this represent? 69 00:03:29,400 --> 00:03:31,120 Well, if you consider the same columns-- 70 00:03:31,120 --> 00:03:33,030 1, 2, and 4-- 71 00:03:33,030 --> 00:03:38,490 this means we have four times 0, which is 0, 2 times 0, which is 0, 1 times 72 00:03:38,490 --> 00:03:40,180 1, which is 1. 73 00:03:40,180 --> 00:03:42,880 So this is the number we humans know as 1. 74 00:03:42,880 --> 00:03:43,380 All right. 75 00:03:43,380 --> 00:03:47,280 So not all that interesting yet, but what about the number 2? 76 00:03:47,280 --> 00:03:54,190 How, in binary, bi meaning two, and the 2 being a 0 and a 1, how, in binary, 77 00:03:54,190 --> 00:03:56,480 can I now count as high as 2? 78 00:03:56,480 --> 00:03:59,260 Well, if this is my one's place, this is my two's place, 79 00:03:59,260 --> 00:04:04,060 and this is my four's place, what digits do I want to put below those places 80 00:04:04,060 --> 00:04:07,840 if the only digits I have at my disposal now are not 0 through 9, 81 00:04:07,840 --> 00:04:09,940 but just 0 through 1? 82 00:04:09,940 --> 00:04:12,841 Well, I don't need a 4, so I can make that a 0. 83 00:04:12,841 --> 00:04:15,340 I do need 2 if I want to count to the number we know as two, 84 00:04:15,340 --> 00:04:16,590 so I'm going to put a 1 there. 85 00:04:16,590 --> 00:04:19,390 And I don't need an extra 1 because an extra 1 would give me 3. 86 00:04:19,390 --> 00:04:20,810 So I'm going to do this. 87 00:04:20,810 --> 00:04:23,650 And so a computer, to store the number we humans 88 00:04:23,650 --> 00:04:28,540 know as two in decimal which store it in binary as 0, 1, 0. 89 00:04:28,540 --> 00:04:32,800 Because that's 4 times 0 plus 2 times 1 plus time 1 times 0, 90 00:04:32,800 --> 00:04:35,380 which, of course, is going to give me the number 2. 91 00:04:35,380 --> 00:04:36,195 What about 3? 92 00:04:36,195 --> 00:04:38,050 Well, in the world of computers, if we again 93 00:04:38,050 --> 00:04:40,210 have our one's place two's place and four's place, 94 00:04:40,210 --> 00:04:43,966 how do I now arrange my zeros and ones to give me the number we know as 3? 95 00:04:43,966 --> 00:04:45,340 Well, let's see I don't need a 4. 96 00:04:45,340 --> 00:04:46,256 That would be too big. 97 00:04:46,256 --> 00:04:48,340 I do need a 2, and I do need a 1. 98 00:04:48,340 --> 00:04:49,900 And that is now going to give me 3. 99 00:04:49,900 --> 00:04:56,110 Because 2 times 1, 1 times 1 is 2, 1 times 1 is 1, 2 plus 1 is 3. 100 00:04:56,110 --> 00:04:57,399 Now what about 4? 101 00:04:57,399 --> 00:04:58,690 How do I count as high as four? 102 00:04:58,690 --> 00:05:02,630 Well, it's even easier, perhaps because we just need a single 1 in this case. 103 00:05:02,630 --> 00:05:05,016 We just need 1, 0, 0. 104 00:05:05,016 --> 00:05:06,890 Because now I have one 1 in the four's place. 105 00:05:06,890 --> 00:05:07,960 And now let's skip ahead. 106 00:05:07,960 --> 00:05:13,450 Suppose I want to count up as high as, let's say, 7? 107 00:05:13,450 --> 00:05:14,780 What do I do? 108 00:05:14,780 --> 00:05:17,280 Well, 7, let me take a byte out of that. 109 00:05:17,280 --> 00:05:18,490 So this gives me 4. 110 00:05:18,490 --> 00:05:21,040 Let me take a two, that gives me 4 plus 2, that's 6. 111 00:05:21,040 --> 00:05:22,930 Let me give myself another 1. 112 00:05:22,930 --> 00:05:27,160 1, 1, 1, in binary, equals 7. 113 00:05:27,160 --> 00:05:28,990 Now what about a number like 8? 114 00:05:28,990 --> 00:05:33,810 I can't seem to count as high as 8 unless I give myself another bit. 115 00:05:33,810 --> 00:05:36,190 But that's OK because, just as in the human world, 116 00:05:36,190 --> 00:05:38,773 if you have not a three-digit number, but a four-digit number, 117 00:05:38,773 --> 00:05:40,000 you simply add another place. 118 00:05:40,000 --> 00:05:43,456 So it might be the ones column, the tens, the hundreds, the thousands. 119 00:05:43,456 --> 00:05:46,330 In this case, though, it's going to be the ones, the twos, the fours, 120 00:05:46,330 --> 00:05:47,020 and the eights. 121 00:05:47,020 --> 00:05:49,150 And so if we want to count as high as 8 in binary, 122 00:05:49,150 --> 00:05:54,160 we might do 1, 0, 0, 0, which, of course, gives me 8 times 1. 123 00:05:54,160 --> 00:05:55,750 And then everything else is 0. 124 00:05:55,750 --> 00:05:58,220 So that gives me the number 8. 125 00:05:58,220 --> 00:06:01,780 So even though computers only speak 0s and 1s 126 00:06:01,780 --> 00:06:03,880 and only understand the so-called binary system, 127 00:06:03,880 --> 00:06:06,760 they can still count as high as we humans can. 128 00:06:06,760 --> 00:06:10,630 And they fundamentally do it, really, in the same way. 129 00:06:10,630 --> 00:06:13,510 It's just that they have a smaller vocabulary. 130 00:06:13,510 --> 00:06:15,600 But why do they have a smaller vocabulary, 131 00:06:15,600 --> 00:06:17,100 especially when they can do so much? 132 00:06:17,100 --> 00:06:19,450 Well, it turns out that, in the physical world, 133 00:06:19,450 --> 00:06:22,701 it's just convenient to be able to represent only two states instead 134 00:06:22,701 --> 00:06:23,200 of 10. 135 00:06:23,200 --> 00:06:25,630 And by states, I mean digits, in this case. 136 00:06:25,630 --> 00:06:27,670 It's a lot easier in the human world, not 137 00:06:27,670 --> 00:06:31,450 to represent 10 possible values 0 or 9, but just two-- 138 00:06:31,450 --> 00:06:32,375 0 and 1. 139 00:06:32,375 --> 00:06:34,750 And we could have called those digits anything we wanted, 140 00:06:34,750 --> 00:06:36,999 but we humans just standardized our numbers like that. 141 00:06:36,999 --> 00:06:43,420 But 0 and 1 is nice because if you think of one of these binary digits or bits 142 00:06:43,420 --> 00:06:46,390 as just being a light bulb-- it's either off or on. 143 00:06:46,390 --> 00:06:49,380 You can think of a 0 as a light bulb being off 144 00:06:49,380 --> 00:06:52,270 and a one as being a light bulb being on. 145 00:06:52,270 --> 00:06:55,750 And light bulbs, of course, in our human world just need electricity to run. 146 00:06:55,750 --> 00:06:59,320 And so, if we somehow get electricity into our computer laptop, desktop, 147 00:06:59,320 --> 00:07:03,500 or whatnot coming from the power outlet in the wall or some battery, 148 00:07:03,500 --> 00:07:06,310 well, that would seem to be sufficient input in order 149 00:07:06,310 --> 00:07:11,260 to turn a light bulb on or off, to turn a switch, really, on or off. 150 00:07:11,260 --> 00:07:14,770 And indeed, that's what's inside of our computers-- transistors, 151 00:07:14,770 --> 00:07:16,060 otherwise known as switches. 152 00:07:16,060 --> 00:07:19,270 And these transistors, which now number in the billions in the most 153 00:07:19,270 --> 00:07:22,720 modern of computers are tiny, tiny, tiny little light switches, 154 00:07:22,720 --> 00:07:28,810 if you will, that, if turned on, allow us to store 1s, if turned off, 155 00:07:28,810 --> 00:07:31,030 allow us to store 0s. 156 00:07:31,030 --> 00:07:33,760 And using those many, many, many transistors, 157 00:07:33,760 --> 00:07:37,270 can we store values, can we store data, can we compute, 158 00:07:37,270 --> 00:07:41,380 and can we actually do everything we can today with our modern computers. 159 00:07:41,380 --> 00:07:45,970 Let's make this more real and try out some actual light bulbs. 160 00:07:45,970 --> 00:07:48,880 So here are some light bulbs clamped into these desk lamps. 161 00:07:48,880 --> 00:07:51,520 And suppose now that I have these light bulbs here 162 00:07:51,520 --> 00:07:53,530 to represent bits or binary digits. 163 00:07:53,530 --> 00:07:56,710 So each of these light bulbs can represent a 0 if it's off 164 00:07:56,710 --> 00:07:58,310 or a 1 if it's on. 165 00:07:58,310 --> 00:08:00,880 And if we think about the same system that computers use, 166 00:08:00,880 --> 00:08:04,330 let's think of this bulb here as being the one's place, this bulb here 167 00:08:04,330 --> 00:08:08,260 as being the two's place and this bulb here as being the four's place. 168 00:08:08,260 --> 00:08:10,300 So what number am I currently representing 169 00:08:10,300 --> 00:08:12,520 if all of these light bulbs are off? 170 00:08:12,520 --> 00:08:14,575 Well, that's like having 0, 0, 0. 171 00:08:14,575 --> 00:08:17,950 Since they're all off, so that's the number we humans know in decimal, 172 00:08:17,950 --> 00:08:20,440 dec meaning 10, as 0. 173 00:08:20,440 --> 00:08:23,539 What about if I turn on just this one light bulb here? 174 00:08:23,539 --> 00:08:24,580 What does that represent? 175 00:08:24,580 --> 00:08:27,930 This, again, is the one's place, the two's place, and the four's place. 176 00:08:27,930 --> 00:08:30,820 So this, of course, represents the number we know as 1. 177 00:08:30,820 --> 00:08:34,720 Now, if I go ahead and simultaneously switch these, 178 00:08:34,720 --> 00:08:37,799 this is still the one's place, the two's place, and the four's place. 179 00:08:37,799 --> 00:08:38,634 So what is this? 180 00:08:38,634 --> 00:08:40,960 This, now, is the number we know as 2. 181 00:08:40,960 --> 00:08:42,610 How do I count as high as 3? 182 00:08:42,610 --> 00:08:44,470 I don't want to keep going down the line. 183 00:08:44,470 --> 00:08:49,960 Instead, I want to turn this 1 back on because that means I get a 1 plus a 2. 184 00:08:49,960 --> 00:08:54,180 I don't need the 4, which is great, because now I have 3. 185 00:08:54,180 --> 00:08:55,350 How do I get to 4 then? 186 00:08:55,350 --> 00:08:59,250 Well, let me turn both of these off, turn this one on, and now, of course, 187 00:08:59,250 --> 00:09:00,420 this is the four's place. 188 00:09:00,420 --> 00:09:01,620 So this is a 4. 189 00:09:01,620 --> 00:09:05,250 If I turn this one back on, now we're up to a four's place and a one's place, 190 00:09:05,250 --> 00:09:06,630 so that gives me 5. 191 00:09:06,630 --> 00:09:12,420 If I turn this off, this on, that gives me a 4 plus a 2, or a 6. 192 00:09:12,420 --> 00:09:16,260 And finally, if that turns on, I have now a 7. 193 00:09:16,260 --> 00:09:18,540 Unfortunately, I can't count as high as 8 194 00:09:18,540 --> 00:09:20,790 unless I go get myself another desk lamp, 195 00:09:20,790 --> 00:09:23,416 but for that we just need another bit. 196 00:09:23,416 --> 00:09:27,330 But this is all very fine and good, but all I can represent thus far, it seems, 197 00:09:27,330 --> 00:09:29,010 are numbers. 198 00:09:29,010 --> 00:09:33,240 How, though, do I represent letters of the actual alphabet, A through Z? 199 00:09:33,240 --> 00:09:35,820 How do I represent words or paragraphs, let 200 00:09:35,820 --> 00:09:39,529 alone emails, and any number of other features that computers today support? 201 00:09:39,529 --> 00:09:41,820 Well, for that, we're going to need to make a decision. 202 00:09:41,820 --> 00:09:44,250 We're going to need to decide what patterns of bits 203 00:09:44,250 --> 00:09:48,990 to use to represent those higher level notions like letters 204 00:09:48,990 --> 00:09:50,610 words and paragraphs. 205 00:09:50,610 --> 00:09:52,050 So for that, I've got an idea. 206 00:09:52,050 --> 00:09:55,650 207 00:09:55,650 --> 00:09:59,972 So at the end of the day, all computers can store is, indeed, 0s and 1s. 208 00:09:59,972 --> 00:10:01,680 And from those zeros and ones, of course, 209 00:10:01,680 --> 00:10:05,950 can we count higher so long as we have a mapping from binary to the numbers 210 00:10:05,950 --> 00:10:06,900 we know as decimal. 211 00:10:06,900 --> 00:10:08,990 But, of course, we want our computers to do more. 212 00:10:08,990 --> 00:10:12,656 We want to be able to express words and even other types of data. 213 00:10:12,656 --> 00:10:13,530 So how do we do that? 214 00:10:13,530 --> 00:10:16,950 Well, we need to come up with a standardization, a mapping, 215 00:10:16,950 --> 00:10:20,610 from 0s and 1s, or really just numbers, to the letters that we want. 216 00:10:20,610 --> 00:10:24,394 And it turns out, that some years ago what humans decided to do was this. 217 00:10:24,394 --> 00:10:26,810 Now, at first glance, this might be a little overwhelming. 218 00:10:26,810 --> 00:10:29,505 This is just a screenshot of a chart from asciichart.com. 219 00:10:29,505 --> 00:10:34,260 An ASCII chart is a chart of ASCII characters, American Standard 220 00:10:34,260 --> 00:10:36,270 Code for Information Interchange. 221 00:10:36,270 --> 00:10:40,410 And this is simply a mapping from decimal numbers to letters. 222 00:10:40,410 --> 00:10:42,150 And so on let's notice a few of these. 223 00:10:42,150 --> 00:10:48,690 Notice here that 65 apparently maps to A, 66 maps to B, 67 maps to C, 224 00:10:48,690 --> 00:10:49,410 and so forth. 225 00:10:49,410 --> 00:10:55,320 Meanwhile, 97 maps to lowercase a, 98 to lowercase b, 99 to lowercase c, 226 00:10:55,320 --> 00:10:56,140 and so forth. 227 00:10:56,140 --> 00:10:58,590 And there's also mappings from punctuation symbols 228 00:10:58,590 --> 00:11:02,160 to all the letters of the alphabet that you may know. 229 00:11:02,160 --> 00:11:04,180 So why is this significant? 230 00:11:04,180 --> 00:11:08,180 Well, it turns out that even though computers only store 0s and 1s, 231 00:11:08,180 --> 00:11:09,930 we, of course, use them in different ways. 232 00:11:09,930 --> 00:11:13,860 We have programs like Notepad on PCs, or TextEdit on Mac OS, 233 00:11:13,860 --> 00:11:17,640 or Microsoft Word on both platforms, or Google spreadsheets, or Google Docs, 234 00:11:17,640 --> 00:11:18,370 or the like. 235 00:11:18,370 --> 00:11:20,161 And so we have all these different programs 236 00:11:20,161 --> 00:11:22,960 that is designed to do one thing or the other. 237 00:11:22,960 --> 00:11:27,060 And so those programs essentially decide, in their own context, 238 00:11:27,060 --> 00:11:31,380 whether to display patterns of bits as numbers or as letters 239 00:11:31,380 --> 00:11:33,120 or, in turn, words and paragraphs. 240 00:11:33,120 --> 00:11:35,580 So it's entirely context-dependent. 241 00:11:35,580 --> 00:11:38,610 At the end of the day, all the computer is storing is 0s and 1s, 242 00:11:38,610 --> 00:11:42,240 but it's up to the program to interpret those 0s and 1s in a certain way. 243 00:11:42,240 --> 00:11:46,650 And so, if a program like Microsoft Word or Google Docs 244 00:11:46,650 --> 00:11:54,580 sees a pattern of bits in a file that represents the decimal number 65-- 245 00:11:54,580 --> 00:11:57,919 it's still pattern of 0s and 1s expressed in binary, 246 00:11:57,919 --> 00:12:00,460 but of course, we've seen how we can convert that to decimal. 247 00:12:00,460 --> 00:12:03,300 So if a computer is ultimately storing a pattern of 0s and 1s 248 00:12:03,300 --> 00:12:06,900 that represents the decimal number 65, the computer, 249 00:12:06,900 --> 00:12:10,130 in this case Microsoft Word, or Google Docs, and the program running there, 250 00:12:10,130 --> 00:12:13,650 is going to interpret that pattern, not as the number 65, 251 00:12:13,650 --> 00:12:18,240 and not as a whole bunch of 0s and 1s alone, but as the capital letter A. 252 00:12:18,240 --> 00:12:19,990 And that's what you'll see on your screen. 253 00:12:19,990 --> 00:12:24,022 If it, instead, sees a pattern of bits that represents the decimal number 66, 254 00:12:24,022 --> 00:12:25,980 Microsoft Word or Google Docs is going to show, 255 00:12:25,980 --> 00:12:28,530 instead, the capitol letter B. If the pattern of bits 256 00:12:28,530 --> 00:12:31,680 instead represents the decimal number 97, 257 00:12:31,680 --> 00:12:35,490 that program is going to display the lowercase letter a or any number 258 00:12:35,490 --> 00:12:37,630 of other letters from the alphabet. 259 00:12:37,630 --> 00:12:41,730 And so we just had to decide in advance what mapping to use, 260 00:12:41,730 --> 00:12:44,850 what code to use that maps numbers to letters. 261 00:12:44,850 --> 00:12:47,370 And in fact, you'll notice that quite a few characters 262 00:12:47,370 --> 00:12:48,890 are absent from the screen here. 263 00:12:48,890 --> 00:12:52,140 In fact, if you speak some language and write some language other than English 264 00:12:52,140 --> 00:12:53,931 there might be some characters that you can 265 00:12:53,931 --> 00:12:56,890 express with just this range of values. 266 00:12:56,890 --> 00:13:00,300 In fact ASCII originally only used 7 bits total. 267 00:13:00,300 --> 00:13:04,350 Or if you round up, 8 bits total, for what's called the extended ASCII. 268 00:13:04,350 --> 00:13:09,930 And it turns out, that's not nearly enough patterns of bits, 256 maximally, 269 00:13:09,930 --> 00:13:12,240 that you can use to express characters that you might 270 00:13:12,240 --> 00:13:15,900 see in certain Asian languages or symbols that just simply are not 271 00:13:15,900 --> 00:13:17,880 depicted even yet on the screen here. 272 00:13:17,880 --> 00:13:19,770 So there are other systems, not just ASCII. 273 00:13:19,770 --> 00:13:23,400 Something called Unicode, for instance, is a superset of what you see here. 274 00:13:23,400 --> 00:13:26,190 And that actually allows us to express any number of characters 275 00:13:26,190 --> 00:13:29,550 from English and Asian languages and beyond and, in fact, even 276 00:13:29,550 --> 00:13:32,739 things like the emoji characters-- the smiley faces, 277 00:13:32,739 --> 00:13:35,280 and other such characters that you might now use increasingly 278 00:13:35,280 --> 00:13:37,170 on your phone, your desktop, or laptop. 279 00:13:37,170 --> 00:13:40,287 Those two are expressed ultimately as just patterns of bits. 280 00:13:40,287 --> 00:13:42,120 And the world, for the most part, has simply 281 00:13:42,120 --> 00:13:44,820 standardized on what pattern of bits represents 282 00:13:44,820 --> 00:13:48,450 a happy face, what pattern of bits represents a sad face, 283 00:13:48,450 --> 00:13:51,750 and beyond, in that system there is Unicode. 284 00:13:51,750 --> 00:13:53,740 So let's take an example. 285 00:13:53,740 --> 00:13:57,450 Suppose that you see this pattern of bits somewhere in a file. 286 00:13:57,450 --> 00:14:00,840 And you, in this context, say are Microsoft Word, or Google Docs, 287 00:14:00,840 --> 00:14:04,560 or some program designed to display, not numbers like a calculator, 288 00:14:04,560 --> 00:14:08,310 but words and letters like a word processor or a text editor. 289 00:14:08,310 --> 00:14:10,140 Well, what is this pattern of bits? 290 00:14:10,140 --> 00:14:12,000 Well, we haven't seen this many bits before, 291 00:14:12,000 --> 00:14:16,230 but it looks to be like two patterns of eight. 292 00:14:16,230 --> 00:14:20,580 And in fact, it turns out that anytime you have eight bits here or eight bits 293 00:14:20,580 --> 00:14:24,810 here, humans generally refer to this as a byte, B-Y-T-E. 294 00:14:24,810 --> 00:14:26,730 So a byte is just eight bits. 295 00:14:26,730 --> 00:14:28,920 And it's a slightly more useful measure because it's 296 00:14:28,920 --> 00:14:32,980 a lot bigger than a single bit, which can, of course, only represent 0 or 1. 297 00:14:32,980 --> 00:14:35,260 A byte can actually count higher. 298 00:14:35,260 --> 00:14:38,640 So what are the columns here if we look only at this number at left? 299 00:14:38,640 --> 00:14:48,000 This is my 1's place, 2's, 4's, 8's, 16's, 32's, and 64, and then 128. 300 00:14:48,030 --> 00:14:53,520 So 64 plus 8, if I do that arithmetic, that gives me 72. 301 00:14:53,550 --> 00:14:56,160 Now let's consider the pattern of bits on the right. 302 00:14:56,160 --> 00:15:05,250 Again, my 1's place, 2's place, 4's 8's, 16's, 32, 64, 128. 303 00:15:05,250 --> 00:15:08,370 Now notice, these patterns are actually almost identical. 304 00:15:08,370 --> 00:15:12,340 We've got a 1 in the 64's place, we've got a 1 in the 8's place, 305 00:15:12,340 --> 00:15:15,690 but we've also got an extra one in the 1's place. 306 00:15:15,690 --> 00:15:21,750 So if this was 72, and this pattern is identical except for this last bit 307 00:15:21,750 --> 00:15:27,842 here, which adds 1, this must be 72 followed by 73. 308 00:15:27,842 --> 00:15:29,550 And I've put a space here, visually, just 309 00:15:29,550 --> 00:15:32,216 to separate the fact that these are, indeed, two separate bytes. 310 00:15:32,216 --> 00:15:35,550 And I claim now that, yes, while you could interpret these 311 00:15:35,550 --> 00:15:42,510 as two decimal digits, 72 and 73, it turns out, per the ASCII system, 312 00:15:42,510 --> 00:15:46,890 we could map 72 and 73 to alphabetical letters. 313 00:15:46,890 --> 00:15:48,150 What might those letters be? 314 00:15:48,150 --> 00:15:51,780 Well, if we consider our chart again, 72 apparently 315 00:15:51,780 --> 00:15:55,290 gives us a capital H. 73 gives us the capital I. 316 00:15:55,290 --> 00:15:59,700 And, voila, 72 followed by 73 in a computer's memory, apparently, 317 00:15:59,700 --> 00:16:02,700 is how a computer would express HI. 318 00:16:02,700 --> 00:16:07,050 And of course, if we used more bytes, and therefore more bits, and therefore 319 00:16:07,050 --> 00:16:11,550 more numbers, we could represent even larger words than just H I, or HI. 320 00:16:11,550 --> 00:16:14,710 But that's exactly how a computer, underneath the hood so to speak, 321 00:16:14,710 --> 00:16:17,700 would store a word like HI. 322 00:16:17,700 --> 00:16:21,000 Now what is indeed using these patterns of bits? 323 00:16:21,000 --> 00:16:24,240 And what is a computer actually doing at the end of the day? 324 00:16:24,240 --> 00:16:28,200 Well, for that, we need to take a look under the hood, so to speak. 325 00:16:28,200 --> 00:16:31,470 This is what Intel inside means. 326 00:16:31,470 --> 00:16:37,680 If your Mac or your PC comes with an Intel Inside, 327 00:16:37,680 --> 00:16:41,360 as goes the marketing slogan, that means that your computer has inside of it 328 00:16:41,360 --> 00:16:46,216 a CPU, a Central Processing Unit that looks a little something like this. 329 00:16:46,216 --> 00:16:47,340 It's a pretty small device. 330 00:16:47,340 --> 00:16:48,705 It's not quite as big as this. 331 00:16:48,705 --> 00:16:50,159 This, of course, is not to scale. 332 00:16:50,159 --> 00:16:52,619 It wouldn't fit in your actual laptop or desktop. 333 00:16:52,619 --> 00:16:54,000 But what you see is two sides. 334 00:16:54,000 --> 00:16:56,444 This is just a mental case and a nice big logo there. 335 00:16:56,444 --> 00:16:58,860 And then, if you flip this around, you see the other side, 336 00:16:58,860 --> 00:17:01,740 which generally has a whole bunch of golden pins 337 00:17:01,740 --> 00:17:05,879 that actually interconnect to a device inside of the computer. 338 00:17:05,879 --> 00:17:08,010 And now what is that device? 339 00:17:08,010 --> 00:17:11,419 Well, that device, we'll soon see, is something called the motherboard. 340 00:17:11,419 --> 00:17:14,490 A motherboard is a circuit board, so a big piece 341 00:17:14,490 --> 00:17:17,910 of silicon or plastic-like material that has 342 00:17:17,910 --> 00:17:20,640 a lot of lines running back and forth on it, 343 00:17:20,640 --> 00:17:23,880 and often has sockets, essentially, a bunch of tiny little holes 344 00:17:23,880 --> 00:17:28,890 into which devices like this fit so that you can put this inside of a computer 345 00:17:28,890 --> 00:17:31,110 and actually have it clamped down on something. 346 00:17:31,110 --> 00:17:32,970 Now what does it mean to be a CPU? 347 00:17:32,970 --> 00:17:34,846 Well, the CPU is the brains of your computer. 348 00:17:34,846 --> 00:17:36,553 It's the thing in your computer that does 349 00:17:36,553 --> 00:17:38,100 all of the work, all of the thinking. 350 00:17:38,100 --> 00:17:40,230 Now what kind of thinking does a computer need to do? 351 00:17:40,230 --> 00:17:41,850 Well, if you're feeding it all of these numbers, 352 00:17:41,850 --> 00:17:43,710 and you're feeding it all of these letters, 353 00:17:43,710 --> 00:17:46,500 you want to maybe perform math on those numbers. 354 00:17:46,500 --> 00:17:49,096 You might want to display those letters on the screen. 355 00:17:49,096 --> 00:17:50,970 You might want to add or delete those letters 356 00:17:50,970 --> 00:17:53,640 if the user is using a word processor and typing new characters 357 00:17:53,640 --> 00:17:54,570 or hitting delete. 358 00:17:54,570 --> 00:17:58,320 And so a computer needs to do all of that thinking and work for the human. 359 00:17:58,320 --> 00:18:01,740 And the peace inside of the computer that does most of that work 360 00:18:01,740 --> 00:18:05,520 is, indeed, this device here called the CPU. 361 00:18:05,520 --> 00:18:10,020 Now, it turns out, that CPUs today are actually getting pretty fancy. 362 00:18:10,020 --> 00:18:14,990 And inside of a CPU, typically, is one or more cores, so to speak. 363 00:18:14,990 --> 00:18:17,640 And a core is really what's doing the work. 364 00:18:17,640 --> 00:18:21,090 And it is the device inside of this device that actually 365 00:18:21,090 --> 00:18:24,060 can do addition, and subtraction, and multiplication, and division, 366 00:18:24,060 --> 00:18:27,030 and other operations still loading information from memory, 367 00:18:27,030 --> 00:18:28,770 saving information to memory. 368 00:18:28,770 --> 00:18:33,570 And so a CPU like this might have one, or two, or four or more cores, 369 00:18:33,570 --> 00:18:38,110 which means it can do one, or two, or four or more things at a time. 370 00:18:38,110 --> 00:18:40,560 And that's great because, these days on my Mac or my PC, 371 00:18:40,560 --> 00:18:42,420 I might double-click a whole bunch of icons. 372 00:18:42,420 --> 00:18:43,980 I might be running multiple programs. 373 00:18:43,980 --> 00:18:45,720 I might be chatting with a friend over here. 374 00:18:45,720 --> 00:18:47,553 I might be working on my homework over here. 375 00:18:47,553 --> 00:18:50,940 And so I might have a lot of programs and a lot of files open simultaneously. 376 00:18:50,940 --> 00:18:55,650 And thanks to multiple cores inside of a CPU, can each of those programs 377 00:18:55,650 --> 00:18:57,564 continue running in parallel. 378 00:18:57,564 --> 00:18:59,480 Maybe one is printing something to my printer. 379 00:18:59,480 --> 00:19:01,380 Or maybe one is playing back a video. 380 00:19:01,380 --> 00:19:03,090 Maybe one is spell-checking a file. 381 00:19:03,090 --> 00:19:07,480 Any number of operations can literally be happening simultaneously. 382 00:19:07,480 --> 00:19:10,620 Now moreover, it turns out that the fanciest of use today, 383 00:19:10,620 --> 00:19:14,250 from Intel especially, also support something called hyperthreading, 384 00:19:14,250 --> 00:19:17,040 which means you might just have one CPU or one core, 385 00:19:17,040 --> 00:19:21,270 but thanks to some technology built into the CPU itself, 386 00:19:21,270 --> 00:19:24,960 it will present itself to the computer, to the operating system, 387 00:19:24,960 --> 00:19:27,900 Mac OS or Windows-- more on those in a bit-- 388 00:19:27,900 --> 00:19:31,200 as though it's actually two CPUs or two cores. 389 00:19:31,200 --> 00:19:35,100 And so, thanks to technology, can your computer actually 390 00:19:35,100 --> 00:19:38,290 think it has even more computational power than it actually has, 391 00:19:38,290 --> 00:19:41,170 thereby allowing it to take advantage of downtime 392 00:19:41,170 --> 00:19:44,500 or slow running programs that might still allow you 393 00:19:44,500 --> 00:19:47,290 to run multiple things simultaneously. 394 00:19:47,290 --> 00:19:49,690 But we'll come back to that in just a bit. 395 00:19:49,690 --> 00:19:54,010 Now, not all devices have just a CPU connected to a motherboard. 396 00:19:54,010 --> 00:20:00,310 Some devices, instead, have a CPU and more all interconnected all at once. 397 00:20:00,310 --> 00:20:02,830 And these things are generally known as systems on a chip. 398 00:20:02,830 --> 00:20:06,790 And they're especially popular in things like tablets or iPads these days, 399 00:20:06,790 --> 00:20:10,720 game consoles like Xboxes or even things like the Raspberry Pi, 400 00:20:10,720 --> 00:20:14,170 which is a very small computer that looks pretty much like this. 401 00:20:14,170 --> 00:20:17,080 Also not to scale, this thing could fit in the palm of my hand. 402 00:20:17,080 --> 00:20:20,530 And this has, not only one of these silicon circuit boards-- 403 00:20:20,530 --> 00:20:24,520 generally green, and you'll see there's very fine lines or traces that 404 00:20:24,520 --> 00:20:26,680 interconnect all of the chips and technology 405 00:20:26,680 --> 00:20:28,870 that's plugged into this thing-- and it also has, 406 00:20:28,870 --> 00:20:30,350 well, first and foremost, no case. 407 00:20:30,350 --> 00:20:33,224 There's no pretty plastic case that protects all of these components. 408 00:20:33,224 --> 00:20:34,990 It really is just a raw piece of hardware 409 00:20:34,990 --> 00:20:39,670 that computer technophiles like to use to build their own machines 410 00:20:39,670 --> 00:20:41,530 and programs. 411 00:20:41,530 --> 00:20:43,270 But it has a whole bunch of ports-- 412 00:20:43,270 --> 00:20:45,490 as we'll return to in a bit-- a whole bunch of places 413 00:20:45,490 --> 00:20:47,750 you can connect other devices. 414 00:20:47,750 --> 00:20:49,780 But these systems on a chip all come together. 415 00:20:49,780 --> 00:20:54,190 And they do many things beyond just the CPU's task alone. 416 00:20:54,190 --> 00:20:55,990 But what else is inside of your computer? 417 00:20:55,990 --> 00:20:57,700 Well, the CPU is the brain. 418 00:20:57,700 --> 00:21:01,370 And the CPU on a system on a chip is thereto the brain. 419 00:21:01,370 --> 00:21:04,209 But there's other components necessary inside of a computer 420 00:21:04,209 --> 00:21:05,250 so we can do actual work. 421 00:21:05,250 --> 00:21:09,190 And one of those things is called memory or random access memory. 422 00:21:09,190 --> 00:21:13,135 And random access memory looks, physically, like this. 423 00:21:13,135 --> 00:21:19,150 This is a chip that you might slide into a little slot inside of your computer 424 00:21:19,150 --> 00:21:23,050 specifically on the so-called motherboard, again, a big greenish 425 00:21:23,050 --> 00:21:25,779 board into which all of your computer's components connect. 426 00:21:25,779 --> 00:21:28,570 And there's usually a little divot here, a little bump to make sure 427 00:21:28,570 --> 00:21:31,611 you put it in the right way-- instead this way, instead of, for instance, 428 00:21:31,611 --> 00:21:32,260 that way. 429 00:21:32,260 --> 00:21:35,440 And then on this green circuit board are all these various chips 430 00:21:35,440 --> 00:21:37,510 that actually store your data. 431 00:21:37,510 --> 00:21:42,700 Specifically, they store your data in a volatile way, only when the power is 432 00:21:42,700 --> 00:21:45,190 on, when your laptop has battery and is running 433 00:21:45,190 --> 00:21:47,740 or when your laptop is plugged in and is running. 434 00:21:47,740 --> 00:21:50,260 Which is to say, when you double-click an icon on the screen 435 00:21:50,260 --> 00:21:54,220 or run some program, open some file, those files 436 00:21:54,220 --> 00:21:59,050 are loaded into the little black chips that you see on this stick here. 437 00:21:59,050 --> 00:22:01,750 They're loaded into RAM or Random Access Memory. 438 00:22:01,750 --> 00:22:03,370 And this memory is pretty fast. 439 00:22:03,370 --> 00:22:05,920 And it is where those files and programs live, 440 00:22:05,920 --> 00:22:09,250 so long as you are using them at a given moment in time. 441 00:22:09,250 --> 00:22:12,370 Now other devices have slightly different looking sticks of RAM. 442 00:22:12,370 --> 00:22:14,500 This is a smaller stick here that's actually 443 00:22:14,500 --> 00:22:18,550 found, typically, in laptops or certain desktop models, but it's the same idea. 444 00:22:18,550 --> 00:22:20,510 It's simply a different form factor. 445 00:22:20,510 --> 00:22:23,020 Now you can actually see in your Mac or PC 446 00:22:23,020 --> 00:22:25,169 sometimes exactly how much RAM you have, especially 447 00:22:25,169 --> 00:22:27,460 if you bought the computer without knowing this concept 448 00:22:27,460 --> 00:22:29,930 or were given the computer and didn't think to ask. 449 00:22:29,930 --> 00:22:33,910 In fact, on Windows, if you open up the so-called Task Manager 450 00:22:33,910 --> 00:22:38,110 and look at the CPU tab, you might see a little something like this. 451 00:22:38,110 --> 00:22:41,380 You'll see one, a nice little chart that shows you what your CPU has 452 00:22:41,380 --> 00:22:43,120 been doing over the past few seconds. 453 00:22:43,120 --> 00:22:44,950 And the higher these peaks are, the busier it was. 454 00:22:44,950 --> 00:22:47,033 Maybe you double-clicked an icon or played a video 455 00:22:47,033 --> 00:22:49,570 or sent a really big email or something like that. 456 00:22:49,570 --> 00:22:52,990 But more interesting, down here, is the speed of your CPU. 457 00:22:52,990 --> 00:22:55,600 This one is 1.9 for gigahertz. 458 00:22:55,600 --> 00:22:59,800 And a gigahertz means 1 billion things per second. 459 00:22:59,800 --> 00:23:04,360 So a you that's 1.9 for gigahertz means that this computer, this CPU 460 00:23:04,360 --> 00:23:08,590 can do 1.94 billion things per second-- 461 00:23:08,590 --> 00:23:10,330 additions, subtractions, multiplications, 462 00:23:10,330 --> 00:23:13,040 printing to the screen, any number of other things. 463 00:23:13,040 --> 00:23:17,500 But if we look, odds are this is marketed, frankly, as 2 gigahertz, 464 00:23:17,500 --> 00:23:20,020 and maybe it has burst technology whereby it can actually 465 00:23:20,020 --> 00:23:23,140 go even a little faster, maximum speed 2.81 466 00:23:23,140 --> 00:23:28,242 gigahertz by maybe using a little more energy for some amount of time 467 00:23:28,242 --> 00:23:29,950 and therefore generating a bit more heat. 468 00:23:29,950 --> 00:23:33,730 But you'll see that there's only one socket in the computer from which I 469 00:23:33,730 --> 00:23:36,560 took this screenshot from Windows, which means there's one CPU. 470 00:23:36,560 --> 00:23:40,720 But that CPU has two cores, which means that the computer can do literally 471 00:23:40,720 --> 00:23:44,987 two things at once because it has really two brains inside of that device 472 00:23:44,987 --> 00:23:46,570 that we saw a picture of a moment ago. 473 00:23:46,570 --> 00:23:48,880 But logically, it actually seems four. 474 00:23:48,880 --> 00:23:54,160 So this particular windows computer has a CPU with two cores, each of which 475 00:23:54,160 --> 00:23:56,650 supports that technology called hyperthreading, which 476 00:23:56,650 --> 00:24:01,120 means that each of those cores will present itself to the Windows operating 477 00:24:01,120 --> 00:24:02,590 system as though it's two. 478 00:24:02,590 --> 00:24:05,770 Which is to say each core will do two things simultaneously, 479 00:24:05,770 --> 00:24:10,120 thereby giving me four logical processors or, really, the ability 480 00:24:10,120 --> 00:24:12,410 to do 4 total things at once. 481 00:24:12,410 --> 00:24:15,220 So perhaps lower level detail than is perhaps germane, 482 00:24:15,220 --> 00:24:18,550 but these are the kinds of things that you end up paying for in a store 483 00:24:18,550 --> 00:24:20,444 or when you buy a computer online. 484 00:24:20,444 --> 00:24:23,110 This is what distinguishes a less expensive computer from a more 485 00:24:23,110 --> 00:24:27,400 expensive computer is just how fast the CPU or CPUs are 486 00:24:27,400 --> 00:24:30,460 and just how many cores the CPU has and, therefore, 487 00:24:30,460 --> 00:24:34,480 just how much work you can get done at a given moment in time 488 00:24:34,480 --> 00:24:36,930 or just how quickly you can work more generally. 489 00:24:36,930 --> 00:24:40,100 Now, in a Mac, if you open up your System Profiler, 490 00:24:40,100 --> 00:24:43,310 you'll see a different kind of interface, but similar information. 491 00:24:43,310 --> 00:24:45,560 This is taken here from a MacBook Pro. 492 00:24:45,560 --> 00:24:50,750 You can see that this CPU is 3.1 gigahertz, so faster, 493 00:24:50,750 --> 00:24:55,010 but it has one processor, total number of cores is two. 494 00:24:55,010 --> 00:24:59,240 And so, here, we see no mention of hyperthreading, which generally windows 495 00:24:59,240 --> 00:25:03,560 is a bit more detailed on, but this does mean that this CPU is pretty darn fast, 496 00:25:03,560 --> 00:25:05,990 3.1 billion things per second. 497 00:25:05,990 --> 00:25:10,970 And it actually has two cores, so it can do at least two things at once. 498 00:25:10,970 --> 00:25:11,570 All right. 499 00:25:11,570 --> 00:25:15,170 So that's my CPU, which does all the thinking and all of the work. 500 00:25:15,170 --> 00:25:18,620 That's RAM or random access memory where all of my data and programs 501 00:25:18,620 --> 00:25:21,690 are stored while I am using them. 502 00:25:21,690 --> 00:25:23,550 So what else do I need? 503 00:25:23,550 --> 00:25:27,200 Well, where are those programs and files stored when the power is not on 504 00:25:27,200 --> 00:25:31,800 or when my battery is dead or when my computer is not even plugged in. 505 00:25:31,800 --> 00:25:35,570 Now, odds are, if your computer is like mine, you don't lose all of your files 506 00:25:35,570 --> 00:25:37,880 and all of your programs just because your battery dies 507 00:25:37,880 --> 00:25:40,505 or you move a computer, and therefore, unplug it from the wall. 508 00:25:40,505 --> 00:25:42,320 It would not be a very useful device. 509 00:25:42,320 --> 00:25:46,850 Computers do have nonvolatile memory that sticks around 510 00:25:46,850 --> 00:25:49,910 even when the power is lost, but it uses a different technology 511 00:25:49,910 --> 00:25:51,350 than RAM for that. 512 00:25:51,350 --> 00:25:55,160 It tends to use a disk or a hard disk, as in this case. 513 00:25:55,160 --> 00:25:59,540 So this is a device that a PC desktop or Mac desktop might have inside of it. 514 00:25:59,540 --> 00:26:03,350 And it actually stores quite a bit more information than a stick of RAM. 515 00:26:03,350 --> 00:26:08,360 A stick of RAM might store one gigabyte, two gigabytes, maybe even 16 gigabytes. 516 00:26:08,360 --> 00:26:11,810 But a hard drive, as this thing is called, 517 00:26:11,810 --> 00:26:16,940 will actually store 256 gigabytes, or maybe 1,000 gigabytes, 518 00:26:16,940 --> 00:26:21,740 AKA a terabyte or even two terabytes or four terabytes, which 519 00:26:21,740 --> 00:26:25,292 is an order of magnitude more than our sticks of RAM. 520 00:26:25,292 --> 00:26:27,500 Inside of this device, though, meanwhile is something 521 00:26:27,500 --> 00:26:29,100 that feels kind of old school. 522 00:26:29,100 --> 00:26:32,900 It's actually one or more metal platters that literally 523 00:26:32,900 --> 00:26:35,630 physically spin around mechanically. 524 00:26:35,630 --> 00:26:38,610 And on those platters is your data actually stored. 525 00:26:38,610 --> 00:26:41,600 So in RAM, there were no moving parts. 526 00:26:41,600 --> 00:26:44,750 There is no fan, there's no motor, there's nothing to move back and forth. 527 00:26:44,750 --> 00:26:46,070 It's entirely electronic. 528 00:26:46,070 --> 00:26:48,350 It's all electrons at the end of the day. 529 00:26:48,350 --> 00:26:51,992 But a hard drive is a mechanical device that actually has one or more 530 00:26:51,992 --> 00:26:54,200 of these platters spinning and spinning and spinning. 531 00:26:54,200 --> 00:26:56,075 And that's what allows the computer to access 532 00:26:56,075 --> 00:26:57,740 different areas of those platters. 533 00:26:57,740 --> 00:27:00,650 And, in fact, you'll see one or more of these little reading heads, 534 00:27:00,650 --> 00:27:03,020 not unlike old school phonograph or record 535 00:27:03,020 --> 00:27:05,240 players that actually move back and forth 536 00:27:05,240 --> 00:27:08,060 and read the data from that device. 537 00:27:08,060 --> 00:27:11,810 And what's nice about this device is that it's nonvolatile. 538 00:27:11,810 --> 00:27:17,810 It uses tiny, tiny magnetic particles, little specks of magnetic particles, 539 00:27:17,810 --> 00:27:20,540 that, if you orient them this way might represent a 1. 540 00:27:20,540 --> 00:27:24,420 If you orient them this way it might represent a 0-- so north to south pole, 541 00:27:24,420 --> 00:27:27,350 south to north pole if you remember some of your electronics. 542 00:27:27,350 --> 00:27:31,310 But all that is to say is there's tiny, tiny, tiny little particles on here, 543 00:27:31,310 --> 00:27:35,330 billions or more perhaps, that, depending on their orientation up 544 00:27:35,330 --> 00:27:37,990 or down, represent a 1 or 0. 545 00:27:37,990 --> 00:27:39,740 And if you have enough of those particles, 546 00:27:39,740 --> 00:27:43,880 you can represent bytes or megabytes or gigabytes or terabytes 547 00:27:43,880 --> 00:27:46,040 or more or anything in between. 548 00:27:46,040 --> 00:27:50,300 And so you have the ability to store data this way 549 00:27:50,300 --> 00:27:52,400 or this way, even when the power is off. 550 00:27:52,400 --> 00:27:56,900 The power is used just to read the data or to write or change the data. 551 00:27:56,900 --> 00:28:00,770 It doesn't need to stick around to persist the data. 552 00:28:00,770 --> 00:28:03,410 So in fact, why don't we take a look at what this motor looks 553 00:28:03,410 --> 00:28:06,350 like when actually running. 554 00:28:06,350 --> 00:28:09,890 This is a short video from the Slow Mo Guys, which gives us 555 00:28:09,890 --> 00:28:12,770 a sense of what the hard drive looks like when its lid is indeed 556 00:28:12,770 --> 00:28:13,790 removed like that there. 557 00:28:13,790 --> 00:28:27,810 [VIDEO PLAYBACK] 558 00:28:27,810 --> 00:28:28,310 [END VIDEO] 559 00:28:28,310 --> 00:28:29,060 DAVID J. MALAN: Fascinating. 560 00:28:29,060 --> 00:28:29,750 I know. 561 00:28:29,750 --> 00:28:33,470 Well, now let's actually take the hood off of an actual hard drive, 562 00:28:33,470 --> 00:28:38,450 albeit via animation, and actually see and hear what it is that's going on. 563 00:28:38,450 --> 00:28:41,720 And in this depiction here, you'll see that the magnetic particles ultimately 564 00:28:41,720 --> 00:28:45,020 are represented as red-blue, or blue-red particles, which 565 00:28:45,020 --> 00:28:47,420 represent precisely those magnetic particles that 566 00:28:47,420 --> 00:28:49,410 represent your 0s and 1s. 567 00:28:49,410 --> 00:28:50,760 [VIDEO PLAYBACK] 568 00:28:50,760 --> 00:28:54,960 - The hard drive is where your PC stores most of its permanent data. 569 00:28:54,960 --> 00:28:57,900 To do that, the data travels from RAM along 570 00:28:57,900 --> 00:29:02,340 with software signals that tell the hard drive how to store that data. 571 00:29:02,340 --> 00:29:07,300 The hard drive circuits translate those signals into voltage fluctuations. 572 00:29:07,300 --> 00:29:10,470 These, in turn, control the hard drive's moving parts-- 573 00:29:10,470 --> 00:29:14,200 some of the few moving parts left in the modern computer. 574 00:29:14,200 --> 00:29:18,390 Some of the signals control a motor which spins metal-coated platters. 575 00:29:18,390 --> 00:29:21,700 Your data is actually stored on these platters. 576 00:29:21,700 --> 00:29:26,970 Other signals move the read-write heads to read or write data on the platters. 577 00:29:26,970 --> 00:29:30,840 This machinery is so precise that a human hair couldn't even 578 00:29:30,840 --> 00:29:33,590 pass between the heads and spinning platters. 579 00:29:33,590 --> 00:29:35,725 Yet, it all works at terrific speeds. 580 00:29:35,725 --> 00:29:36,615 [END VIDEO] 581 00:29:36,615 --> 00:29:38,490 DAVID J. MALAN: So where are those particles? 582 00:29:38,490 --> 00:29:41,850 Well, for that, we're going to have to zoom in even closer because they're not 583 00:29:41,850 --> 00:29:43,350 visible to the human eye. 584 00:29:43,350 --> 00:29:45,030 [VIDEO PLAYBACK] 585 00:29:45,030 --> 00:29:48,000 - Let's look at what we just saw in slow motion. 586 00:29:48,000 --> 00:29:51,510 When a brief pulse of electricity is sent to the read-write head, 587 00:29:51,510 --> 00:29:55,260 it flips on a tiny electromagnet for a fraction of a second. 588 00:29:55,260 --> 00:29:58,350 The magnet creates a field which changes the polarity 589 00:29:58,350 --> 00:30:00,840 of a tiny, tiny portion of the metal particles 590 00:30:00,840 --> 00:30:03,240 which coat each platter surface. 591 00:30:03,240 --> 00:30:06,240 A pattern series of these tiny charged up areas on the disk 592 00:30:06,240 --> 00:30:10,860 represents a single bit of data in the binary number system used by computers. 593 00:30:10,860 --> 00:30:13,770 Now, if the current is sent one way through the read-write head, 594 00:30:13,770 --> 00:30:16,211 the area is polarized in one direction. 595 00:30:16,211 --> 00:30:18,210 If the current is set in the opposite direction, 596 00:30:18,210 --> 00:30:20,310 the polarization is reversed. 597 00:30:20,310 --> 00:30:22,740 How do you get data off the hard disk? 598 00:30:22,740 --> 00:30:24,451 Just reverse the process. 599 00:30:24,451 --> 00:30:26,700 So it's the particles on the disk that get the current 600 00:30:26,700 --> 00:30:28,440 in the read-write head moving. 601 00:30:28,440 --> 00:30:30,870 Put together millions of these magnetized segments, 602 00:30:30,870 --> 00:30:32,490 and you've got a file. 603 00:30:32,490 --> 00:30:35,460 Now, the pieces of a single file may be scattered 604 00:30:35,460 --> 00:30:40,450 all over a drive's platters kind of like the mess of papers on your desk. 605 00:30:40,450 --> 00:30:43,860 So a special extra file keeps track of where everything is. 606 00:30:43,860 --> 00:30:45,790 Don't you wish you had something like that? 607 00:30:45,790 --> 00:30:48,199 [END VIDEO] 608 00:30:48,199 --> 00:30:50,490 DAVID J. MALAN: Now, anytime you have a physical device 609 00:30:50,490 --> 00:30:53,280 like this that's spinning all day long or for months 610 00:30:53,280 --> 00:30:56,640 on end, if you use your computer a lot and for quite a long period of time, 611 00:30:56,640 --> 00:30:58,060 something could go wrong. 612 00:30:58,060 --> 00:31:02,100 Maybe you accidentally bump the desktop or the laptop, the result of which 613 00:31:02,100 --> 00:31:04,890 is that this reading head might actually strike the platter 614 00:31:04,890 --> 00:31:07,980 and make a dent in it or some kind of scratch which actually will corrupt, 615 00:31:07,980 --> 00:31:10,270 not only some of the data perhaps, but might even 616 00:31:10,270 --> 00:31:14,250 stop the whole device from working if the reading head no longer functions 617 00:31:14,250 --> 00:31:14,920 properly. 618 00:31:14,920 --> 00:31:17,280 Moreover, anything that's physical like this 619 00:31:17,280 --> 00:31:20,520 isn't going to spin all that fast at the end of the day. 620 00:31:20,520 --> 00:31:24,250 Now technically, a hard drive like this might spin 7,200 times per minute 621 00:31:24,250 --> 00:31:28,560 or even 10,000 times per minute, but that's much, much slower 622 00:31:28,560 --> 00:31:31,200 than the speed with which electrons travel 623 00:31:31,200 --> 00:31:33,357 as they would in something like RAM. 624 00:31:33,357 --> 00:31:35,190 Well, fortunately, it turns out that there's 625 00:31:35,190 --> 00:31:39,070 something in between those technologies that doesn't have moving parts, 626 00:31:39,070 --> 00:31:43,740 but that's not quite as fast as RAM, but that is non-volatile, 627 00:31:43,740 --> 00:31:46,350 whereby it will store your data persistently 628 00:31:46,350 --> 00:31:47,820 even when the power is off. 629 00:31:47,820 --> 00:31:53,280 And this is so-called flash memory or a Solid State Disk, SSD, in this case 630 00:31:53,280 --> 00:31:53,790 here. 631 00:31:53,790 --> 00:31:57,660 It's a smaller device, whereas typical hard drives that have moving parts 632 00:31:57,660 --> 00:32:00,300 are very often 3 and 1/2 inches, although 2 and 1/2 inch 633 00:32:00,300 --> 00:32:03,210 versions do exist as well, in diameter. 634 00:32:03,210 --> 00:32:08,490 A solid state drive tends to be only 2.5 inches in width 635 00:32:08,490 --> 00:32:11,220 so that it actually fits inside of computers in the same slots 636 00:32:11,220 --> 00:32:14,580 that older more mechanical hard drives might fit. 637 00:32:14,580 --> 00:32:16,020 But it doesn't have moving parts. 638 00:32:16,020 --> 00:32:19,144 In fact, if we open it up, you'll see something very reminiscent of the RAM 639 00:32:19,144 --> 00:32:19,860 we saw earlier. 640 00:32:19,860 --> 00:32:24,390 But the technology inside of this device is such that the data persists, 641 00:32:24,390 --> 00:32:27,720 even when your battery dies or you unplug your laptop or desktop. 642 00:32:27,720 --> 00:32:33,990 But the upside of an SSD, being entirely electronic, is that it's much faster. 643 00:32:33,990 --> 00:32:35,790 And so this means that your programs will 644 00:32:35,790 --> 00:32:38,250 load faster when you double-click them, your files 645 00:32:38,250 --> 00:32:40,410 will open up faster when you double-click on them. 646 00:32:40,410 --> 00:32:44,160 Anything you might do or save to your hard drive or solid state drive, 647 00:32:44,160 --> 00:32:46,920 in this case, will actually get saved much more quickly, which 648 00:32:46,920 --> 00:32:50,801 means you might see a little hourglass or spinning beachball much less 649 00:32:50,801 --> 00:32:51,300 frequently. 650 00:32:51,300 --> 00:32:55,230 And your computer is going to behave and certainly feel faster. 651 00:32:55,230 --> 00:32:58,830 Now the catch is that solid state drives, theoretically, 652 00:32:58,830 --> 00:33:02,340 won't necessarily last as long, depending on the quality of the brand 653 00:33:02,340 --> 00:33:04,470 and the technology being used whereby they only 654 00:33:04,470 --> 00:33:06,030 have a finite number of writes. 655 00:33:06,030 --> 00:33:09,070 You can read from them nearly as much as you want. 656 00:33:09,070 --> 00:33:12,600 But over time, they'll degrade in terms of how many times 657 00:33:12,600 --> 00:33:13,830 you can keep writing to them. 658 00:33:13,830 --> 00:33:15,570 Now, for many people this might be a non-issue, 659 00:33:15,570 --> 00:33:18,690 but to mitigate against this, has the industry also introduced what are 660 00:33:18,690 --> 00:33:20,170 called hybrid drives-- 661 00:33:20,170 --> 00:33:23,850 hard drives that might be the same size as this or the same size 662 00:33:23,850 --> 00:33:26,820 as a 3 and 1/2 inch drive like the spinning mechanical device we 663 00:33:26,820 --> 00:33:30,540 saw a moment ago in our animated form-- 664 00:33:30,540 --> 00:33:33,330 but they might have both some solid state memory 665 00:33:33,330 --> 00:33:38,010 and some mechanical hard drive memory so that you might have a few megabytes 666 00:33:38,010 --> 00:33:40,470 or gigabytes of solid state memory. 667 00:33:40,470 --> 00:33:44,220 And you might have a few gigabytes or terabytes of traditional hard disk 668 00:33:44,220 --> 00:33:44,910 space. 669 00:33:44,910 --> 00:33:48,870 And the device itself moves your data around in a clever way 670 00:33:48,870 --> 00:33:51,360 so that it tries to keep as much of the data that you 671 00:33:51,360 --> 00:33:55,170 want to use, at a given moment, on the solid state part of the device 672 00:33:55,170 --> 00:33:57,300 so that it's readily accessible for you. 673 00:33:57,300 --> 00:33:59,970 And the data that you might not need, right then and there, 674 00:33:59,970 --> 00:34:02,340 stays on the slower, more mechanical device 675 00:34:02,340 --> 00:34:04,920 where, nonetheless, you have a lot more storage. 676 00:34:04,920 --> 00:34:07,860 Now flash memory is something you might have heard about before now, 677 00:34:07,860 --> 00:34:09,920 but in the form of these things here, USB 678 00:34:09,920 --> 00:34:12,971 sticks that might store 1 gigabyte or 16 gigabytes or more. 679 00:34:12,971 --> 00:34:15,720 But it's data that you might want to carry around on your keychain 680 00:34:15,720 --> 00:34:18,030 or in your pocket or keep around on your desk simply 681 00:34:18,030 --> 00:34:20,519 for transferring files from one computer to another 682 00:34:20,519 --> 00:34:22,339 or keeping some data with you. 683 00:34:22,339 --> 00:34:24,630 They tend to be slower though, than solid state drives. 684 00:34:24,630 --> 00:34:26,340 They tend to be less reliable. 685 00:34:26,340 --> 00:34:29,420 But they also tend to be much less expensive, but also smaller 686 00:34:29,420 --> 00:34:30,330 in capacity. 687 00:34:30,330 --> 00:34:33,152 But the technology is very similar in spirit. 688 00:34:33,152 --> 00:34:34,860 If you need more storage space than that, 689 00:34:34,860 --> 00:34:38,272 you might actually carry around with you a solid state drive externally. 690 00:34:38,272 --> 00:34:40,480 So it might be a little bigger, and a little heavier, 691 00:34:40,480 --> 00:34:42,605 and not something you want to put on your keychain. 692 00:34:42,605 --> 00:34:46,620 But this might store 256 gigabytes of space 693 00:34:46,620 --> 00:34:51,570 or even a terabyte of space, all of which is now carried around externally. 694 00:34:51,570 --> 00:34:54,180 And via some kind of cable can you plug this device 695 00:34:54,180 --> 00:34:57,540 into your laptop or desktop or maybe a friend or colleague's computer 696 00:34:57,540 --> 00:35:00,930 so that you can share files without having a local network. 697 00:35:00,930 --> 00:35:04,590 If you need even more storage than that, 1 terabyte, 2 terabytes, 4 terabytes, 698 00:35:04,590 --> 00:35:08,130 or more, you might actually have another type of external hard drive 699 00:35:08,130 --> 00:35:11,910 inside of which is one of those older more traditional mechanical drives, 700 00:35:11,910 --> 00:35:17,250 the 3 and 1/2 inch disk devices, that might store much, much, much more data. 701 00:35:17,250 --> 00:35:20,050 But the price you pay is that it's a mechanical device. 702 00:35:20,050 --> 00:35:22,390 It might be, therefore, a little bit slower. 703 00:35:22,390 --> 00:35:24,540 And so ultimately, there's this trade-off 704 00:35:24,540 --> 00:35:27,600 between how much space you get, how much money you're spending, 705 00:35:27,600 --> 00:35:31,957 and how quickly you can get data from and to that external device. 706 00:35:31,957 --> 00:35:35,040 In fact, there's this whole series of trade-offs that we've seen thus far. 707 00:35:35,040 --> 00:35:37,200 And you can actually think of these various types 708 00:35:37,200 --> 00:35:40,200 of memory inside of a computer like a funnel of sorts 709 00:35:40,200 --> 00:35:44,310 whereby you have a pretty big opening where you keep a lot of your data 710 00:35:44,310 --> 00:35:45,930 on the biggest of your devices. 711 00:35:45,930 --> 00:35:49,380 But the goal is to get that data closer and closer and closer 712 00:35:49,380 --> 00:35:52,690 to your computer's brain where it can do some actual work. 713 00:35:52,690 --> 00:35:55,740 Indeed, if you think of the CPU as being at the bottom of this funnel, 714 00:35:55,740 --> 00:35:58,560 that's to whom you want to get all of this data. 715 00:35:58,560 --> 00:36:02,010 So throughout this funnel, you might have your hard disk or your solid state 716 00:36:02,010 --> 00:36:05,190 disk up here which stores a lot of your files a lot of your programs 717 00:36:05,190 --> 00:36:09,120 persistently in a nonvolatile way so that it's permanent even when 718 00:36:09,120 --> 00:36:11,910 the power or battery no longer works. 719 00:36:11,910 --> 00:36:16,740 But that hard disk or solid state disk ultimately feeds information down 720 00:36:16,740 --> 00:36:18,600 to your computer's RAM. 721 00:36:18,600 --> 00:36:21,480 But the ram is not the last stop before the computer's CPU. 722 00:36:21,480 --> 00:36:24,150 It turns out that there's other types of memory 723 00:36:24,150 --> 00:36:28,420 that a computer has that you might even see mentioned on your computer screen. 724 00:36:28,420 --> 00:36:30,930 So if up here you have your disk, whether it's 725 00:36:30,930 --> 00:36:33,930 a hard disk drive or a solid state disk drive, 726 00:36:33,930 --> 00:36:36,060 you might have quite a bit of this. 727 00:36:36,060 --> 00:36:41,550 This might be in the order of gigabytes or terabytes, billions of bytes 728 00:36:41,550 --> 00:36:43,080 or trillions of bytes. 729 00:36:43,080 --> 00:36:48,330 That gets fed into, ultimately, your computer's RAM, which probably exists 730 00:36:48,330 --> 00:36:51,600 on the order of these days of gigabytes, but fewer gigabytes 731 00:36:51,600 --> 00:36:52,810 than your actual disk. 732 00:36:52,810 --> 00:36:55,140 Down here you're going to have your CPU. 733 00:36:55,140 --> 00:36:58,410 And indeed, the goal is to get your data to the CPU. 734 00:36:58,410 --> 00:37:00,660 And the CPU, of course, is measured not in bytes 735 00:37:00,660 --> 00:37:02,790 but in gigahertz-- the number of billions of things 736 00:37:02,790 --> 00:37:05,520 it can do per second with that data. 737 00:37:05,520 --> 00:37:09,030 But there's also tends to be something in between RAM and CPU. 738 00:37:09,030 --> 00:37:14,130 There's often something called Level 3 cache, which might 739 00:37:14,130 --> 00:37:16,590 exist in the form of megabytes worth. 740 00:37:16,590 --> 00:37:19,980 Then it goes into what's called Level 2 cache, which 741 00:37:19,980 --> 00:37:21,840 is another type of memory, which also might 742 00:37:21,840 --> 00:37:26,610 be in the kilobyte or thousands of bytes or megabyte range. 743 00:37:26,610 --> 00:37:30,570 And then there might be L1 cache, which doesn't quite 744 00:37:30,570 --> 00:37:31,680 fit on this on the screen. 745 00:37:31,680 --> 00:37:32,310 But that's OK. 746 00:37:32,310 --> 00:37:35,460 Because it hints at just how small of a physical device this is, 747 00:37:35,460 --> 00:37:38,637 which might be on the order of, say, kilobytes. 748 00:37:38,637 --> 00:37:39,720 So these values will vary. 749 00:37:39,720 --> 00:37:42,160 And they'll certainly change over time. 750 00:37:42,160 --> 00:37:45,480 And so what's the pattern, then, among these various types of memory 751 00:37:45,480 --> 00:37:47,130 leading to the CPU? 752 00:37:47,130 --> 00:37:49,770 Well, the disk, whether a hard disk or solid state disk, 753 00:37:49,770 --> 00:37:52,800 is not only nonvolatile-- sticks around permanently, 754 00:37:52,800 --> 00:37:56,640 and it's where your files and your programs are stored when the power is 755 00:37:56,640 --> 00:37:57,391 off-- 756 00:37:57,391 --> 00:37:59,640 that's the biggest of these various types of memories, 757 00:37:59,640 --> 00:38:00,960 but it's also the slowest. 758 00:38:00,960 --> 00:38:04,520 Even solid state is slower than some of these other memories 759 00:38:04,520 --> 00:38:06,510 below it on the funnel here. 760 00:38:06,510 --> 00:38:10,170 Meanwhile, RAM tends to exist, still on the order of gigabytes, 761 00:38:10,170 --> 00:38:13,260 but maybe 1 gigabyte, 4 gigabytes, 16, maybe more 762 00:38:13,260 --> 00:38:15,300 if you've splurged on a really nice computer. 763 00:38:15,300 --> 00:38:17,610 But RAM recall is where programs and files 764 00:38:17,610 --> 00:38:21,750 live when you double-clicked or opened them in order to use them 765 00:38:21,750 --> 00:38:23,610 on your computer at a given moment. 766 00:38:23,610 --> 00:38:26,190 Meanwhile though-- and this is values you don't really 767 00:38:26,190 --> 00:38:28,509 control because they tend to be associated closely 768 00:38:28,509 --> 00:38:30,300 with the CPU or the motherboard that you've 769 00:38:30,300 --> 00:38:35,460 bought as part of your computer-- that RAM feeds information into Level 3 770 00:38:35,460 --> 00:38:41,820 and/or Level 2 and/or Level 1 cache in turn so that it's less memory there, 771 00:38:41,820 --> 00:38:43,860 but it's super, super fast. 772 00:38:43,860 --> 00:38:46,960 And that ensures that, even though there's less of this memory-- 773 00:38:46,960 --> 00:38:50,490 Level 1 cache exists in smaller quantities than Level 3-- 774 00:38:50,490 --> 00:38:52,230 that funnel is just always filled. 775 00:38:52,230 --> 00:38:54,396 There's always something at the bottom of the funnel 776 00:38:54,396 --> 00:38:55,740 ready to be fed into the CPU. 777 00:38:55,740 --> 00:38:59,820 So the CPU never, theoretically, has to wait for any data-- 778 00:38:59,820 --> 00:39:03,720 to get numbers to crunch, or text to display, or the like. 779 00:39:03,720 --> 00:39:07,230 Meanwhile, there exists, turns out, tiny little pieces 780 00:39:07,230 --> 00:39:11,040 of memory in a computer that we'll give a name to called registers. 781 00:39:11,040 --> 00:39:16,740 And these registers typically only hold 1 byte or 4 bytes or 8 bytes total. 782 00:39:16,740 --> 00:39:18,930 So they're the smallest unit of memory. 783 00:39:18,930 --> 00:39:22,620 But it's in those registers that the CPU stores values 784 00:39:22,620 --> 00:39:27,100 like numbers like those decimal numbers we discussed earlier. 785 00:39:27,100 --> 00:39:29,644 And if it wants to perform arithmetic of any sort, 786 00:39:29,644 --> 00:39:32,560 it stores those values in these registers, actually performs the math, 787 00:39:32,560 --> 00:39:35,190 stores the result in another register, so it's, then, ready 788 00:39:35,190 --> 00:39:39,210 to be loaded back through this funnel into something like the computer's RAM 789 00:39:39,210 --> 00:39:41,850 or ultimately saved back to disk. 790 00:39:41,850 --> 00:39:43,500 But there's another trade-off here. 791 00:39:43,500 --> 00:39:47,100 Besides the top of this funnel being bigger and slower, 792 00:39:47,100 --> 00:39:50,036 and the bottom of this funnel being smaller and faster, 793 00:39:50,036 --> 00:39:52,410 the bottom of the funnel also tends to be more expensive, 794 00:39:52,410 --> 00:39:54,870 which also explains, in part, why you see less 795 00:39:54,870 --> 00:39:56,900 of this memory inside of a computer. 796 00:39:56,900 --> 00:39:59,239 The Level 1 cache might be more expensive than ram, 797 00:39:59,239 --> 00:40:01,530 so you have less of it and, technically, you don't even 798 00:40:01,530 --> 00:40:03,696 need as much of it so long as there's enough to keep 799 00:40:03,696 --> 00:40:05,700 data waiting for the CPU. 800 00:40:05,700 --> 00:40:08,520 But cost is certainly another trade-off as well. 801 00:40:08,520 --> 00:40:11,746 But the types of numbers that you, as a consumer, might care about, really, 802 00:40:11,746 --> 00:40:13,620 would be how big the disk in your computer is 803 00:40:13,620 --> 00:40:16,229 and how much data and programs and files you can store, 804 00:40:16,229 --> 00:40:17,520 how much RAM your computer has. 805 00:40:17,520 --> 00:40:19,920 Because that correlates with just how much work 806 00:40:19,920 --> 00:40:22,160 you can do at once, how many files and programs you 807 00:40:22,160 --> 00:40:25,450 can keep running simultaneously without having to quit any of them. 808 00:40:25,450 --> 00:40:28,830 And so cache, finally, which is more closely 809 00:40:28,830 --> 00:40:32,380 tied to the CPU and the motherboard in your computer and, therefore, 810 00:40:32,380 --> 00:40:35,610 isn't really a number you have as much control over as the consumer, 811 00:40:35,610 --> 00:40:38,730 just ensures that the data is actually ready. 812 00:40:38,730 --> 00:40:40,760 Now this might all sound fairly technical. 813 00:40:40,760 --> 00:40:44,220 But these caches, whether Level 3 or 2 or 1 are actually 814 00:40:44,220 --> 00:40:47,230 quite similar to techniques that we humans use in the real world, 815 00:40:47,230 --> 00:40:51,200 for instance, even at your local candy store. 816 00:40:51,200 --> 00:40:53,300 Here's my candy store, and I'm open for business. 817 00:40:53,300 --> 00:40:55,860 818 00:40:55,860 --> 00:40:56,880 SPEAKER: Candy, please? 819 00:40:56,880 --> 00:40:58,630 DAVID J. MALAN: Let me get you some candy. 820 00:40:58,630 --> 00:41:00,250 [FOOTSTEPS] 821 00:41:00,250 --> 00:41:05,381 822 00:41:05,381 --> 00:41:05,880 Thank you. 823 00:41:05,880 --> 00:41:07,816 Come again. 824 00:41:07,816 --> 00:41:10,190 Now that was not very efficient to have to go all the way 825 00:41:10,190 --> 00:41:12,330 and back into the store room to get the candy. 826 00:41:12,330 --> 00:41:15,270 Much more efficient would be to keep it closer to me 827 00:41:15,270 --> 00:41:19,770 in a place that's faster to access much like a cache of candy right here 828 00:41:19,770 --> 00:41:20,520 on the counter. 829 00:41:20,520 --> 00:41:22,394 In fact, let me go ahead and ready that cash. 830 00:41:22,394 --> 00:41:24,496 [FOOTSTEPS] 831 00:41:24,496 --> 00:41:28,490 832 00:41:28,490 --> 00:41:33,106 And now, with this cache of candy am I open for business again. 833 00:41:33,106 --> 00:41:34,390 SPEAKER: Candy, please? 834 00:41:34,390 --> 00:41:35,473 DAVID J. MALAN: Thank you. 835 00:41:35,473 --> 00:41:36,550 Come again. 836 00:41:36,550 --> 00:41:38,950 Now this is a small cache of candy, but it's fast. 837 00:41:38,950 --> 00:41:42,850 And, with it, can I provide my customers or really my CPU with information 838 00:41:42,850 --> 00:41:44,230 much more quickly. 839 00:41:44,230 --> 00:41:47,250 840 00:41:47,250 --> 00:41:50,900 Now we can actually see the sizes of these caches in that same output 841 00:41:50,900 --> 00:41:53,404 that we saw earlier from Windows and Mac OS. 842 00:41:53,404 --> 00:41:55,820 For instance, if we look again at the Windows Task Manager 843 00:41:55,820 --> 00:41:59,630 and look down here, you can actually see that this particular laptop 844 00:41:59,630 --> 00:42:03,800 had L1 cache on the order of 128 kilobytes or thousands of bytes. 845 00:42:03,800 --> 00:42:09,170 It had 512 kilobytes of L2 cache, and 4 megabytes of L3 cache. 846 00:42:09,170 --> 00:42:12,240 Meanwhile, if we take a look at that same MacBook Pro from earlier, 847 00:42:12,240 --> 00:42:17,450 you'll see that it has 256 kilobytes of cache, 4 megabytes of L3 cache, 848 00:42:17,450 --> 00:42:21,260 doesn't happen to mention L1 cache, but odds are, it's indeed there on the CPU, 849 00:42:21,260 --> 00:42:24,230 just not reported by this program. 850 00:42:24,230 --> 00:42:28,130 Now what else is inside or really outside of a computer? 851 00:42:28,130 --> 00:42:31,370 In fact, let's start to take a look at things, perhaps, more familiar. 852 00:42:31,370 --> 00:42:35,930 Now these are just graphical depictions of connectors or sockets 853 00:42:35,930 --> 00:42:39,590 on the back of your computer into which you might have very well plugged 854 00:42:39,590 --> 00:42:41,040 in various devices. 855 00:42:41,040 --> 00:42:43,910 In fact, this collection of ports here are all 856 00:42:43,910 --> 00:42:46,610 related to monitors or displays. 857 00:42:46,610 --> 00:42:49,100 So a computer, like a desktop computer, tends 858 00:42:49,100 --> 00:42:50,940 not to come with a monitor built in. 859 00:42:50,940 --> 00:42:54,290 And if it does, indeed not, you might need to plug-in an external monitor 860 00:42:54,290 --> 00:42:56,870 using something like mini DisplayPort-- 861 00:42:56,870 --> 00:43:00,050 very commonly found on laptops, especially if you want to have, 862 00:43:00,050 --> 00:43:01,820 not just your primary laptop display, but 863 00:43:01,820 --> 00:43:04,430 a secondary, a bigger monitor on your desk-- 864 00:43:04,430 --> 00:43:07,340 DisplayPort, which is the same idea, but a larger connector 865 00:43:07,340 --> 00:43:10,430 that you might typically have on a desktop plugging into a monitor-- 866 00:43:10,430 --> 00:43:13,730 HDMI, which you might have, not only on your laptop or desktop, 867 00:43:13,730 --> 00:43:17,390 but possibly even on your TV at home because this is also the type of cable 868 00:43:17,390 --> 00:43:20,960 that you would use to plug a TV into some kind of set-top device 869 00:43:20,960 --> 00:43:21,830 in your living room. 870 00:43:21,830 --> 00:43:23,020 And then, lastly, VGA-- 871 00:43:23,020 --> 00:43:24,770 still on the list, even though it's super, 872 00:43:24,770 --> 00:43:28,520 super old and not nearly as featureful as these other technologies. 873 00:43:28,520 --> 00:43:31,610 But you'll very often find at universities like this and companies 874 00:43:31,610 --> 00:43:38,330 that have long had projectors installed in their rooms, this older technology, 875 00:43:38,330 --> 00:43:41,430 and so it, too, is still pretty common. 876 00:43:41,430 --> 00:43:44,730 Now, what else might we want to plug into a computer? 877 00:43:44,730 --> 00:43:48,980 Well, any number of devices as well-- in fact, if you've ever seen this symbol, 878 00:43:48,980 --> 00:43:52,840 that means you have a port on your computer, desktop or laptop, into which 879 00:43:52,840 --> 00:43:55,090 you can plug a whole range of devices. 880 00:43:55,090 --> 00:43:58,100 If you've ever needed to plug a printer into your computer, 881 00:43:58,100 --> 00:44:02,450 you might use the port label with this-- a scanner, a digital camera, 882 00:44:02,450 --> 00:44:06,380 any number of other peripheral devices might be connected to your computer 883 00:44:06,380 --> 00:44:07,790 by way of this device here. 884 00:44:07,790 --> 00:44:10,780 Even your mouse and your keyboard, if they're not already wireless, 885 00:44:10,780 --> 00:44:12,860 would be plugged in with this device here. 886 00:44:12,860 --> 00:44:15,189 And it might actually take any number of shapes, 887 00:44:15,189 --> 00:44:17,730 though thankfully, some of these are more common than others. 888 00:44:17,730 --> 00:44:19,660 This is the universal serial bus-- 889 00:44:19,660 --> 00:44:22,040 where a bus as a term technologically that 890 00:44:22,040 --> 00:44:25,970 refers to some kind of medium along which data can travel, much like a bus 891 00:44:25,970 --> 00:44:27,380 travels down a street. 892 00:44:27,380 --> 00:44:31,730 So USB has a whole bunch of different connectors as depicted here. 893 00:44:31,730 --> 00:44:34,490 And the most common of which is just this rectangular one that, 894 00:44:34,490 --> 00:44:38,120 rather annoyingly, only 50% of the time do you, if you're like me, 895 00:44:38,120 --> 00:44:42,470 plug the cable in the right way because it can only go in one certain way. 896 00:44:42,470 --> 00:44:43,970 So you might have to flip it around. 897 00:44:43,970 --> 00:44:46,345 But on the other end of that cable might be another type, 898 00:44:46,345 --> 00:44:50,960 not USB A, but USB B, which is commonly used 899 00:44:50,960 --> 00:44:54,080 to plug into the back of scanners and printers and beyond. 900 00:44:54,080 --> 00:44:57,590 More recently, though, have companies like Apples and others 901 00:44:57,590 --> 00:44:59,660 started using using USB C-- 902 00:44:59,660 --> 00:45:03,920 a third type of connector that, thankfully, can go either top down 903 00:45:03,920 --> 00:45:07,280 or bottom up, thereby, not having to think as much when 904 00:45:07,280 --> 00:45:08,640 you want to plug in a device. 905 00:45:08,640 --> 00:45:11,723 But there's any number of other variants of these connectors commonly seen 906 00:45:11,723 --> 00:45:15,830 on cell phones, in fact, for chargers and data cables, all of which support 907 00:45:15,830 --> 00:45:16,730 USB. 908 00:45:16,730 --> 00:45:19,310 Now the USB standard, itself, has evolved over time. 909 00:45:19,310 --> 00:45:22,970 So the latest and greatest version of USB devices and connectors 910 00:45:22,970 --> 00:45:26,930 are actually much faster than some of the historically older devices 911 00:45:26,930 --> 00:45:27,530 and cables. 912 00:45:27,530 --> 00:45:30,440 And so it actually does matter what kind of cable you have 913 00:45:30,440 --> 00:45:33,920 and what device you have as to whether or not it will transfer data 914 00:45:33,920 --> 00:45:35,390 as fast as you might like. 915 00:45:35,390 --> 00:45:36,690 Now why is this important? 916 00:45:36,690 --> 00:45:41,600 Well, one of the devices you can connect to a computer, typically via USB cable, 917 00:45:41,600 --> 00:45:43,430 is something like an external hard drive. 918 00:45:43,430 --> 00:45:46,820 And even if you have a super fast external hard drive that 919 00:45:46,820 --> 00:45:49,880 is, say, an SSD underneath the hood, if you're 920 00:45:49,880 --> 00:45:52,512 using a slower older USB cable or technology, 921 00:45:52,512 --> 00:45:54,470 you might not, nonetheless, be able to transfer 922 00:45:54,470 --> 00:45:58,790 that data off a very fast device over a slow cable to your computer. 923 00:45:58,790 --> 00:46:03,020 So keeping an eye out for the latest versions of these technologies like USB 924 00:46:03,020 --> 00:46:05,180 can actually be quite important. 925 00:46:05,180 --> 00:46:08,600 But, of course, you might not need cables at all for certain devices. 926 00:46:08,600 --> 00:46:12,110 Of course, if you want to use Wi-Fi or wireless internet in your home, 927 00:46:12,110 --> 00:46:16,070 in the airport, in Starbucks, or elsewhere, your computer just 928 00:46:16,070 --> 00:46:19,382 needs to support Wi-Fi, which odds are, it very much does these days. 929 00:46:19,382 --> 00:46:21,590 And you might see a symbol somewhere in your computer 930 00:46:21,590 --> 00:46:23,750 like this depicting as much. 931 00:46:23,750 --> 00:46:26,330 But not everything operates over Wi-Fi. 932 00:46:26,330 --> 00:46:30,260 In fact, devices that you might want to plug into or connect to your computer 933 00:46:30,260 --> 00:46:32,900 without a cable would tend to use not Wi-Fi, 934 00:46:32,900 --> 00:46:35,300 but another wireless technology called Bluetooth 935 00:46:35,300 --> 00:46:39,119 that Windows computers and Macs alike support these days. 936 00:46:39,119 --> 00:46:40,910 So in fact, if you have a wireless keyboard 937 00:46:40,910 --> 00:46:43,910 at home or at work, or a wireless mouse, or if you 938 00:46:43,910 --> 00:46:47,900 have any number of other devices that, somehow, are wirelessly communicating 939 00:46:47,900 --> 00:46:51,376 with your computer, perhaps even your headphones these days, odds are, 940 00:46:51,376 --> 00:46:53,750 those are using a technology called Bluetooth, which have 941 00:46:53,750 --> 00:46:56,160 a limited range of just so many feeds. 942 00:46:56,160 --> 00:46:59,150 943 00:46:59,150 --> 00:47:02,330 They don't afford you nearly as much distance as something like Wi-Fi does, 944 00:47:02,330 --> 00:47:03,460 but that's a good thing. 945 00:47:03,460 --> 00:47:05,210 Because generally, this technology is used 946 00:47:05,210 --> 00:47:08,720 to interconnect your personal devices to your personal computer 947 00:47:08,720 --> 00:47:11,810 and not really to others around you. 948 00:47:11,810 --> 00:47:14,960 So with all of these various devices inside of and, potentially, 949 00:47:14,960 --> 00:47:17,041 connected outside of my computer, what is 950 00:47:17,041 --> 00:47:19,165 it that ensures that they can all intercommunicate? 951 00:47:19,165 --> 00:47:21,580 And what is it that ensures that all of this works? 952 00:47:21,580 --> 00:47:23,580 Well, at the end of the day it's the, so-called, 953 00:47:23,580 --> 00:47:26,300 operating system whether it's Mac OS or Windows, 954 00:47:26,300 --> 00:47:29,390 which is simply software, that either you or, more likely, 955 00:47:29,390 --> 00:47:32,930 some manufacturer pre-installed on the computer that you bought. 956 00:47:32,930 --> 00:47:36,320 And that software is installed on your hard drive or your solid state disk 957 00:47:36,320 --> 00:47:37,876 so that it's there persistently. 958 00:47:37,876 --> 00:47:40,250 And so that, even when you unwrap that shrink-wrapped box 959 00:47:40,250 --> 00:47:43,430 that has had no power for some time, the operating system is ready to go. 960 00:47:43,430 --> 00:47:46,304 And, indeed, when you hit the power button on your laptop or desktop, 961 00:47:46,304 --> 00:47:51,170 it's the operating system, ultimately, that is loaded into RAM from disk, 962 00:47:51,170 --> 00:47:52,949 and is what you ultimately see. 963 00:47:52,949 --> 00:47:55,490 In fact, it's the operating system that gives you, literally, 964 00:47:55,490 --> 00:47:58,010 the graphical windows that you see and the icons and the buttons 965 00:47:58,010 --> 00:47:58,850 that you can click. 966 00:47:58,850 --> 00:48:01,220 But more importantly, it's the operating system 967 00:48:01,220 --> 00:48:03,862 that knows how to talk to your keyboard and your mouse. 968 00:48:03,862 --> 00:48:05,570 It's your operating system that knows how 969 00:48:05,570 --> 00:48:07,222 to display information on the screen. 970 00:48:07,222 --> 00:48:08,930 It's your operating system that knows how 971 00:48:08,930 --> 00:48:12,380 to move things around in memory and disk and reading and writing 972 00:48:12,380 --> 00:48:13,877 all of that information. 973 00:48:13,877 --> 00:48:16,460 And that's all thanks to software that comes with an operating 974 00:48:16,460 --> 00:48:18,500 system called device drivers-- 975 00:48:18,500 --> 00:48:22,580 special software designed to talk to a certain model of printer, 976 00:48:22,580 --> 00:48:25,449 to a certain model of camera, or scanner, and the like. 977 00:48:25,449 --> 00:48:28,490 And, in fact, even when Windows or Mac OS or Linux or any other operating 978 00:48:28,490 --> 00:48:32,300 system doesn't recognize some device-- maybe because it didn't exist when 979 00:48:32,300 --> 00:48:36,059 Windows or Mac OS or Linux was installed on your computer-- 980 00:48:36,059 --> 00:48:38,600 well, you can very often download new software device drivers 981 00:48:38,600 --> 00:48:41,510 from the manufacturer's website of the manufacturer that 982 00:48:41,510 --> 00:48:42,960 made that new technology. 983 00:48:42,960 --> 00:48:46,610 And that can teach Windows and Mac OS and Linux and others 984 00:48:46,610 --> 00:48:48,280 to understand that new hardware. 985 00:48:48,280 --> 00:48:51,800 And so there is a future-proofing built into these operating systems 986 00:48:51,800 --> 00:48:54,230 because, at the end of the day, they're just software. 987 00:48:54,230 --> 00:48:56,480 And so it's this intersection of hardware and software 988 00:48:56,480 --> 00:48:59,660 that makes these computers just so powerful. 989 00:48:59,660 --> 00:49:02,870 Now, it's all fun and good to talk about hardware 990 00:49:02,870 --> 00:49:04,730 and see it depicted on the screen. 991 00:49:04,730 --> 00:49:07,880 But let's actually get our hands dirty here and actually enter 992 00:49:07,880 --> 00:49:10,940 into our own laboratory and take a look on the outside 993 00:49:10,940 --> 00:49:14,510 and inside of some actual computers. 994 00:49:14,510 --> 00:49:18,354 I'm here now with Dr. Colton Ogden for a look inside a couple of computers. 995 00:49:18,354 --> 00:49:20,270 COLTON OGDEN: Happy to be with you guys today. 996 00:49:20,270 --> 00:49:23,057 We have an IBM ThinkPad laptop here. 997 00:49:23,057 --> 00:49:24,640 Nobody really needs to use it anymore. 998 00:49:24,640 --> 00:49:27,681 So I figured we'd show you guys what a computer looks like on the outside 999 00:49:27,681 --> 00:49:29,910 before we start digging in on the inside. 1000 00:49:29,910 --> 00:49:33,110 So you want to start off by maybe showing what some of these ports 1001 00:49:33,110 --> 00:49:34,100 are here on the laptop? 1002 00:49:34,100 --> 00:49:34,320 DAVID J. MALAN: Yeah. 1003 00:49:34,320 --> 00:49:34,820 Sure. 1004 00:49:34,820 --> 00:49:36,320 So here's one of those older ports. 1005 00:49:36,320 --> 00:49:37,861 And, indeed, this is an older laptop. 1006 00:49:37,861 --> 00:49:41,600 This is a so-called VGA port into which you would plug a cable to connect it, 1007 00:49:41,600 --> 00:49:44,390 either to an external monitor, or more realistically, on a campus 1008 00:49:44,390 --> 00:49:45,420 or in a workplace. 1009 00:49:45,420 --> 00:49:47,960 It's like a projector so that other people can see. 1010 00:49:47,960 --> 00:49:52,170 If you can believe it, this is an RJ11 jack for an old school modem or a phone 1011 00:49:52,170 --> 00:49:52,670 cable. 1012 00:49:52,670 --> 00:49:55,430 So that you could actually dial up to AOL. 1013 00:49:55,430 --> 00:49:56,660 COLTON OGDEN: Old school. 1014 00:49:56,660 --> 00:49:58,760 DAVID J.MALAN: Here's an RJ45 connector, which 1015 00:49:58,760 --> 00:50:02,450 actually looks like this here, as sort of a fat network cable. 1016 00:50:02,450 --> 00:50:06,080 And that's what you would use to get online with wired internet. 1017 00:50:06,080 --> 00:50:09,620 Here, we have a microphone jack, if you have an external mic, headphone jack 1018 00:50:09,620 --> 00:50:13,940 if you want to listen to music at work, USB to connect 1019 00:50:13,940 --> 00:50:16,010 any number of external devices. 1020 00:50:16,010 --> 00:50:16,520 And oh. 1021 00:50:16,520 --> 00:50:18,040 What's this one we've got over here? 1022 00:50:18,040 --> 00:50:20,390 COLTON OGDEN: It looks like we've got a DVD port. 1023 00:50:20,390 --> 00:50:21,640 You don't see these very often anymore. 1024 00:50:21,640 --> 00:50:23,681 It's not going to work because the laptop is off. 1025 00:50:23,681 --> 00:50:26,070 But we also have a couple of USB ports here on the side. 1026 00:50:26,070 --> 00:50:28,460 And I think that's pretty much all we have on this guy. 1027 00:50:28,460 --> 00:50:28,570 DAVID J. MALAN: Yeah. 1028 00:50:28,570 --> 00:50:31,430 A DVD or CD drive is what's known as optical storage. 1029 00:50:31,430 --> 00:50:34,700 And it really is just a piece of plastic, the CD or DVD, 1030 00:50:34,700 --> 00:50:37,850 with some reflective material on it and little divots or pits that 1031 00:50:37,850 --> 00:50:40,760 are created with a laser that gets, then, read with the laser 1032 00:50:40,760 --> 00:50:43,220 so that you can actually write 0s and 1s by, 1033 00:50:43,220 --> 00:50:45,770 essentially, having a smooth surface or little bumps. 1034 00:50:45,770 --> 00:50:49,920 But it's increasingly falling into disuse as Flash Media of various sorts 1035 00:50:49,920 --> 00:50:51,260 is being used instead. 1036 00:50:51,260 --> 00:50:53,330 Well, why don't we not gut this, although, I do 1037 00:50:53,330 --> 00:50:55,640 see it's power cable sitting here. 1038 00:50:55,640 --> 00:50:59,330 So you'll notice that most laptops like this have power cables that one 1039 00:50:59,330 --> 00:51:02,330 go into the wall, then some other proprietary or standard connector that 1040 00:51:02,330 --> 00:51:03,890 goes into the laptop, and then a brick. 1041 00:51:03,890 --> 00:51:05,473 Sometimes that gets a little bit warm. 1042 00:51:05,473 --> 00:51:07,730 And what this brick is doing is it's actually 1043 00:51:07,730 --> 00:51:11,750 converting the 120 volts or 240 volts coming out of your wall 1044 00:51:11,750 --> 00:51:15,920 to far fewer volts that your laptop can actually tolerate. 1045 00:51:15,920 --> 00:51:18,020 Shall we take a look at the desktop next? 1046 00:51:18,020 --> 00:51:18,380 COLTON OGDEN: Yeah. 1047 00:51:18,380 --> 00:51:18,740 Perfect. 1048 00:51:18,740 --> 00:51:21,989 So let's go ahead and take a look at the internals of a computer with this guy 1049 00:51:21,989 --> 00:51:22,850 here. 1050 00:51:22,850 --> 00:51:27,540 So I'm going to go ahead and just take off the casing's lid here. 1051 00:51:27,540 --> 00:51:29,340 DAVID J. MALAN: And this is an older PC-- 1052 00:51:29,340 --> 00:51:29,620 COLTON OGDEN: Yes. 1053 00:51:29,620 --> 00:51:30,170 DAVID J. MALAN: --desktop right? 1054 00:51:30,170 --> 00:51:31,700 An older Windows PC. 1055 00:51:31,700 --> 00:51:34,817 And so you find that Mac computers aren't so readily taken apart. 1056 00:51:34,817 --> 00:51:36,650 In fact, that's one of the features of Apple 1057 00:51:36,650 --> 00:51:39,245 computers is that they have far fewer user serviceable parts, 1058 00:51:39,245 --> 00:51:41,120 but the price you pay, of course, is that you 1059 00:51:41,120 --> 00:51:43,905 can't upgrade them or reconfigure them, often using magnets to. 1060 00:51:43,905 --> 00:51:44,780 COLTON OGDEN: Indeed. 1061 00:51:44,780 --> 00:51:45,190 DAVID J. MALAN: All right. 1062 00:51:45,190 --> 00:51:46,600 So what do we have inside of here? 1063 00:51:46,600 --> 00:51:46,830 COLTON OGDEN: OK. 1064 00:51:46,830 --> 00:51:48,870 So we have, in here, a lot of the parts you were just 1065 00:51:48,870 --> 00:51:50,120 talking about in your lecture. 1066 00:51:50,120 --> 00:51:53,024 We have a CPU with its heat sink here, right in the middle. 1067 00:51:53,024 --> 00:51:54,690 DAVID J. MALAN: That's a huge heat sink. 1068 00:51:54,690 --> 00:51:55,525 And that does what? 1069 00:51:55,525 --> 00:51:56,900 COLTON OGDEN: It dissipates heat. 1070 00:51:56,900 --> 00:51:58,170 A CPU is very hot. 1071 00:51:58,170 --> 00:51:59,670 It's oscillating very fast. 1072 00:51:59,670 --> 00:52:04,080 And so the purpose of this is to, with all of these planes, disperse 1073 00:52:04,080 --> 00:52:08,370 the heat equally and then get rid of it alongside the fan 1074 00:52:08,370 --> 00:52:10,150 as well, which acts in tandem with it. 1075 00:52:10,150 --> 00:52:10,320 DAVID J. MALAN: Yeah. 1076 00:52:10,320 --> 00:52:12,420 It's a big fan, like you would have in the summertime. 1077 00:52:12,420 --> 00:52:12,900 COLTON OGDEN: Oh, yeah. 1078 00:52:12,900 --> 00:52:13,401 Definitely. 1079 00:52:13,401 --> 00:52:14,483 DAVID J. MALAN: All right. 1080 00:52:14,483 --> 00:52:15,960 And what about these green sticks? 1081 00:52:15,960 --> 00:52:17,850 COLTON OGDEN: These green sticks, we only have one in this laptop. 1082 00:52:17,850 --> 00:52:20,760 But this is actually a stick of RAM, so random access memory 1083 00:52:20,760 --> 00:52:23,209 where computers' programs are stored as they're loaded. 1084 00:52:23,209 --> 00:52:24,000 DAVID J. MALAN: OK. 1085 00:52:24,000 --> 00:52:26,776 And that's connected to this bigger green sheet, which is-- 1086 00:52:26,776 --> 00:52:29,150 COLTON OGDEN: This bigger green sheet is the motherboard. 1087 00:52:29,150 --> 00:52:31,230 It's sort of like the central hub for all the parts 1088 00:52:31,230 --> 00:52:32,688 working together with the computer. 1089 00:52:32,688 --> 00:52:35,160 It acts as sort of a messaging interface for everything. 1090 00:52:35,160 --> 00:52:35,420 DAVID J. MALAN: OK. 1091 00:52:35,420 --> 00:52:37,890 And now, doctor, can I take a look at that piece of RAM? 1092 00:52:37,890 --> 00:52:38,530 Do you need it? 1093 00:52:38,530 --> 00:52:39,090 COLTON OGDEN: Absolutely. 1094 00:52:39,090 --> 00:52:39,220 No. 1095 00:52:39,220 --> 00:52:40,230 Let's take it out of here. 1096 00:52:40,230 --> 00:52:40,410 DAVID J. MALAN: All right. 1097 00:52:40,410 --> 00:52:42,045 So that just snaps right out. 1098 00:52:42,045 --> 00:52:42,650 COLTON OGDEN: Snaps right out. 1099 00:52:42,650 --> 00:52:43,441 DAVID J. MALAN: Ah. 1100 00:52:43,441 --> 00:52:46,542 So it looks pretty much like the image we had earlier 1101 00:52:46,542 --> 00:52:48,500 with a bunch of black chips here, each of which 1102 00:52:48,500 --> 00:52:51,250 store some number of megabytes or gigabytes probably. 1103 00:52:51,250 --> 00:52:54,000 And then the little gold pin, so to speak, that could actually get 1104 00:52:54,000 --> 00:52:54,420 plugged in. 1105 00:52:54,420 --> 00:52:55,720 And they can only go a certain way. 1106 00:52:55,720 --> 00:52:58,320 In fact, I've done this blindly before where I've accidentally 1107 00:52:58,320 --> 00:53:01,320 plugged it in the wrong way, only to realize, it actually goes this way. 1108 00:53:01,320 --> 00:53:03,895 And that's why this little divot here is asymmetric. 1109 00:53:03,895 --> 00:53:04,770 COLTON OGDEN: Indeed. 1110 00:53:04,770 --> 00:53:06,940 DAVID J. MALAN: I'm done with this, doctor. 1111 00:53:06,940 --> 00:53:07,440 OK. 1112 00:53:07,440 --> 00:53:08,370 We're not going to put that back in. 1113 00:53:08,370 --> 00:53:10,500 And what's this big thing in the back of a PC? 1114 00:53:10,500 --> 00:53:12,677 COLTON OGDEN: So this is the Power Supply or PSU. 1115 00:53:12,677 --> 00:53:15,760 It essentially just powers everything up with electricity in the computer. 1116 00:53:15,760 --> 00:53:16,100 DAVID J. MALAN: I see. 1117 00:53:16,100 --> 00:53:18,630 And so if this is the extent to which you've actually 1118 00:53:18,630 --> 00:53:21,338 played with the inside of your computer before-- this, of course, 1119 00:53:21,338 --> 00:53:22,381 is the power cable. 1120 00:53:22,381 --> 00:53:25,380 And this is actually a standardized plug that goes back into the device. 1121 00:53:25,380 --> 00:53:28,160 You can actually use this or any number of other cables on your own computer. 1122 00:53:28,160 --> 00:53:28,610 COLTON OGDEN: Indeed. 1123 00:53:28,610 --> 00:53:28,770 DAVID J. MALAN: All right. 1124 00:53:28,770 --> 00:53:31,890 So where is my data stored when not in RAM persistently? 1125 00:53:31,890 --> 00:53:35,470 COLTON OGDEN: When not in RAM, you have, here, an external Hard Drive, an HDB, 1126 00:53:35,470 --> 00:53:37,220 or an internal hard drive in this context. 1127 00:53:37,220 --> 00:53:38,011 DAVID J. MALAN: OK. 1128 00:53:38,011 --> 00:53:41,641 So this is older and bigger probably than something like an SSD? 1129 00:53:41,641 --> 00:53:42,390 COLTON OGDEN: Yes. 1130 00:53:42,390 --> 00:53:47,879 Older and larger, but probably stores less since this is an older computer. 1131 00:53:47,879 --> 00:53:50,920 And it's connected to the motherboard using what's called the SATA cable, 1132 00:53:50,920 --> 00:53:52,860 S-A-T-A, which hooks right into the motherboard. 1133 00:53:52,860 --> 00:53:53,190 DAVID J. MALAN: Oh, yeah. 1134 00:53:53,190 --> 00:53:55,510 Can we can we pull that out without that much damage here? 1135 00:53:55,510 --> 00:53:55,900 COLTON OGDEN: Yeah. 1136 00:53:55,900 --> 00:53:56,399 Absolutely. 1137 00:53:56,399 --> 00:53:59,429 So it's a pretty small cable, it plugs right into the motherboard there. 1138 00:53:59,429 --> 00:54:00,220 DAVID J. MALAN: Ah. 1139 00:54:00,220 --> 00:54:00,855 OK. 1140 00:54:00,855 --> 00:54:05,280 So it's got kind of a nice angled shape so that it only goes, in it would seem, 1141 00:54:05,280 --> 00:54:05,990 one way. 1142 00:54:05,990 --> 00:54:06,490 All right. 1143 00:54:06,490 --> 00:54:08,400 And actually, it looks like a different type of cable 1144 00:54:08,400 --> 00:54:09,660 is used for this older technology. 1145 00:54:09,660 --> 00:54:11,530 We seem to have another DVD or CD drive up there? 1146 00:54:11,530 --> 00:54:12,000 COLTON OGDEN: We do. 1147 00:54:12,000 --> 00:54:12,500 We do. 1148 00:54:12,500 --> 00:54:14,520 We have a DVD drive. 1149 00:54:14,520 --> 00:54:16,350 And actually it does you SATA as well. 1150 00:54:16,350 --> 00:54:16,762 DAVID J. MALAN: Oh, Yes. 1151 00:54:16,762 --> 00:54:18,280 COLTON OGDEN: It plugs right in with the hard drives. 1152 00:54:18,280 --> 00:54:18,560 DAVID J. MALAN: Oh. 1153 00:54:18,560 --> 00:54:20,750 But it has a special power cable that drives that. 1154 00:54:20,750 --> 00:54:21,500 COLTON OGDEN: Yep. 1155 00:54:21,500 --> 00:54:21,630 Exactly. 1156 00:54:21,630 --> 00:54:23,796 DAVID J. MALAN: --just like the hard drive does too. 1157 00:54:23,796 --> 00:54:26,350 So actually, we have, in advance, taken apart 1158 00:54:26,350 --> 00:54:30,175 and 3.5 inch mechanical hard drive that you previously 1159 00:54:30,175 --> 00:54:32,550 had a whole bunch of screws on it and probably previously 1160 00:54:32,550 --> 00:54:34,202 had a whole bunch of data on it. 1161 00:54:34,202 --> 00:54:35,910 But now that we've exposed it to the air, 1162 00:54:35,910 --> 00:54:38,400 and therefore all of the dust particles here in the theater, 1163 00:54:38,400 --> 00:54:40,358 probably not going to be very reliable anymore. 1164 00:54:40,358 --> 00:54:43,980 But what's really cool now is that we took off all but one of the screws 1165 00:54:43,980 --> 00:54:48,190 so we can actually pull this off. 1166 00:54:48,190 --> 00:54:52,870 And you can see what's been inside your own hard drive perhaps all this time. 1167 00:54:52,870 --> 00:54:55,380 So this is, again, is 3 and 1/2 inches across, 1168 00:54:55,380 --> 00:54:58,980 which is a standard size, at least, for these older larger mechanical drives. 1169 00:54:58,980 --> 00:55:01,830 There's also a 2.5 inch version of this commonly found in laptops 1170 00:55:01,830 --> 00:55:04,320 or even higher-end desktops these days. 1171 00:55:04,320 --> 00:55:07,170 And there's that mechanical arm that won't move now because there's 1172 00:55:07,170 --> 00:55:08,520 no power going into this. 1173 00:55:08,520 --> 00:55:11,670 But if there were, we'd be plugging it in to the back of the device 1174 00:55:11,670 --> 00:55:15,330 here and then that SATA cable, which actually runs the power. 1175 00:55:15,330 --> 00:55:19,140 And how many-- it looks like there's two platters here. 1176 00:55:19,140 --> 00:55:19,710 Two platters. 1177 00:55:19,710 --> 00:55:22,110 So the data store probably on the top, on the bottom, 1178 00:55:22,110 --> 00:55:24,176 and then on the other top, and the other bottom, 1179 00:55:24,176 --> 00:55:25,800 thereby fitting even more data in here. 1180 00:55:25,800 --> 00:55:27,660 And if this were an even newer bigger hard drive, 1181 00:55:27,660 --> 00:55:30,360 we could probably fit even more platters, and therefore more data. 1182 00:55:30,360 --> 00:55:33,090 And increasingly, is the data being stored closer and closer together, 1183 00:55:33,090 --> 00:55:35,790 so all those magnetic particles are packed ever more densely, 1184 00:55:35,790 --> 00:55:37,890 which also means we can store more bits and thus 1185 00:55:37,890 --> 00:55:40,181 bytes and thus files and programs. 1186 00:55:40,181 --> 00:55:40,680 All right. 1187 00:55:40,680 --> 00:55:43,390 So what we also have here a motherboard. 1188 00:55:43,390 --> 00:55:46,000 Can we take a closer look at this outside of the box? 1189 00:55:46,000 --> 00:55:47,125 COLTON OGDEN: Yes. 1190 00:55:47,125 --> 00:55:49,500 DAVID J. MALAN: So this one looks a little bit different. 1191 00:55:49,500 --> 00:55:51,840 And, in fact, I don't see a CPU. 1192 00:55:51,840 --> 00:55:52,889 Where's our CPU gone? 1193 00:55:52,889 --> 00:55:54,930 COLTON OGDEN: Well, this one does not have a CPU. 1194 00:55:54,930 --> 00:55:56,221 It's been taken out in advance. 1195 00:55:56,221 --> 00:55:58,740 But most of the other components are still in place here. 1196 00:55:58,740 --> 00:56:02,111 We have RAM, we have a heat sink, and we have a lot of other ports 1197 00:56:02,111 --> 00:56:04,860 and such that we've seen on the other motherboard and was looking. 1198 00:56:04,860 --> 00:56:07,170 DAVID J. MALAN: And these internal ports, what gets plugged into those? 1199 00:56:07,170 --> 00:56:08,850 COLTON OGDEN: So these are PCI slots. 1200 00:56:08,850 --> 00:56:11,880 You'll see oftentimes graphics cards, sound cards-- 1201 00:56:11,880 --> 00:56:15,180 other things that aren't necessarily always with a computer, 1202 00:56:15,180 --> 00:56:17,639 but are optional-- those get plugged into these ports here. 1203 00:56:17,639 --> 00:56:20,846 DAVID J. MALAN: And it looks like if we plug this into the back of a computer 1204 00:56:20,846 --> 00:56:23,820 just right, these things should stick out the back of the plastic case? 1205 00:56:23,820 --> 00:56:24,150 COLTON OGDEN: Yes. 1206 00:56:24,150 --> 00:56:26,340 These are ports that are often user-facing, 1207 00:56:26,340 --> 00:56:31,530 so you can plug-in peripherals such as keyboards, mice, 1208 00:56:31,530 --> 00:56:36,450 monitors with VGA ports, maybe headphones or speakers with these ports 1209 00:56:36,450 --> 00:56:40,719 here, headphones, microphones line out, and a few other ports, maybe-- 1210 00:56:40,719 --> 00:56:43,760 DAVID J. MALAN: Do you want to talk to them in some of these older ports? 1211 00:56:43,760 --> 00:56:44,980 These are really from my day. 1212 00:56:44,980 --> 00:56:46,813 So the parallel port, which is where we used 1213 00:56:46,813 --> 00:56:49,320 to put our printers or serial ports-- 1214 00:56:49,320 --> 00:56:51,820 I don't know what voice that is-- but our serial ports where 1215 00:56:51,820 --> 00:56:55,930 we used to put our joysticks for playing the games, a VGA port, of course, 1216 00:56:55,930 --> 00:56:59,410 and then a whole bunch of USB ports there, which we can actually 1217 00:56:59,410 --> 00:57:00,670 take a closer look at a cable. 1218 00:57:00,670 --> 00:57:03,460 So here's a common end of a USB cable. 1219 00:57:03,460 --> 00:57:06,640 This is Type A, and so that's probably the most common type. 1220 00:57:06,640 --> 00:57:09,757 But the white plastic on the inside suggests that this is an older cable. 1221 00:57:09,757 --> 00:57:11,590 If you look at newer cables, you'll actually 1222 00:57:11,590 --> 00:57:14,560 see that the inside is blue, which means its USB 3.0, which generally 1223 00:57:14,560 --> 00:57:17,530 means faster, which means you can move data back and forth all the more 1224 00:57:17,530 --> 00:57:18,190 quickly. 1225 00:57:18,190 --> 00:57:20,440 But on the other ends of these USB cables-- 1226 00:57:20,440 --> 00:57:22,330 you see, like the Type B connector here-- 1227 00:57:22,330 --> 00:57:26,160 this is commonly found in the back of a printer or a scanner. 1228 00:57:26,160 --> 00:57:27,865 So it's a slightly different plug. 1229 00:57:27,865 --> 00:57:30,140 It keeps one end straight from the other. 1230 00:57:30,140 --> 00:57:32,740 But you will actually see sometimes smaller cables 1231 00:57:32,740 --> 00:57:35,410 like this one here, mini or micro USB, commonly 1232 00:57:35,410 --> 00:57:37,750 found on phones or just smaller devices where 1233 00:57:37,750 --> 00:57:40,446 it would be annoying to try to plug-in something as big as this. 1234 00:57:40,446 --> 00:57:42,820 Well, I think we have just a couple of other things here. 1235 00:57:42,820 --> 00:57:44,662 Here we have-- this came from a computer. 1236 00:57:44,662 --> 00:57:46,870 No CPU attached, but this is one of those heat sinks? 1237 00:57:46,870 --> 00:57:47,430 You were talking about? 1238 00:57:47,430 --> 00:57:48,263 COLTON OGDEN: It is. 1239 00:57:48,263 --> 00:57:50,620 It's a combo of a heat sink and a fan for a CPU. 1240 00:57:50,620 --> 00:57:51,536 DAVID J. MALAN: I see. 1241 00:57:51,536 --> 00:57:54,440 So Intel Inside might also mean you have an Intel fan, it would seem, 1242 00:57:54,440 --> 00:57:55,090 and heat sink. 1243 00:57:55,090 --> 00:57:58,510 And then lastly, we've got one of these things here. 1244 00:57:58,510 --> 00:57:59,440 What's this here? 1245 00:57:59,440 --> 00:58:01,398 COLTON OGDEN: This is a solid state hard drive, 1246 00:58:01,398 --> 00:58:06,370 which actually uses flash memory very akin to microSDs, if you're familiar. 1247 00:58:06,370 --> 00:58:08,290 It's essentially what a hard drive is. 1248 00:58:08,290 --> 00:58:11,290 But instead of having a movable mechanical arm that 1249 00:58:11,290 --> 00:58:14,700 looks at the different bits on the platters, as we talked about, 1250 00:58:14,700 --> 00:58:15,670 it's almost like RAM. 1251 00:58:15,670 --> 00:58:18,790 It's just storing the data in electricity, 1252 00:58:18,790 --> 00:58:20,397 hence solid state, no moving parts. 1253 00:58:20,397 --> 00:58:21,730 DAVID J. MALAN: But permanently. 1254 00:58:21,730 --> 00:58:22,646 COLTON OGDEN: But yes. 1255 00:58:22,646 --> 00:58:24,610 It's nonvolatile, which means, unlike RAM, you 1256 00:58:24,610 --> 00:58:27,640 can actually store this whether or not you turn your laptop off or whatever. 1257 00:58:27,640 --> 00:58:28,150 DAVID J. MALAN: All right. 1258 00:58:28,150 --> 00:58:29,858 And it looks like-- and I'm told I've got 1259 00:58:29,858 --> 00:58:32,720 to be extra careful with this-- this is a 4 terabyte SSD. 1260 00:58:32,720 --> 00:58:35,600 So this is a huge amount of data, 4 trillion bytes. 1261 00:58:35,600 --> 00:58:38,350 So we're just going to put this safely over here. 1262 00:58:38,350 --> 00:58:40,770 Less expensively, though, we have this little USB stick. 1263 00:58:40,770 --> 00:58:43,057 It's still 128 gigabytes, but it's a little gimmicky. 1264 00:58:43,057 --> 00:58:44,890 But this thing slides out here, and then you 1265 00:58:44,890 --> 00:58:47,470 can plug it into your laptop or desktop or really any device. 1266 00:58:47,470 --> 00:58:49,345 And it's a really convenient way, ultimately, 1267 00:58:49,345 --> 00:58:52,100 just like moving files back and forth between each other. 1268 00:58:52,100 --> 00:58:52,600 All right. 1269 00:58:52,600 --> 00:58:54,010 Well, Dr. Ogden, thank you so much. 1270 00:58:54,010 --> 00:58:57,218 I'm sure you're going to want to take care of putting this all back together. 1271 00:58:57,218 --> 00:58:59,430 And this was hardware. 1272 00:58:59,430 --> 00:59:03,266