WEBVTT - Hard Disk Drives vs Solid State Drives 0:00:04.400 --> 0:00:07.800 Welcome to text Stuff, a production from my Heart Radio. 0:00:12.320 --> 0:00:15.319 Hey there, and welcome to tech Stuff. I'm your host, 0:00:15.480 --> 0:00:19.000 Jonathan Strickland. I'm an executive producer with I Heart Radio 0:00:19.120 --> 0:00:22.680 and I love all things tech and I recently had 0:00:22.760 --> 0:00:25.560 a couple of listeners right to me and ask if 0:00:25.560 --> 0:00:28.960 I could do an episode about solid state drives, which 0:00:29.040 --> 0:00:31.840 is a method of data storage. So today we're going 0:00:31.880 --> 0:00:34.839 to learn about different ways to store information with computer 0:00:34.920 --> 0:00:39.960 systems and what makes each one special. And there are 0:00:40.000 --> 0:00:43.360 a lot of different ways that computer scientists have created 0:00:43.400 --> 0:00:48.839 to store information, either temporarily or you know, permanently or 0:00:48.920 --> 0:00:52.680 semi permanently using computer systems. To go through all of 0:00:52.720 --> 0:00:55.960 them and to explain how all of them work would 0:00:55.960 --> 0:00:58.680 actually take a few episodes. A lot of them work 0:00:58.680 --> 0:01:03.880 in similar ways but with different manifestations. And also a 0:01:03.920 --> 0:01:06.640 lot of those methods are actually totally obsolete today, so 0:01:06.880 --> 0:01:09.679 we're not gonna go over everything. Instead, we're going to 0:01:10.040 --> 0:01:14.319 have a quick refresher on ROM, RAM, cash memory, and 0:01:14.360 --> 0:01:18.440 then storage systems. ROM and RAM are both types of 0:01:18.560 --> 0:01:22.039 computer memory. The purpose of computer memory is to have 0:01:22.120 --> 0:01:25.880 a way to reference instructions quickly to run processes, and 0:01:25.920 --> 0:01:28.600 by that I mean for the CPU to be able 0:01:28.640 --> 0:01:31.280 to get to the information it needs. Typically, we refer 0:01:31.360 --> 0:01:34.240 to memory as being a type of data storage that 0:01:34.280 --> 0:01:38.399 a CPU can access directly, as opposed to permanent storage, 0:01:38.760 --> 0:01:42.080 which must be retrieved before the CPU can access it. 0:01:42.440 --> 0:01:46.119 A processor needs two major things to carry out tasks. 0:01:46.560 --> 0:01:50.040 It needs a list of instructions also known as what 0:01:50.360 --> 0:01:54.160 to do, and then data that's the stuff you're performing 0:01:54.160 --> 0:02:00.240 operations upon. So with an absurdly simple analogy, it would 0:02:00.280 --> 0:02:03.280 be like a teacher telling a student, Hey, I'm going 0:02:03.320 --> 0:02:05.600 to give you some numbers, and I want you to 0:02:05.720 --> 0:02:10.760 add those numbers together. So the student already knows the instructions, right, 0:02:11.000 --> 0:02:13.520 They know that they are to add any numbers that 0:02:13.600 --> 0:02:16.480 the teacher gives them. Then the teacher gives a list 0:02:16.520 --> 0:02:19.440 of numbers, which would be the data in our example, 0:02:19.760 --> 0:02:22.920 and the student would carry out the instructions adding them. 0:02:23.120 --> 0:02:26.600 Computer processors do something similar, though at a speed and 0:02:26.680 --> 0:02:29.680 level of complexity that's a little harder for us to grasp. 0:02:29.840 --> 0:02:33.280 But without memory, the processor has nothing to draw upon 0:02:33.600 --> 0:02:39.240 to actually do anything. Wrong. Stands for read only memory, 0:02:39.639 --> 0:02:43.080 and as the name suggests, this is memory that the 0:02:43.080 --> 0:02:47.560 computer can reference, but it doesn't change it or add 0:02:47.600 --> 0:02:51.000 to it, at least not under normal circumstances. There's some 0:02:51.240 --> 0:02:54.880 extreme exceptions, but we're not really going to get into 0:02:54.919 --> 0:02:57.679 them here. So you can think of this like messages 0:02:57.680 --> 0:03:00.440 that have been etched in stone, but you lack the 0:03:00.480 --> 0:03:03.799 ability or the tools to carve in anything into stone. 0:03:03.880 --> 0:03:07.320 So you can read these messages that already exist, but 0:03:07.400 --> 0:03:11.440 you can't change them in any way. Typically, read only 0:03:11.480 --> 0:03:15.320 memory contains basic instructions that a computer system needs in 0:03:15.440 --> 0:03:17.960 order for all of its components to work together and 0:03:18.040 --> 0:03:21.400 to boot up. So for a computer to actually be 0:03:21.560 --> 0:03:26.800 able to detect and interact with the various components the 0:03:26.840 --> 0:03:31.240 physical hardware that make up the computer. That's a necessary 0:03:31.320 --> 0:03:34.280 part of ROM, and it really is just a basic 0:03:34.320 --> 0:03:37.240 set of instructions that allow everything else to happen, like 0:03:37.360 --> 0:03:42.080 going through the initial process of recognizing inputting output devices. 0:03:42.120 --> 0:03:46.160 Without those instructions, the computer wouldn't do anything meaningful. It 0:03:46.200 --> 0:03:49.000 would just be a bunch of pieces that don't actually 0:03:49.040 --> 0:03:54.320 work together. RAM or random access memory, is kind of 0:03:54.360 --> 0:03:58.080 like short term memory for humans. This is where a 0:03:58.080 --> 0:04:01.600 computer can store information that's elevant to whatever the computer 0:04:01.680 --> 0:04:05.480 is doing at that very moment. So if you're running 0:04:05.480 --> 0:04:09.480 a program, a computer will load relevant data in RAM 0:04:09.520 --> 0:04:13.560 for quick reference. It's kind of like how I write episodes. 0:04:13.920 --> 0:04:16.400 I take a lot of notes and then I've got 0:04:16.440 --> 0:04:19.480 my notes to refer to when i need to, you know, 0:04:19.839 --> 0:04:25.760 reference something. Accessing RAM is fast generally speaking, though there 0:04:25.800 --> 0:04:29.840 are some potential bottlenecks. I'll mention those late in this episode. 0:04:30.600 --> 0:04:33.920 But what does the random access part of RAM mean? 0:04:34.680 --> 0:04:37.839 It means that the processor can access the data on 0:04:37.880 --> 0:04:42.040 a RAM chip wherever that data might be physically stored 0:04:42.240 --> 0:04:45.560 on that chip, and that accessing any part of the 0:04:45.600 --> 0:04:48.720 memory should generally take the same amount of time regardless 0:04:48.760 --> 0:04:52.320 of where the data is stored. In contrast, there are 0:04:52.320 --> 0:04:54.960 some types of storage that would require a computer to 0:04:55.080 --> 0:04:58.960 scan through all the data recorded from the beginning of 0:04:59.000 --> 0:05:02.520 the storage until hill it hits the relevant patch of information. 0:05:03.240 --> 0:05:05.719 It's kind of like the difference between using a chapter 0:05:05.880 --> 0:05:09.239 select on a DVD or Blu Ray or just fast 0:05:09.279 --> 0:05:11.920 forward scrubbing through a movie to get to a specific scene. 0:05:12.360 --> 0:05:14.799 If you have a DVD or Blue ray that has chapters, 0:05:15.120 --> 0:05:18.440 you can just jump right to the relevant section and 0:05:18.480 --> 0:05:23.320 you access that specific part of the story instantly. Without chapters, 0:05:23.760 --> 0:05:26.520 then you have to go through the whole movie sequentially 0:05:26.640 --> 0:05:29.640 to get to the part you actually want. RAM is 0:05:29.680 --> 0:05:34.240 more like the chapter select approach. RAM has a limited capacity. 0:05:34.560 --> 0:05:36.600 Now this depends on the type of RAM you've got 0:05:36.600 --> 0:05:41.080 installing your PC or your computational device. Some machines, like 0:05:41.360 --> 0:05:43.920 a lot of PCs, are designed in such a way 0:05:44.040 --> 0:05:46.719 that you can upgrade RAM over time. You can add 0:05:46.880 --> 0:05:51.719 to it and create greater RAM capacity. But even upgraded, 0:05:52.000 --> 0:05:54.520 there will be a limit as to how much data 0:05:54.640 --> 0:05:58.400 can exist in RAM at any given time. You can't 0:05:58.600 --> 0:06:03.279 just keep updating RAM forever. Motherboards won't accept that. Processors 0:06:03.279 --> 0:06:06.719 can't work with it, so there are actual limitations that 0:06:06.760 --> 0:06:11.719 are dependent upon outside factors. Even with upgraded RAM, there 0:06:11.839 --> 0:06:14.000 is a limit to how much data can exist in 0:06:14.120 --> 0:06:17.000 RAM all at a given time. You can't load every 0:06:17.040 --> 0:06:20.320 single thing from storage into RAM. It wouldn't make sense 0:06:20.560 --> 0:06:22.919 for me to copy all of my sources word for 0:06:22.960 --> 0:06:26.599 word in my notes, right because then my notes aren't 0:06:26.600 --> 0:06:29.920 notes anymore. They are copies of the original sources, and 0:06:29.920 --> 0:06:32.560 I wouldn't really be able to refer to them very quickly. 0:06:33.440 --> 0:06:37.039 RAM is also temporary, by which I mean that the 0:06:37.160 --> 0:06:40.440 data that is inside RAM only sticks around for as 0:06:40.480 --> 0:06:44.880 long as the device is powered. Computer systems dump the 0:06:44.920 --> 0:06:49.240 information and RAM whenever the computer shuts down or restarts, 0:06:49.279 --> 0:06:53.080 so effectively the memory gets white. RAM is thus a 0:06:53.160 --> 0:06:56.520 type of volatile memory that means it works as long 0:06:56.560 --> 0:06:59.159 as the power is going to the system. You need 0:06:59.200 --> 0:07:01.760 a non volu a toll form of memory, something that's 0:07:01.800 --> 0:07:05.320 a more persistent, permanent method to store data in larger 0:07:05.400 --> 0:07:07.600 volumes if you want to be able to access it 0:07:07.960 --> 0:07:12.920 in subsequent sessions. ROM is non volatile, but then again, 0:07:12.920 --> 0:07:16.600 it's also unchangeable, so that doesn't do you any good either. 0:07:16.680 --> 0:07:19.240 You need something that you can actually update that is 0:07:19.280 --> 0:07:21.480 also non volatile if you want to be able to 0:07:21.520 --> 0:07:26.800 hold onto data between sessions. Before I move on to that, though, 0:07:27.040 --> 0:07:30.400 I should also mention cash memory c a c ch 0:07:30.520 --> 0:07:36.280 E memory. This allows processors to access specific, frequently referred 0:07:36.320 --> 0:07:41.000 to data at very fast speeds, faster than RAM. It 0:07:41.040 --> 0:07:44.800 has less capacity for storage than RAM does, but it 0:07:44.800 --> 0:07:46.920 can hold stuff that the processor is going to need 0:07:46.960 --> 0:07:49.960 to refer to a lot in order to complete whatever 0:07:49.960 --> 0:07:53.400 the task at hand happens to be. RAM capacity tends 0:07:53.440 --> 0:07:56.040 to be in the gigabyte range these days, but CASH 0:07:56.080 --> 0:07:58.760 tends to be much lower, like in the megabyte range, 0:07:59.280 --> 0:08:03.080 and just for the purposes of clarity, A byte is 0:08:03.120 --> 0:08:06.200 a unit of information that's equal to eight bits, and 0:08:06.280 --> 0:08:09.559 a bit is a piece of binary information a zero 0:08:09.760 --> 0:08:13.840 or a one. A megabyte is essentially one million bytes, 0:08:13.920 --> 0:08:18.040 and a gigabyte is essentially one billion bytes. A terabyte 0:08:18.080 --> 0:08:21.720 is essentially one trillion bytes. If you were to look 0:08:21.760 --> 0:08:24.960 at a computer motherboard, you would see the CPU or 0:08:25.040 --> 0:08:28.920 central processing unit, which is what executes the programs, and 0:08:29.000 --> 0:08:32.560 physically closest to the CPU would be the cash memory, 0:08:32.720 --> 0:08:35.520 which holds data that's going to be referenced frequently by 0:08:35.559 --> 0:08:39.360 the CPU. Next would be the RAM, So the CPU 0:08:39.400 --> 0:08:42.200 would check for information in cash memory first to see 0:08:42.200 --> 0:08:44.520 if it's there. If not, it would send a fetch 0:08:44.520 --> 0:08:47.560 request for information stored in RAM to see if it's there. 0:08:48.200 --> 0:08:50.320 And if the data isn't there, then the CPU has 0:08:50.360 --> 0:08:52.480 to send out a request to fetch data from non 0:08:52.600 --> 0:08:57.040 volatile storage. Non Volatile memory is necessary if you want 0:08:57.080 --> 0:09:00.240 to save data for longer than the immediate present. The 0:09:00.280 --> 0:09:03.520 tradeoff is it takes a processor a little bit longer 0:09:03.600 --> 0:09:07.600 to access that data. So in my notes example, let's 0:09:07.640 --> 0:09:10.000 say that I'm doing this episode and there's something I 0:09:10.040 --> 0:09:12.280 wanted to talk about, but I didn't write it down 0:09:12.280 --> 0:09:15.240 in my notes. I do happen to know, however, that 0:09:15.320 --> 0:09:18.520 it's in one of the large, dusty books that surround 0:09:18.559 --> 0:09:22.200 me at all times. I am cursed with them. So 0:09:22.440 --> 0:09:24.400 I would take a book aside, and then I would 0:09:24.400 --> 0:09:27.079 start searching through the book to find the relevant information. 0:09:27.240 --> 0:09:29.520 And this takes a bit longer than just glancing at 0:09:29.520 --> 0:09:32.160 my notes would. And that's kind of what it's like 0:09:32.240 --> 0:09:35.400 for a computer to reference information that's stored on a 0:09:35.480 --> 0:09:39.160 hard drive or solid state drive. When I was growing up, 0:09:39.400 --> 0:09:43.120 my family's first real computer was an Apple to Eat, 0:09:43.240 --> 0:09:46.600 and that computer did not have a hard drive. Instead, 0:09:47.080 --> 0:09:50.040 you would save information onto five and a quarter inch 0:09:50.240 --> 0:09:53.880 floppy disc ets the computer had a disk drive. You 0:09:53.880 --> 0:09:56.640 would slide the floppy disk into the disk drive and 0:09:56.679 --> 0:09:59.280 then you could access whatever information was stored on it, 0:09:59.400 --> 0:10:02.600 or you could save information to it. If the computer 0:10:02.640 --> 0:10:05.560 needed to reference something from the disk, everything would be 0:10:05.600 --> 0:10:08.400 pretty much put on hold while the computer searched the 0:10:08.440 --> 0:10:12.079 disks contents for the specific information, then pull it up 0:10:12.160 --> 0:10:15.240 loaded into RAM, and then the computer program could continue. 0:10:15.679 --> 0:10:20.040 This process is particularly noticeable if you're running something really 0:10:20.200 --> 0:10:25.040 process or intensive like computer game. More complicated games such 0:10:25.080 --> 0:10:28.080 as those that have like really nice graphics, take up 0:10:28.120 --> 0:10:31.440 a lot of space. From a data perspective, the developers 0:10:31.440 --> 0:10:34.200 will typically design a game so that the computer running 0:10:34.240 --> 0:10:37.880 the game will load chunks of the game into its memory, 0:10:38.040 --> 0:10:41.480 but if you navigate to a new chunk, the computer 0:10:41.559 --> 0:10:45.120 has to reference the information in storage and then update everything, 0:10:45.160 --> 0:10:48.760 and that leads to the dreaded loading screen, and developers 0:10:48.760 --> 0:10:50.480 have found a lot of different ways to kind of 0:10:50.520 --> 0:10:52.880 deal with this. A common one was to put in 0:10:52.880 --> 0:10:55.480 a loading screen whenever you would go through a door 0:10:55.679 --> 0:10:59.120 that represented a major change of environment, such as if 0:10:59.120 --> 0:11:01.600 you were to go from the outside world of the 0:11:01.640 --> 0:11:05.200 game and enter the inside world, like going into a castle. 0:11:05.920 --> 0:11:08.720 Between being outside and inside, you know, when you would 0:11:08.760 --> 0:11:11.680 hit that door and you'd say open, you'd get treated 0:11:11.720 --> 0:11:14.680 to a loading screen. So part of what we're going 0:11:14.720 --> 0:11:17.720 to learn about today is why loading screens are even 0:11:17.760 --> 0:11:20.160 a thing and what type of storage results in different 0:11:20.160 --> 0:11:24.920 weight times. And let's start with hard disk drives a ka, 0:11:25.040 --> 0:11:29.439 the platter based drives. Alright, So back in the day, 0:11:29.559 --> 0:11:32.520 we used to store data on either floppy disks or 0:11:32.640 --> 0:11:35.800 hard disks. Although floppy disks are really a thing of 0:11:35.840 --> 0:11:38.520 the past at this point, unless you're using a truly 0:11:38.600 --> 0:11:43.080 old computer system, like a legacy computer system. Hard disks 0:11:43.120 --> 0:11:47.160 actually predate floppy disks, and we didn't call them hard 0:11:47.200 --> 0:11:51.040 disks originally because there was no floppy disk to refer to. 0:11:51.080 --> 0:11:53.679 You wouldn't call one without the other, right, there can 0:11:53.679 --> 0:11:56.960 be no good without evil. Well, originally we called these 0:11:57.160 --> 0:12:02.440 fixed disks, or sometimes we even were to them as Winchesters. 0:12:02.559 --> 0:12:04.640 And no, it wasn't a pair of brothers who went 0:12:04.679 --> 0:12:09.360 around attacking supernatural bad guys. In this case, the term 0:12:09.400 --> 0:12:14.240 Winchester actually came from IBM. It was IBM computer scientists 0:12:14.240 --> 0:12:18.320 who pioneered the design of the platter based hard drive 0:12:18.640 --> 0:12:22.760 back in the nineteen fifties, and the code name was Winchester. 0:12:23.440 --> 0:12:26.640 But then once floppy disks came along, folks would refer 0:12:26.720 --> 0:12:29.880 to fixed discs as hard disks. And then you had 0:12:29.880 --> 0:12:33.360 the differentiation. You had the floppy disks, which were external, 0:12:33.520 --> 0:12:35.280 then you would insert them into a drive and then 0:12:35.360 --> 0:12:37.840 remove them when you were done, and you had hard 0:12:37.840 --> 0:12:42.720 disks which stayed inside the computer. So hard disks are 0:12:43.040 --> 0:12:46.960 disc shaped there around with a hub or or hole 0:12:47.000 --> 0:12:52.560 in the middle, and they are contained within a sealed container, 0:12:53.000 --> 0:12:56.960 typically made of something like aluminum. And the reason why 0:12:57.240 --> 0:13:00.839 is because aluminum is a material that is non magnetic 0:13:01.160 --> 0:13:05.239 under normal conditions. If you went to truly extreme conditions, 0:13:05.760 --> 0:13:09.280 you could magnetize aluminum, but it would be well outside 0:13:09.640 --> 0:13:13.800 the conditions you would find someone's personal computer in. So 0:13:14.160 --> 0:13:17.560 old hard discs could only hold a few megabytes worth 0:13:17.559 --> 0:13:21.040 of data and they measured like twenty inches in diameter. 0:13:21.160 --> 0:13:24.080 They were huge, you know. The much later there would 0:13:24.080 --> 0:13:26.200 be closer to three and a half inches in diameter. 0:13:26.679 --> 0:13:30.760 So typically hard disk drives actually have stacks of discs. 0:13:30.800 --> 0:13:33.520 It's not just a single disc like a single platter, 0:13:33.840 --> 0:13:37.240 it's actually a stack of them, and each platter in 0:13:37.280 --> 0:13:41.400 that stack is separated by a small amount of space, 0:13:41.800 --> 0:13:46.040 so there's actually free space between each stack. If you 0:13:46.080 --> 0:13:47.800 think of one, two, and three, you've got a little 0:13:47.800 --> 0:13:51.400 bit of space between each of those. And that's really 0:13:51.440 --> 0:13:54.199 important and I'll get into that in a second. But 0:13:54.640 --> 0:13:58.840 floppy disks are a disc of thin plastic that has 0:13:58.880 --> 0:14:02.400 a coding of magnetic material on top of it, and 0:14:02.440 --> 0:14:07.920 the plastic disc is inside an envelope or disket made 0:14:08.000 --> 0:14:11.360 of thicker plastic and there have been several sizes of 0:14:11.360 --> 0:14:14.520 floppy discs over the years. There were eight inch discs, 0:14:14.600 --> 0:14:16.599 five and a quarter inch discs like my Apple to 0:14:16.720 --> 0:14:19.440 e had, and then three and a half inch diskts, 0:14:19.640 --> 0:14:24.080 which my IBM compatible computer used. The eight and the 0:14:24.080 --> 0:14:27.280 five and aquarre inch discs were pretty thin. They were 0:14:27.280 --> 0:14:30.880 made out of a thinner plastic material and that gave 0:14:31.440 --> 0:14:35.840 us the name floppy disc because they were flexible, though 0:14:36.720 --> 0:14:38.800 you were not supposed to bend them in any way 0:14:38.840 --> 0:14:41.840 that would possibly ruin everything. In fact, if you really 0:14:41.960 --> 0:14:45.720 bent it, you had just destroyed that disk. Uh. This 0:14:45.840 --> 0:14:47.960 was a piece of information that would have been useful 0:14:48.000 --> 0:14:50.440 to a lot of people back in the early eighties 0:14:50.480 --> 0:14:54.680 when they weren't aware that floppy did not mean you 0:14:54.680 --> 0:14:58.400 can fold it. But the terminology would become more confusing 0:14:58.480 --> 0:15:01.440 later on when three and a half inch discs, which 0:15:01.440 --> 0:15:04.240 are in a much thicker plastic case one that is 0:15:04.280 --> 0:15:08.960 not flexible, When those came around, it confused everything because 0:15:08.960 --> 0:15:11.160 those discs weren't floppy like the five and a quarter 0:15:11.280 --> 0:15:14.240 inch ones, So some folks would mistakenly refer to three 0:15:14.280 --> 0:15:17.600 and a half inch discs as hard disks, but they 0:15:17.600 --> 0:15:20.400 were still a type of external storage. You would insert 0:15:20.400 --> 0:15:22.640 a floppy disk into a disk drive, you would read 0:15:22.720 --> 0:15:24.640 or write to that disk, and then you could inject 0:15:24.720 --> 0:15:27.360 the disc and replace it with another one. And that's 0:15:27.360 --> 0:15:29.840 how our old Apple to E worked. If you were 0:15:29.840 --> 0:15:32.040 to write a page of text, you would save that 0:15:32.160 --> 0:15:35.880 page to a floppy disk for later retrieval because the 0:15:35.880 --> 0:15:39.360 computer had no way to store information on it permanently. 0:15:40.240 --> 0:15:44.160 Later on, c d s or compact discs would largely 0:15:44.200 --> 0:15:47.880 replace the need for floppy disks, particularly when computers began 0:15:47.920 --> 0:15:50.880 to include drives that could read or write to c 0:15:51.080 --> 0:15:53.840 d s. But by then we were also looking at 0:15:53.840 --> 0:15:56.440 computers that had internal storage in the form of a 0:15:56.520 --> 0:15:59.960 hard disk drive. And really the hard disk and floppy 0:16:00.080 --> 0:16:03.040 disk systems are fairly similar to each other, so rather 0:16:03.080 --> 0:16:06.040 than explain how each one works, I'll focus on hard 0:16:06.080 --> 0:16:08.720 disks so that we can contrast that with solid state 0:16:08.800 --> 0:16:12.280 drives in a little bit. Before we get into any 0:16:12.320 --> 0:16:23.200 of that, however, let's take a quick break. The first 0:16:23.240 --> 0:16:26.360 thing to get into our heads is that hard disk 0:16:26.520 --> 0:16:31.520 drives and floppy drives for that matter, are electro mechanical systems, 0:16:32.080 --> 0:16:35.480 so they have moving parts and if you were able 0:16:35.520 --> 0:16:39.000 to see through a computer, you know, Superman style, and 0:16:39.080 --> 0:16:41.120 you were able to see it's hard drive in motion. 0:16:41.640 --> 0:16:44.640 You might think it bears some resemblance to how a 0:16:44.800 --> 0:16:48.520 turntable plays the tracks on a vinyl record, And there 0:16:48.640 --> 0:16:53.640 is some similarity there, but only to a very superficial point. See, 0:16:53.840 --> 0:16:57.880 a vinyl record has physical grooves in it. The groove 0:16:58.000 --> 0:17:00.560 is a three dimensional groove with a little ridges and 0:17:00.680 --> 0:17:03.880 dips and edges, and the stylus or needle of the 0:17:03.920 --> 0:17:07.960 record player vibrates as it travels along this groove, and 0:17:07.960 --> 0:17:11.439 those vibrations passed to a piece of electric crystal or 0:17:11.440 --> 0:17:15.720 a tiny electromagnet, and that transforms the kinetic energy the 0:17:15.800 --> 0:17:20.119 energy get movement into electrical energy, and that electrical signal 0:17:20.240 --> 0:17:23.840 then passes on to amplifiers that boost that signal. That 0:17:23.920 --> 0:17:26.960 then goes on to speakers and it plays out as 0:17:27.000 --> 0:17:30.439 the sound that's on the record. Hard disc doesn't have 0:17:30.760 --> 0:17:34.440 a physical groove in it. Instead, it's a platter made 0:17:34.440 --> 0:17:38.680 out of something like ceramic glass or an aluminum alloy, 0:17:39.000 --> 0:17:42.240 and it has a mirror like finish. In fact, it's 0:17:42.320 --> 0:17:47.840 highly reflective. The disc has ferromagnetic particles bonded to it. 0:17:48.240 --> 0:17:52.159 These particles, if they are exposed to a magnetic field 0:17:52.200 --> 0:17:55.040 become magnetized themselves, and they will hold on to that 0:17:55.119 --> 0:17:58.840 magnetic property. So if you create a system where you 0:17:58.880 --> 0:18:04.000 give meaning to the specific magnetic orientation of domains of 0:18:04.080 --> 0:18:07.720 particles domains or sectors or regions of these particles on 0:18:07.760 --> 0:18:11.920 the platter, you can designate that as stuff like zeros 0:18:12.040 --> 0:18:15.200 and ones. For example, you could say that a domain 0:18:15.240 --> 0:18:18.600 that is magnetized so it aligns in the north direction 0:18:19.160 --> 0:18:21.560 is a one, and a domain that's aligned in the 0:18:21.680 --> 0:18:25.040 south direction is a zero. And then by applying a 0:18:25.080 --> 0:18:28.760 precise magnetic fluctuation to the domains, you could arrange them 0:18:28.800 --> 0:18:33.119 into meaningful representations of information. So with a hard disk drive, 0:18:33.560 --> 0:18:36.320 you do in fact have a disk, or more likely 0:18:36.600 --> 0:18:40.080 several disks or platters in a stack, and there is 0:18:40.119 --> 0:18:42.720 a hole or hub in the center of these disks, 0:18:43.240 --> 0:18:46.760 and those fit around a spindle. The spindle has a 0:18:46.800 --> 0:18:50.320 motor that can spend the disc super fast. I'll get 0:18:50.320 --> 0:18:52.679 into how fast in a second. Then you've got a 0:18:52.720 --> 0:18:56.480 mechanical arm and this has the little read right heads 0:18:56.680 --> 0:18:59.639 and those are transducers. These act kind of like the 0:18:59.720 --> 0:19:04.120 knee doll on a turntable, but there have their own 0:19:04.119 --> 0:19:07.520 special properties, and this arm can move from the inner 0:19:07.600 --> 0:19:09.399 edge of the disc to the outer edge in a 0:19:09.480 --> 0:19:12.119 fraction of a second. In fact, it would not be 0:19:12.200 --> 0:19:14.320 unusual to have one of these be able to move 0:19:14.440 --> 0:19:18.720 between those two edges fifty times per second. The arm 0:19:18.760 --> 0:19:22.919 itself is split so that the right head, as in 0:19:22.960 --> 0:19:25.479 the w R I T E head, the head that 0:19:25.600 --> 0:19:29.199 writes data to the disc, fits on one side of 0:19:29.200 --> 0:19:32.479 the platter, and the read head that reads information off 0:19:32.480 --> 0:19:35.320 the disc can fit on the other side of the platter. 0:19:35.600 --> 0:19:39.680 So the platter will spend between these two heads and 0:19:40.160 --> 0:19:44.080 they will be separated from that platter by just a tiny, tiny, 0:19:44.119 --> 0:19:46.960 tiny amount of space. This is one of those points 0:19:46.960 --> 0:19:50.520 where our vinyl record analogy really breaks down, because it 0:19:50.560 --> 0:19:53.119 would be like you would have a stylus or needle 0:19:53.280 --> 0:19:55.679 on either side of a record as it plays on 0:19:55.680 --> 0:19:59.239 the turntable, and that just doesn't happen. Now. Typically the 0:19:59.320 --> 0:20:03.159 arms motion controlled with electro magnets. Then you are likely 0:20:03.240 --> 0:20:05.800 dealing with a stack of discs, so you would also 0:20:05.840 --> 0:20:09.360 be working with a stack of read write heads mounted 0:20:09.400 --> 0:20:13.040 on this arm. You would have one pair of read 0:20:13.080 --> 0:20:17.280 write head transducers for every disc on the stack, and 0:20:17.320 --> 0:20:20.080 the arms would be separated like timees on a fork, 0:20:20.680 --> 0:20:23.879 so they can fit between those spinning disks, and it 0:20:23.920 --> 0:20:26.480 gets pretty snug in those hard drives. So if you 0:20:26.520 --> 0:20:28.959 had three platters in your hard drive, you would have 0:20:29.040 --> 0:20:32.760 six read right heads right, one read and one right 0:20:32.840 --> 0:20:36.639 head for each of the three platters. A transducer, by 0:20:36.640 --> 0:20:40.280 the way, is a type of electronic device that converts 0:20:40.520 --> 0:20:44.240 one form of energy into another form of energy, and 0:20:44.280 --> 0:20:46.960 there's a lot of stuff that falls into that category. 0:20:47.040 --> 0:20:50.960 It's a broad category. So a microphone has a transducer. 0:20:51.000 --> 0:20:55.040 It converts the kinetic energy from air pressure fluctuations a 0:20:55.160 --> 0:20:59.520 k a. Sound into electrical signals. A speaker does the 0:20:59.560 --> 0:21:02.400 same thing, but in the opposite direction. It takes electrical 0:21:02.440 --> 0:21:06.280 signals and converts those into kinetic energy by driving the 0:21:06.400 --> 0:21:09.480 diaphragm of a speaker to create fluctuations and air pressure, 0:21:09.640 --> 0:21:13.680 and we experience that a sound. A digital thermometer converts 0:21:13.720 --> 0:21:16.760 thermal energy into electrical energy, and then that can be 0:21:16.840 --> 0:21:21.879 measured and displayed on a little screen. The transducers in 0:21:21.920 --> 0:21:25.800 a hard disk drives read right head convert electrical energy 0:21:25.920 --> 0:21:29.840 into magnetic energy. The arm positions the read right head 0:21:29.880 --> 0:21:34.359 at a very specific point along the spinning platter, and 0:21:34.640 --> 0:21:37.480 those platters are spinning at like a hundred seventy miles 0:21:37.480 --> 0:21:41.120 per hour two d seventy two kilometers per hour. They 0:21:41.119 --> 0:21:44.119 could be spinning at a rate of thirty six hundred RPMs. 0:21:44.440 --> 0:21:47.320 Those are the old slow hard disk drives. If you 0:21:47.320 --> 0:21:53.360 can believe it, pms ten thousand revolutions per minute. It's 0:21:53.400 --> 0:21:56.200 incredible how fast they spend. And the transducer on these 0:21:56.240 --> 0:22:00.600 read right heads applies a magnetic fluctuation to that spinning disk, 0:22:01.160 --> 0:22:05.800 aligning magnetic particles either in a north or south orientation 0:22:05.880 --> 0:22:11.200 to indicate those ones and zeros recording information in binary data. Now, 0:22:11.200 --> 0:22:14.920 to read data, a transducer works more or less in reverse. 0:22:15.200 --> 0:22:18.400 The arm moves out to a certain distance from the 0:22:18.560 --> 0:22:21.560 edge of the disk as the disc spins up, and 0:22:21.600 --> 0:22:25.560 the moving magnetic particles traveling below the read right head 0:22:25.920 --> 0:22:29.320 induce an electrical signal to flow through the head, which 0:22:29.359 --> 0:22:32.640 then can be sent on to a processor. So instead 0:22:32.640 --> 0:22:37.280 of making a magnetic flux affect the platter, the actual 0:22:37.400 --> 0:22:41.560 magnetic field that is generated by the particles on the 0:22:41.600 --> 0:22:46.960 platter affect the transducer. It's a very elegant kind of solution. Now, 0:22:47.000 --> 0:22:49.680 The data on a hard disk falls into areas known 0:22:49.720 --> 0:22:52.960 as sectors and tracks. You can think of a track 0:22:53.400 --> 0:22:56.760 as a concentric circle, sort of like an archery target. 0:22:57.320 --> 0:22:59.680 These circles get larger as you get to the outer edge. 0:22:59.680 --> 0:23:02.760 It also means that they travel at a different speed. 0:23:03.040 --> 0:23:05.119 The outer edge of a record travels at a faster 0:23:05.240 --> 0:23:09.160 speed than the inner edge of a record, which doesn't 0:23:09.160 --> 0:23:10.840 seem to make sense at first because you think it's 0:23:10.840 --> 0:23:13.240 all rotating at the same rate. But you have to 0:23:13.240 --> 0:23:17.479 remember that outer edge represents a further distance, so the 0:23:17.520 --> 0:23:20.240 outer edge is going further in the same amount of 0:23:20.280 --> 0:23:23.119 time as the inner edge, which means it has to 0:23:23.160 --> 0:23:28.879 be traveling faster. So so sectors are like wedges within 0:23:29.000 --> 0:23:32.520 those concentric circles. If you think of the platter as 0:23:32.560 --> 0:23:35.959 like a pie, the sectors would be the slices of 0:23:36.040 --> 0:23:43.119 pie along these concentric circles. Mm hmm pie. Tracks are 0:23:43.240 --> 0:23:47.160 numbered with zero being the closest to the outermost edge 0:23:47.160 --> 0:23:50.280 of the disc, and then counting upward from there until 0:23:50.320 --> 0:23:52.040 you get all the way to the inner part of 0:23:52.080 --> 0:23:55.359 the disc. Sectors can hold a set number of bites, 0:23:55.400 --> 0:23:59.320 like five twelve bites. That's not very many bites. At all, 0:23:59.800 --> 0:24:02.679