Speaker 1: Welcome to tech Stuff, a production of I Heart Radios
Speaker 1: How Stuff Works. Hey there, and welcome to tech Stuff.
Speaker 1: I'm your host, Jonathan Strickland. I'm an executive producer with
Speaker 1: How Stuff Works and I Heart Radio and a love
Speaker 1: of all things tech and his time for another classic
Speaker 1: tech Stuff episode. This episode originally published on July two
Speaker 1: thousand twelve, just days after technology had been invented. This
Speaker 1: particular episode covers solid state drives, something that is far
Speaker 1: more common these days, was already, you know, fairly common
Speaker 1: back in two thousand twelve, but now it's becoming a
Speaker 1: standard feature and it's rare when you come across other
Speaker 1: types of hard drives in a lot of different technologies.
Speaker 1: So let's join past Jonathan Strickland and his co host
Speaker 1: Chris Palette and learn about solid state drives. Hey there,
Speaker 1: So today we wanted to talk a little bit about
Speaker 1: solid state drives and what makes them work and how
Speaker 1: they are different from the traditional forms of storage media
Speaker 1: that we are used to in the world of computers. Now,
Speaker 1: some of you out there may be used to solid
Speaker 1: state drives, and so you're thinking how our solid state
Speaker 1: drives different from other solid state drives. That's not what
Speaker 1: I mean. I mean those of us who have used
Speaker 1: hard disks that use magnetic storage in some form and
Speaker 1: uh there are a lot of differences, mainly mechanical physical differences,
Speaker 1: because when you're talking about a hard disk I gus
Speaker 1: a traditional hard hard disk drive, you're talking about a
Speaker 1: device that has moving parts and UM, it has platters
Speaker 1: that are that have information stored on the magnetically use
Speaker 1: magnetic fields to change uh informations into zeros and ones,
Speaker 1: those bits that we use to create the data that
Speaker 1: computers can understand. And you have a physical device that
Speaker 1: reads that information off of the platters. The players have
Speaker 1: to spin for this to happen. Uh. Turns out those
Speaker 1: devices they take up they take a lot of time
Speaker 1: to pull that information up relatively speaking. Right When I
Speaker 1: say a lot of time, we're talking milliseconds. But still, yeah,
Speaker 1: there are When you think about getting information into and
Speaker 1: out of uh your computers basically what you're doing right now,
Speaker 1: there there's several different ways it does that. There's uh,
Speaker 1: some information that is available for you know, ready retrieval. UM.
Speaker 1: You know in the cash that's built in you have
Speaker 1: level one, level two cash. You may not have necessarily
Speaker 1: known what that was. I didn't, uh, you know, and
Speaker 1: it's sort of uh, it's sort of intuitive when you
Speaker 1: think about it. It keeps it this information in this
Speaker 1: cash on hand. So stuff that you're doing right now
Speaker 1: is is kept right there close by in a very
Speaker 1: fast um uh, in a very fast retrieval system, so
Speaker 1: I can pull it back at at at a nanoseconds.
Speaker 1: Notice right, in fact, if we if we go, it's
Speaker 1: easy to imagine this if we think of the CPU first,
Speaker 1: just look at the central processing of your computer and
Speaker 1: think of that as this is the place where operations
Speaker 1: are executed upon data. Right. It pulls data in, it
Speaker 1: executes an operation on it, it gets a result. That's
Speaker 1: the purpose of the CPU. Now, a CPU has something
Speaker 1: called registers. Registers are where the CPU can hold data.
Speaker 1: But registers hold a very small amount of data comparatively speaking,
Speaker 1: usually just a few hundred bytes. You can build larger registers,
Speaker 1: and you can build more registers for your CPU, but
Speaker 1: that tends to be pretty expensive. Now, the benefit of
Speaker 1: having information and registers on the CPU is that you
Speaker 1: have next to no time at all between when you
Speaker 1: pull the information and when you can execute an operation
Speaker 1: upon that information. So that means that we say that
Speaker 1: the latency for the information within a CPUs registers is zero.
Speaker 1: Latency is that time between when you retrieve information and
Speaker 1: when you can or when you send a request for
Speaker 1: information and when you actually retrieve it. So there's no
Speaker 1: latency when you're talking about a the CPUs registers. However,
Speaker 1: only a few hundred bytes are exist within those registers.
Speaker 1: It's not a lot of data. Now you were talking
Speaker 1: about the cash is the level one cash is kind
Speaker 1: of the information that the CPU uses frequently. It's going
Speaker 1: to in whatever application you have to be in at
Speaker 1: that time, right, So this is information that the CPU
Speaker 1: is having to go to again and again, and it
Speaker 1: needs it to be as close as possible so that
Speaker 1: it keeps that latency down because of course, if you
Speaker 1: have to go further out for your information, it's going
Speaker 1: to take longer for it to get back. So at
Speaker 1: level one cash, you're talking about around bytes of data
Speaker 1: per CPU core. If you're running an ivy Bridge processor
Speaker 1: and I seven core ivy Bridge processor from Mentel, so
Speaker 1: that's three per UH core and as far as that
Speaker 1: level one cash goes, and that takes a nanosecond to
Speaker 1: pull that data up. So that's one billionth of a second. Yep.
Speaker 1: And uh, you know, just on the just to comment
Speaker 1: on the ivy bridge notation that the cash is themselves, Um,
Speaker 1: you know they exist on all these different processors. That's
Speaker 1: just that figure was just specific to the ivy bridge,
Speaker 1: But other processors do have this as well. Yes, yes,
Speaker 1: just in case there was any confusion. And then you
Speaker 1: could have a level to cash just slightly further out.
Speaker 1: You know, think of think of it like concentric circles, right,
Speaker 1: So the level two cash is a concentric circle further
Speaker 1: out from the CPU. It can hold a little more data.
Speaker 1: It's a little slower to pull that information up, it's
Speaker 1: a few nanoseconds. Then it may even have a level
Speaker 1: three cash. Not all CPUs do, but many do, and
Speaker 1: then that is even larger and holds even more data
Speaker 1: and takes even longer again in relative terms, to get
Speaker 1: that data to the CPU. And beyond that, that's when
Speaker 1: you go to your computer's actual memory, because all the
Speaker 1: stuff we've been talking about right now is all located
Speaker 1: on the CPU die itself, so it's all part of
Speaker 1: that that chip. Yeah, it's not you know, it's not separate.
Speaker 1: It's not another element that's on the motherboard. This is
Speaker 1: all part of the CPU. Yeah. If you if you
Speaker 1: pull your hard drive out of the computer toss it
Speaker 1: on the floor, don't don't do that. Um. And uh.
Speaker 1: And you you pull the the RAM chips out of
Speaker 1: your computer and toss them on the floor, don't do
Speaker 1: that either. Um. Then I'm glad you did that, because
Speaker 1: I was thinking it. It was just funny that you
Speaker 1: said it. Um. Then the the registry and the cashes
Speaker 1: will still be there on the computer and I won't
Speaker 1: be able to do a whole lot with them. But still, um,
Speaker 1: so you know that, just to illustrate that. So, yes,
Speaker 1: the next part will pick this stuff gently back up
Speaker 1: off the floor and put it inside. The RAM is
Speaker 1: essentially the next ring out if you will, from the
Speaker 1: cash is however many that you happen to have on
Speaker 1: your CPU, right, And these these memory chips have been
Speaker 1: optimized so that the latency is really really low. However,
Speaker 1: they are not located on the CPU. They are connected
Speaker 1: by circuits by by pathways to the CPU. Well, because
Speaker 1: they are not located on the CPU, and because that
Speaker 1: information does have to actually travel a physical distance, that
Speaker 1: increases the latency time. So when your CPU has to
Speaker 1: pull information out and that information is not in the
Speaker 1: cash for the CPU, it has to but it resides
Speaker 1: within the memory of your computer. Then it has to
Speaker 1: travel this pathway and for the request and retrieval that
Speaker 1: can take between forty an eighty nanoseconds. So we're still
Speaker 1: talking a fraction of a second. Yeah, I mean this
Speaker 1: is these are are times that you or I will
Speaker 1: not even be able to notice. Yeah, we can't. We
Speaker 1: we have no ability to to register that using our senses.
Speaker 1: We would have to use incredibly sensitive measurement devices in
Speaker 1: order to be able to tell the difference between forty
Speaker 1: and eighty nano seconds. To us, there's no meaningful difference
Speaker 1: at all. But the but the thing about RAM is
Speaker 1: when you shut off the computer, all that information that's
Speaker 1: in RAM. Yeah, it's it's held there by the electrical
Speaker 1: charge UM, which is relative to the computer. Now you're
Speaker 1: hard drive with the information stored we're talking traditional when
Speaker 1: the information stored man magnetically on those platters. Um, it's
Speaker 1: able to save that stuff so that when you turn
Speaker 1: the computer back on, you can read the hard drive
Speaker 1: and get it back. Um. The thing is that hard
Speaker 1: drives have different rotating speeds UM typical to see a
Speaker 1: laptop with a rpm uh drive or or even revolutions
Speaker 1: per minute just in case you aren't familiar with the
Speaker 1: term UM, and you're more likely to see fat those
Speaker 1: and faster in desktop computers UM and the faster these rotate.
Speaker 1: In general, that means the faster the information can be
Speaker 1: pulled from the hard drive and sent to memory and
Speaker 1: then onto your CPU. UM. So if you if you
Speaker 1: took your hard drive. The thing is that these systems
Speaker 1: are are delicate their their machine to very precise tolerances.
Speaker 1: That the head UM that reads the disc, it looks
Speaker 1: like it looks like a record player for those of
Speaker 1: us who remember that, But the the head doesn't actually
Speaker 1: touch the disc. If it does, that's what they call
Speaker 1: a bad thing. Yeah, it looks like it's in contact
Speaker 1: because it's so close to the platter, but in actuality
Speaker 1: there is like a millimeter's difference between where it is
Speaker 1: or even less. It's amazing, And that's the thing. If
Speaker 1: you did take your if you did take your hard
Speaker 1: drive and throw it on the floor, it is very
Speaker 1: possible that the head crashed into the platters, which is
Speaker 1: very bad right. If you ever hear a clicking noise
Speaker 1: from your hard drive, that usually means that the platters
Speaker 1: are out of alignment or that the head is actually
Speaker 1: coming into contact, something is hitting against something else within
Speaker 1: that physical mechanical device, and that means that it is
Speaker 1: breaking down. That that also means you should take that
Speaker 1: hard drive as soon as you can to a professional
Speaker 1: who can pull the data off of the hard drive,
Speaker 1: because the the hard drive itself may or may not
Speaker 1: be uh you may or may not be able to
Speaker 1: repair it. So you definitely want to be able to
Speaker 1: retrieve the information. And the reason why we're even talking
Speaker 1: about this physical device is because you may have guessed,
Speaker 1: because you've got this mechanical element, it's going to take
Speaker 1: a lot longer to retrieve that information. Comparatively speaking, we're
Speaker 1: talking about milliseconds now as opposed to nanoseconds, and in
Speaker 1: the world of computers, that's a long time. You know,
Speaker 1: a you're talking about these other fractions of a second,
Speaker 1: billions of a second, and then several or you know,
Speaker 1: you go to a couple orders of magnitude up you
Speaker 1: realize this is this is a lot longer, and it's
Speaker 1: going to mean that in general, the operations that you
Speaker 1: start to use on your computer are going to take
Speaker 1: more and more time. Well, there are only so many
Speaker 1: ways we can limit how much time it takes to
Speaker 1: retrieve information from a hard drive. Some of that includes
Speaker 1: creating better interfaces, which is when we went from the
Speaker 1: two SATA interfaces s A T A interfaces. Uh, that
Speaker 1: was actually a big improvement. It meant that we could
Speaker 1: move data much more quickly from the hard drive into RAM.
Speaker 1: But there's only so so much faster you can go
Speaker 1: without really turning up that RPM speed to ludicrous amounts.
Speaker 1: And of course the faster it goes, the more likely
Speaker 1: you have mechanical problems down the line. I mean we're
Speaker 1: in tear and things of that nature. So, Um, you
Speaker 1: have the incredibly reliable hard drive. I mean we've been
Speaker 1: using these things for years and years now. Um, they've
Speaker 1: gone up to very large sizes. Uh. And and they're
Speaker 1: they're fairly cheap compared to the way they were just
Speaker 1: a few years ago. But they have they have their
Speaker 1: own problems. I mean, they're they're delicate. You can't necessarily
Speaker 1: take them everywhere, um, you know, and expect them to operate. Uh. Flawlessly.
Speaker 1: Um and uh you know, as you pointed out, they're
Speaker 1: they're only so fast. So uh, flash memory in general
Speaker 1: is you know, an alternative, a very pleasant alternative. It
Speaker 1: works in our in our smartphones and our music players. UM,
Speaker 1: it works in in memory sticks, I mean d some drives.
Speaker 1: You know, kids of all ages now take them to
Speaker 1: school with them because you know that you can keep
Speaker 1: um I remember one gigabyte hard drives that were huge,
Speaker 1: and now you can keep sixteen gigs on a tiny
Speaker 1: thumb drive that cost you know, a very tiny fraction
Speaker 1: of the price. Spies, Spies use them to uh to
Speaker 1: put malware onto secure systems. Because both both stucks net
Speaker 1: and Flame appear to have been injected into target computers
Speaker 1: using UH and an offsite sort of storage device, So
Speaker 1: some sort of well offsite from the computer system. UH
Speaker 1: so something like a thumb drive. So you can imagine
Speaker 1: there's a guy who might have paid a little visit
Speaker 1: to an Iranian UH uranium enrichment plant and happened to
Speaker 1: have this thumb drive, plug it into a computer system
Speaker 1: and infected it that way. That's just one potential way
Speaker 1: that scenario could have unfolded. But yeah, I mean, these
Speaker 1: things have have become ubiquitous in all areas of computing,
Speaker 1: So why not a hard drive out of the same
Speaker 1: sort of approach, Because it means that you're using instead
Speaker 1: of a mechanical system, you're using an integrated circuit in
Speaker 1: order to store information. You no longer have to worry
Speaker 1: about spinning platters or reading heads or anything like that.
Speaker 1: You can really decrease the amount of time that that
Speaker 1: latency time, so that when you are pulling information from
Speaker 1: the hard drive, it's much closer to the speeds that
Speaker 1: you would see on the CPU die itself, or at
Speaker 1: least in the computer's memory, as opposed to on a
Speaker 1: traditional hard drive. And before we get too far into this,
Speaker 1: I do want to say something about what some of
Speaker 1: the sources of information we pulled from. We do have
Speaker 1: a great article on how stuff works about how flash
Speaker 1: drives work, and a lot of the information applies to
Speaker 1: solid state drives. Yeah they're not exactly the same, but yeah,
Speaker 1: they're they're kind of principles, are there. Yeah, they're close
Speaker 1: cousins because a lot of the thing that go into
Speaker 1: what makes flash drives work apply to solid state drives.
Speaker 1: But an excellent resource on the Web is an Ours
Speaker 1: Technica series, one of which one of the articles in
Speaker 1: that series is called Solid State Revolution in Depth on
Speaker 1: how s s d s Really work by Lee Hutchinson.
Speaker 1: And I can't say enough good things about this article.
Speaker 1: It really is a comprehensive approach to how solid state
Speaker 1: drives work. And there's a little, uh, little latitude in
Speaker 1: the article, so it makes it it's not it's not
Speaker 1: dry reading. No, well, our our Technica is like that. Um.
Speaker 1: It's also just just as a note, it's also very
Speaker 1: technical in spots too, so if you know, it's it's
Speaker 1: a they there site. It takes a little bit different
Speaker 1: approach to technology than than we do in a good way.
Speaker 1: It's at a different level. So it's it's definitely more
Speaker 1: serious if you if you're already familiar, Yeah, if you're
Speaker 1: already familiar with UM with computer art, texture and data
Speaker 1: and that sort of thing. Uh, it's an excellent resource. Otherwise,
Speaker 1: it may it may feel a little advanced for someone
Speaker 1: who is just curious about this but doesn't have any
Speaker 1: real background. However, acts well worthy. Chris and I will
Speaker 1: return in just a moment to talk more about solid
Speaker 1: state drives, but first let's take a quick break. So
Speaker 1: getting back to solid state drives. So the idea of
Speaker 1: creating a solid state drive is was really really attractive
Speaker 1: because of that decreased latency. Um, there were some challenges
Speaker 1: of course, because solid state drives they do not store
Speaker 1: information magnetically the way traditional hard drives do. Now, actually
Speaker 1: it sort of reminds me of electronic ink in a way. Interesting. Well,
Speaker 1: if you know something about electronic ink, you know that
Speaker 1: the capsules white or black generally are stored in between
Speaker 1: a sandwich of h material that holds a positive or
Speaker 1: negative charge, and that's how it reads a page. But
Speaker 1: once the page is there, it stays there. I see.
Speaker 1: So you're thinking of that as for it. Let's just say,
Speaker 1: for example, that the black parts of the screen are
Speaker 1: ones and the white parts are zeros, and they retain
Speaker 1: that even when the power is off, so they're non volatile. Right.
Speaker 1: That means that when you remove the power source from
Speaker 1: this system, it keeps that information. Of that of course
Speaker 1: is extremely important when it comes to computers because, like
Speaker 1: Chris was saying, RAM is volatile memory. If you lose
Speaker 1: that power, then that information goes away. There's no longer
Speaker 1: a charge to maintain the information that's stored in your
Speaker 1: computer's memory. You don't want that to happen to your
Speaker 1: hard drive because that means that every time you would
Speaker 1: turn off your computer or lose power, you would lose
Speaker 1: all the data stored there. You have to have non
Speaker 1: volatile memory to keep storage a possibility. Well, nice, yeah,
Speaker 1: because I mean the old, the old, old, old computers
Speaker 1: that that Chris and I worked on didn't have hard drives.
Speaker 1: You had to store things on magnetic discs. If you
Speaker 1: turned your computer on, it just went to its initial state.
Speaker 1: The only thing that was stored on there was the
Speaker 1: operating system because it was written in read only memory,
Speaker 1: which was non volatile, but it was also unchangeable. You
Speaker 1: couldn't write to it. So that meant that, you know,
Speaker 1: if you wanted to write a program, you had to
Speaker 1: store it on a disk, because if you tried to
Speaker 1: write it just on your computer, you didn't have a
Speaker 1: disk in there, and you turned the computer off, all
Speaker 1: your work has gone. This is also why if you've
Speaker 1: ever worked on a computer, and you've ever heard anyone
Speaker 1: say save your work, often that's why when you save
Speaker 1: your work, it's being saved to your hard drive not
Speaker 1: to your computer's memory. So if you're working on something
Speaker 1: and you haven't saved it in a while, it may
Speaker 1: only exist in your computer's memory. If power goes out,
Speaker 1: you may lose all that work, as I have done
Speaker 1: on multiple asians. I was actually in my college's computer
Speaker 1: lab during a storm and the screams power went out.
Speaker 1: There's nothing like working in any sort of computer environment
Speaker 1: when the power goes out and then you hear there's
Speaker 1: there's usually about a second and a half delay between
Speaker 1: the power going out and every single person making essentially
Speaker 1: the same noise which sounds like this. Ah. I leaned
Speaker 1: back as I did that, so there was a little
Speaker 1: Doppler effect. But anyway, so yeah, this this sort of
Speaker 1: of non volatile memory means that that information is going
Speaker 1: to stay there even when you turn the power off.
Speaker 1: This is the exact same sort of stuff we find
Speaker 1: in our MP three players and other mobile devices that
Speaker 1: because again, if we didn't have that, then every time
Speaker 1: you turned off your MP three player, you would lose
Speaker 1: your entire library of songs. You have to reload it
Speaker 1: the next time you turn it on. Right, right, Well,
Speaker 1: there is um to to complete my analogy along with
Speaker 1: the electronic ink thing. The flash memory also uses cells.
Speaker 1: Um it stores information in in cells, and that cell
Speaker 1: is either a one or a zero. Right to think
Speaker 1: of the cells like a sheet of grid paper. Yes,
Speaker 1: and you've got rows, and you've got columns. Right, So
Speaker 1: the rows of cells. If you took one row of cells,
Speaker 1: we would call that in in solid state drive terminology,
Speaker 1: that would be a page. So one row of the
Speaker 1: cells would be a page, and then you would have
Speaker 1: several rows of cells and several columns of cells that
Speaker 1: would form what is called a block. And this is
Speaker 1: really important because it comes down to the way information
Speaker 1: is written and erased in solid state drives. It turns
Speaker 1: out that you cannot individually change the cells within that
Speaker 1: grid paper. For example, if you if you had a
Speaker 1: sheet of grid paper in front of you, you could
Speaker 1: write a one or a zero and every single grid
Speaker 1: and if you wanted to, if you were writing in pencil,
Speaker 1: you could erase a single cell and change that one
Speaker 1: to a zero or zero to a one. You cannot
Speaker 1: do that with a solid state drive. We'll get into
Speaker 1: that in a little bit, but that's an important thing
Speaker 1: to think about from the start. Well, if you know
Speaker 1: something about hard drives. The the magnetic platter hard drives.
Speaker 1: UM when you when your computer, and that pretty much
Speaker 1: goes for all modern operating systems. Let's say you have
Speaker 1: a document and you realize that well, you worked on
Speaker 1: it three years ago, You've turned it in. You know,
Speaker 1: I don't need to save it for anything, So I'm
Speaker 1: going to delete it, and I'm gonna tell my computer delete.
Speaker 1: Well that first of all, the computer doesn't delete it
Speaker 1: deleted if you just tell it to you know, throw
Speaker 1: it in the trash can, empty the trash can or
Speaker 1: recycle bin or whatever. It's actually still there on your
Speaker 1: hard drive, but it's been marked for deletion. So basically,
Speaker 1: when uh, something else, Hey I've created a new document,
Speaker 1: and the computer goes or can I say, ah, this
Speaker 1: is marked for deletion, I'll right over that old one. Um.
Speaker 1: That's one thing to note is that it can do that.
Speaker 1: That's the way that that computers work with magnetic platter
Speaker 1: hard drives. Now it also can do something else. Let's
Speaker 1: say you have five different documents and you've deleted these
Speaker 1: five documents. Well, those gaps are different sizes, but you're
Speaker 1: storing a brand new file and it's larger than all
Speaker 1: five of those. It can fill in sections sort of
Speaker 1: like packets when you send, when you break up an
Speaker 1: email file into a bunch of packets and they go
Speaker 1: and they reassemble themselves on the other side on somebody
Speaker 1: else's computer. These different gaps can be used to store
Speaker 1: parts of this file, which the computer will then reassemble
Speaker 1: as you need it. Um. That's when you need to
Speaker 1: fragment your hard drive. You know, they have sections and
Speaker 1: they're all scattered out. You've got applications, and then they're
Speaker 1: all in different places, in different sectors, on different platters, um,
Speaker 1: And they say, okay, I going to reorganize everything. And
Speaker 1: so the computer basically uses storage empty storage to reshuffle
Speaker 1: everything and put it back into sectors where all the
Speaker 1: parts of the filer together. And that makes a computer
Speaker 1: run a little bit faster when it's accessing those files
Speaker 1: because they're on one place and they don't have to
Speaker 1: reassemble them. Now, you can't do that with uh, solid
Speaker 1: state drives. Yeah. In fact, when it gets down to
Speaker 1: erasing data off a solid state drive, it's pretty pretty complex.
Speaker 1: But before we get into that, let's talk a little
Speaker 1: bit a little a little bit more about the way
Speaker 1: information is stored within these cells. So these grids on
Speaker 1: your grid paper, Yeah, I just thought it would be
Speaker 1: interesting to compare that to a platter drive entirely. Yeah,
Speaker 1: And it is important to make the comparisons between the
Speaker 1: two because there are advantages and disadvantages to both. That
Speaker 1: whole erasing thing or overwriting. You can't overwrite in an SSD.
Speaker 1: You can't erase stuff. But it takes a lot of
Speaker 1: effort actually, um. But anyway, so in order to make
Speaker 1: the the cell have a value in it, you have
Speaker 1: to apply a voltage to that cell. Yes, I couldn't.
Speaker 1: I couldn't read that article without thinking of a C
Speaker 1: d C, the band with the Dirty deeds. That they're
Speaker 1: cheap voltage. It uses high voltage. Actually that's important, yes, yeah,
Speaker 1: in fact they're well uses both high and low voltage.
Speaker 1: There are two different ways of wiring these transistors together.
Speaker 1: That's what each of the cells actually represents. Um. There
Speaker 1: is the nor approach, which is a little simpler but
Speaker 1: less useful. Really, it's typical of flash drives, however, these
Speaker 1: smaller drives. So think of think of those those rows
Speaker 1: there and the uh, the columns as having a a
Speaker 1: a circuit line going through each one. All right, so
Speaker 1: there are rows of circuit and columns of circuits, uh, connections,
Speaker 1: really electronic connections, I should say, not just circuits, but
Speaker 1: electronic connections. So the rows would be word lines, the
Speaker 1: columns would be bitlines. So you would have this grid
Speaker 1: of word lines and bitlines. Sort of it would look
Speaker 1: kind of like a city block, like if you were
Speaker 1: looking for a city landscape if you were looking at
Speaker 1: it from the air. So you have these these streets
Speaker 1: that are criss crossing um and you would kind of
Speaker 1: tell each cell what its contents were based upon applying
Speaker 1: voltages across these lines. I'm not going to get too
Speaker 1: far into this because it really gets kind of complex
Speaker 1: and also involves a concept called quantum tunneling, which we
Speaker 1: have talked about here on tech stuff before. But it
Speaker 1: makes my brain hurt because it's Quantum Tunneling is one
Speaker 1: of those things that is crazy to me. Tunneling is
Speaker 1: this concept that and it's it's a real thing, otherwise
Speaker 1: our electronics wouldn't work. Tunneling is this concept where you
Speaker 1: have a barrier, let's say, and you've got an electron.
Speaker 1: That part of me an electron that's on one side
Speaker 1: of that barrier. With the right kind of energy, that
Speaker 1: electron can pass from one side of the barrier to
Speaker 1: the other side of the barrier as if it has
Speaker 1: tunneled through without actually physically tunneling through. And this all
Speaker 1: has to do with the potential for the electron to
Speaker 1: be in one position versus another. UH. There's sort of
Speaker 1: you can think of it as a there's a radius
Speaker 1: around an electron that represents all the different locations that
Speaker 1: electron could be in. UH. If that electrons at the
Speaker 1: proper energy state, and there is a barrier next to
Speaker 1: the electron, that radius might extend beyond the other side
Speaker 1: of that barrier. That means that there's the potential for
Speaker 1: that electron to be on the other side of that barrier,
Speaker 1: which means if there is a potential for it, sometimes
Speaker 1: the electron is on the other side of that barrier,
Speaker 1: as if the area weren't there. This drives me insane.
Speaker 1: It's like saying, if I'm if I'm running fast enough,
Speaker 1: there's a chance I'm going to be on the other
Speaker 1: side of the wall, not on this side of the wall.
Speaker 1: But every time I try that, I end up with
Speaker 1: the bloody knows I'm not quantum enough, is what it. Yeah,
Speaker 1: we'll return to this classic episode of tech stuff in
Speaker 1: just a moment after we take this break to thank
Speaker 1: our sponsor. In the nand one, the bitlines are actually
Speaker 1: kind of um daisy chained in a way from one
Speaker 1: cell down to the next, and this becomes important when
Speaker 1: you were actually reading from the memory in order to
Speaker 1: determine what bit is in each cell uh. And the
Speaker 1: way that works is that you apply a weak voltage
Speaker 1: across these lines to try and determine if a full
Speaker 1: circuit is being made, and if there, you get two
Speaker 1: different outcomes depending on if there's a one or a zero. Right.
Speaker 1: So if you get one outcome, for example, if the
Speaker 1: circuit is made, you know that the value is uh,
Speaker 1: you know what the value is inside that cell because
Speaker 1: it can only be that value. And if the circuit
Speaker 1: is not made, then you know it's the opposite value, right.
Speaker 1: And so you're you're thinking, well, if the charge goes through,
Speaker 1: it means this. If the charge doesn't go through, it
Speaker 1: means that you collect that with all of these cells,
Speaker 1: and that's what builds up data. Remember, each of these
Speaker 1: cells represents one bit, so a zero or a one,
Speaker 1: unless that's a well, I guess I should say that
Speaker 1: that would be an s l C, a single level
Speaker 1: cell which can represent either a zero or a one.
Speaker 1: You could also have a multi level cell, and in fact,
Speaker 1: most ssd s are multi level cells. Now, these can
Speaker 1: contain UH two or more bits. Usually it's two bits
Speaker 1: or three bits, which means that if it's a two
Speaker 1: bit system, there are four show values that you could
Speaker 1: find within that cell. It would either be zero, zero, zero, one,
Speaker 1: one zero, or one one. But with a multi level cell, UH,
Speaker 1: it's a little more complicated as well, because you know,
Speaker 1: like I said, you could use the weak voltage to
Speaker 1: determine whether or not the content of a single layer
Speaker 1: cell is a zero or a one. With multi level
Speaker 1: level cell, because there are four potential UH outcomes, you
Speaker 1: have to use different voltages and essentially you work from
Speaker 1: the weakest and you work your way up and as
Speaker 1: soon as that circuit is complete, then you know what
Speaker 1: the value of that cell is. Did I just Chris's
Speaker 1: brains are actually leaking out of his ears right now.
Speaker 1: I just find the whole thing revolting. Yeah, I thought
Speaker 1: you would get a charge out of it, So anyway. Yeah,
Speaker 1: it all has to do with these voltages and uh
Speaker 1: and that that's all the reading information to write to
Speaker 1: a to it is um even more complex actually. Well.
Speaker 1: One of the things to note though is that making
Speaker 1: these changes, uh the voltage changes can be dangerous um
Speaker 1: using the high voltage to to do these changes, which
Speaker 1: is one of the reasons why it is so difficult
Speaker 1: to uh to erase and rewrite on this flash memory
Speaker 1: that that's used in SMCS. That's one of the reasons.
Speaker 1: The other reason is that when you are writing information
Speaker 1: to a an SSD, you have to write it in
Speaker 1: in pages so rows. So think of think of this
Speaker 1: grid paper again. You can only write to a single
Speaker 1: row at a time, all right, when you're erasing, you
Speaker 1: have to erase these in blocks of pages. You can't
Speaker 1: erase one row, you can't erase one page. You have
Speaker 1: to erase a block of pages, which tends to be
Speaker 1: about eight rows total, which equals about five and twelve kilobytes.
Speaker 1: There's actually some extra information there too, because there are
Speaker 1: a few, uh few cells that are dedicated to things
Speaker 1: like error correction and other information. So there's technically a
Speaker 1: little more than that. But the data that you're actually
Speaker 1: writing to the s s D or erasing from the
Speaker 1: SSD is either in four or eight kilobyte pages. Again,
Speaker 1: that depends upon the format of the solid state drive.
Speaker 1: And uh, when you're racing's twenty eight pages, so five
Speaker 1: and twelve kilobites so or for the four kilobyte pages anyway,
Speaker 1: so you've got you can write in a page, you
Speaker 1: erase in a block. This is why it's really hard
Speaker 1: to You can't. This is why you cannot overwrite information
Speaker 1: because your file that you know that this has nothing
Speaker 1: to do with file size, is just the individual bits
Speaker 1: that are found within those cells. Right, So a block
Speaker 1: might contain the end of one file in the beginning
Speaker 1: of another file. So you can't erase an entire block, uh,
Speaker 1: just because you erased one particular file, because you if
Speaker 1: you did that, then you would lose the beginning of
Speaker 1: a of an unrelated file that you did not delete, right,
Speaker 1: And and it treats old files that have been marked
Speaker 1: for deletion as information that should be saved. It doesn't
Speaker 1: make there's on every drive there is a controller that
Speaker 1: provides instruction for the drive, and it doesn't know the
Speaker 1: difference between the file that I just uh quote unquote
Speaker 1: on my computer deleted and the computer marks for delete. No,
Speaker 1: it's okay to overwrite this sector of the drive versus
Speaker 1: a file that I want to keep, So it treats
Speaker 1: anything that's written in there as well. I better save
Speaker 1: this and just so that you guys can kind of
Speaker 1: envision what is going on here. So let's go back
Speaker 1: to that grid paper example. Let's say you've got a
Speaker 1: sheet of grid paper. If this were like a solid
Speaker 1: state drive, every single one of those cells, if this
Speaker 1: was a brand new sheet, nothing had been saved to
Speaker 1: the sheet. Yet, actually every single one of those cells
Speaker 1: would have a one in them. And when you were
Speaker 1: writing information, what you do is you apply a certain
Speaker 1: voltage and you would switch that one to a zero. Switch.
Speaker 1: Switching the one to a zero is not such a
Speaker 1: big deal. Switching the zero back to one is a
Speaker 1: huge deal. And here's here's why you cannot overwrite specific
Speaker 1: parts of this this page. You have to use enough
Speaker 1: voltage to switch that back to a one that if
Speaker 1: you were to try and target a single cell, that
Speaker 1: energy could overflow into neighboring cells, which would make those flip.
Speaker 1: And if you're making all of those flip. That means
Speaker 1: you've just corrupted the data, right because not all those
Speaker 1: not all of those rows need to be turned back
Speaker 1: into one's sound effective. Students going yeah, so that's so,
Speaker 1: that's why you can't target a specific cell. You have
Speaker 1: to do it in these blocks. And uh. The way,
Speaker 1: the way a solid state drive actually does this handles
Speaker 1: this because eventually you will have to have that information
Speaker 1: erased or else you'll run out of space. You'll run
Speaker 1: out of space. Just even every time you save a
Speaker 1: new version of that document, if it's a document that
Speaker 1: you're working on as opposed to like we'll use that
Speaker 1: as an example, um as a type of file you're creating.
Speaker 1: Let's say that you've created a document. Every time you
Speaker 1: save a new version of it, it's writing that information
Speaker 1: to more pages on your solid state drive. Well, if
Speaker 1: you never erased, if if it never had the opportunity
Speaker 1: to erase the information on that drive, you would run
Speaker 1: out of space eventually. Yes, So the way it tries
Speaker 1: to handle this is that eventually there's a there's got
Speaker 1: to be a connection between the operating system and the
Speaker 1: solid state drive that lets the solid state drive no
Speaker 1: this particular information that is stored within your pages is stale.
Speaker 1: This information does not really um this, this isn't pertinent anymore.
Speaker 1: You can get rid of this. What will happen is rubbish. Yeah,
Speaker 1: and there's this is called garbage collection. Actually, what happens
Speaker 1: is the solid state drive will take a block that
Speaker 1: contains the pages that have stale information, and we'll copy
Speaker 1: that entire block and save it again within the drive.
Speaker 1: So now you're saying, wait a minute, now you just uh, well,
Speaker 1: technically it only copy the stuff that is um that
Speaker 1: does not stale. So you've got a block of of pages.
Speaker 1: Some of those pages are stale, some of the pages
Speaker 1: aren't stale. The solid state drive will copy the stuff
Speaker 1: that's not stale and paste into a new block and
Speaker 1: a new series of pages. So you've just doubled all
Speaker 1: the non stale content that is on your solid state drive.
Speaker 1: And I hear you screaming, but you said this is
Speaker 1: to conserve space. How can you conserve space by copying
Speaker 1: and pasting? Here's how. After that information has been copied
Speaker 1: and pasted into the new section of the solid state drive,
Speaker 1: the old block that has both the stale and not
Speaker 1: stale information in it can be erased. You can apply
Speaker 1: that high voltage flip those zeros back to one's, and
Speaker 1: you can do it safely because you've already duplicated the
Speaker 1: non stale data into new pages. The stale data does
Speaker 1: not get duplicated, so it gets erased, which means that
Speaker 1: that block is now available to write to again. There's
Speaker 1: another downside here, which is that every single time you're
Speaker 1: writing to those cells, you're actually breaking down the system
Speaker 1: a little bit. There's only so many times you can
Speaker 1: do this and the cells will remain viable. Eventually, the
Speaker 1: cells will no longer be able to hold a charge
Speaker 1: because they've been broken down too many times with this
Speaker 1: voltage being applied to them. Um SSD vendors have gone
Speaker 1: to some effort to prevent that from being an issue,
Speaker 1: at least for a while. Um In a lot of cases,
Speaker 1: there will be uhm extra space on the drive of
Speaker 1: which you are unaware. Right. You might have a say,
Speaker 1: let's say that you get I don't know, a sixty
Speaker 1: gigabit gigabyte rather hard drive space, and there's actually sixty
Speaker 1: eight gigabytes in there. You just don't know about this
Speaker 1: other eight because they've been included to take into account
Speaker 1: this issue so that one uh, this whole garbage collection
Speaker 1: process has some space to work in and you won't
Speaker 1: end up filling up your hard drive before it can
Speaker 1: take advantage of that and to as cells die and
Speaker 1: are unusable, it can open up new pages of cells
Speaker 1: that have not been written to an x number of times.
Speaker 1: And we're talking thousands of times here. It's not like,
Speaker 1: you know, it's not like you're gonna fill up your
Speaker 1: hard drive and three days later it's gonna be useless.
Speaker 1: But well, it shouldn't be, No, it shouldn't be. But
Speaker 1: but but you know, your mileage may vary depending upon
Speaker 1: manufacturer and model, but the ideally it would take thousands
Speaker 1: and thousands and thousands of times before it would become obsolete,
Speaker 1: before it would not work anymore. And the thing is
Speaker 1: that most of us use our computers frequently enough where
Speaker 1: eventually that could happen. I mean, if you upgrade on
Speaker 1: a regular basis, you may never notice this problem. But
Speaker 1: if you don't, you might notice that your computer takes
Speaker 1: longer to pull information from the hard drive that it
Speaker 1: used to and you may notice that you are running
Speaker 1: out of hard drive space when you thought that you
Speaker 1: should really have more. Why has all that gone? And
Speaker 1: it's because those cells are no longer viable. Well. UM.
Speaker 1: To prevent this, the controller on the S s D
Speaker 1: is designed to route traffic in a way that will
Speaker 1: try to put a fairly even uh distribution, distribution of
Speaker 1: usage across the different cells on the drive uh, thus
Speaker 1: hopefully ensuring that no set of cells is worn down
Speaker 1: more than the others. They're trying to put put even
Speaker 1: wear and tear on it. Um. But the more full
Speaker 1: you get now they're one of the complaints about S
Speaker 1: s D s is that they seem to grow slower
Speaker 1: as time goes on. That's because that information, uh, those
Speaker 1: those cells are getting full of information. Those pages are
Speaker 1: filling up. And because of the way they work um
Speaker 1: and they have to write and rewrite blank pages at
Speaker 1: a time, UH, it can seem to slow down because
Speaker 1: there isn't as much space to uh for them to
Speaker 1: the controller to route the information and regroup things into
Speaker 1: pages uh fresh pages that can be written and rewritten
Speaker 1: or not rewritten, but um erased and written to UM.
Speaker 1: So UM you know that that's that's sort of a
Speaker 1: I would say an illusion. It's not really an illusion,
Speaker 1: but that's why it's not because the drive is uh
Speaker 1: crapping out generally, I mean, uh yeah, I mean the
Speaker 1: vendors for these devices generally say that they're good for
Speaker 1: you know, tens of thousands of read write cycles, so
Speaker 1: they should be good for for years. Of course, that
Speaker 1: doesn't mean you shouldn't back up your hard drive. However,
Speaker 1: it does mean that defragging like we used to do
Speaker 1: with the magnetic traditional platter drives is not a good
Speaker 1: idea because you're adding to writing and rewriting uh those
Speaker 1: cells right right, You're you're effectively you are decreasing the
Speaker 1: life span of your hard drive. And the controller really
Speaker 1: should be doing that anyway, with the garbage collection and
Speaker 1: um organization of that that work, so it should be
Speaker 1: less of an issue than it used to be. And
Speaker 1: the controller really is kind of like a very small,
Speaker 1: very specialized computer. So in a way, you have a
Speaker 1: computer within your computer because the controller is is taking
Speaker 1: this information and putting it in the most uh the
Speaker 1: the optimized format and layout. So yeah, it's uh, it's
Speaker 1: an interesting approach using this voltage difference instead of magnetism
Speaker 1: in order to store information, and it has become incredibly useful,
Speaker 1: especially for things like portable electronics. I mean, it's really
Speaker 1: decreased the size of what our electronics can be. Plus
Speaker 1: you can go running with it and not worry about
Speaker 1: crashing the platters on your hard drive. Yeah, this is
Speaker 1: why back when I remember when m P three's were
Speaker 1: MP three players were first coming out, and there was
Speaker 1: always the argument of do you get the one with
Speaker 1: the spinning hard drive or do you get the one
Speaker 1: with the flash hard drive? And the flash hard drives
Speaker 1: tended to be more expensive, but they also were the
Speaker 1: ones you could go and exercise with and not worry
Speaker 1: about them, you know, something skipping around or or or
Speaker 1: corrupting a file or crashing. Um, do you would you
Speaker 1: would you like to wrap up? Or should we mention encryption?
Speaker 1: We could mention, well, you can mention encryption because frankly,
Speaker 1: my my research did not cover that topic. UM okay,
Speaker 1: well the uh UM This is another in the series
Speaker 1: of articles UM on our technical about s s d S,
Speaker 1: also written by Lee Hutchinson UM. And it's kind of
Speaker 1: fascinating because uh in in the process of UM compression UM,
Speaker 1: they go through a d D duplication phase. So it's
Speaker 1: sort of you know, if they find two copies of
Speaker 1: the same information, it will essentially get rid of one
Speaker 1: so that it takes up less space in the hard
Speaker 1: rid That's essentially how how these things are done. And
Speaker 1: it's done in UM other types of files to UM
Speaker 1: image and sound and uh, you know those kinds of
Speaker 1: things that they find the same information, they can reduce
Speaker 1: the amount of information in that file. Well, they do
Speaker 1: that with hard drives too. But one of the interesting
Speaker 1: things that that Hutchinson mentions is now that modern operating
Speaker 1: systems are allowing you to encrypt your entire hard drive.
Speaker 1: That actually makes it tougher for s s d s
Speaker 1: because they can't de duplicate that information anymore. Because once
Speaker 1: you encrypted a file, it has its own individual signature.
Speaker 1: So even if they were the same exact document um,
Speaker 1: the computer sees it as two different encrypted documents because
Speaker 1: the encryption information is slightly different, so will no longer
Speaker 1: recognize them as the same information. So you will see
Speaker 1: them as completely different information. Taking Bulky and safe exactly,
Speaker 1: so it takes up the same file will take up
Speaker 1: twice as much space if it's been duplicated, and it
Speaker 1: will not be deleted because there's just enough difference there,
Speaker 1: so that it has essentially fooled the controller into thinking
Speaker 1: it's two files, not one that's been duplicated to two
Speaker 1: files and one now. Um. The other thing, uh, the
Speaker 1: thing to know is, you know, these the devices are
Speaker 1: coming down and cost um, they're showing up more often
Speaker 1: in uh, in laptops, books and and you know, just
Speaker 1: a few years ago, I remember that it was really
Speaker 1: unusual to find a solid state drive in a computer,
Speaker 1: and you were paying a premium for that if you
Speaker 1: wanted it. And it was kind of interesting because at
Speaker 1: the time the solid state drives, while you were paying
Speaker 1: a premium, tended to have a smaller capacity than the
Speaker 1: traditional hard drives did when they first started coming out. Well,
Speaker 1: now we've seen that slowly start to change, and that's
Speaker 1: to be expected. That's the way technology tends to work
Speaker 1: in the market. We tend to see when it first
Speaker 1: comes out, it tends to be pretty expensive and fairly limited.
Speaker 1: And as it advances and we get better at the
Speaker 1: production approach, these prices start to fall and then next
Speaker 1: thing you know, it's everywhere. Yes, so um, you know
Speaker 1: it seems like they're they're becoming more common. Um, you know,
Speaker 1: even even in run of the mill laptops. However, um,
Speaker 1: you know, the cost is still not as as inexpensive
Speaker 1: as traditional hard drives UM. And you know you do
Speaker 1: have those trade offs to be made versus the traditional
Speaker 1: So if you were getting, say you really wanted a
Speaker 1: nice workstation to use at home, you already have a laptop, UM,
Speaker 1: and you were choosing whether you wanted to spend that
Speaker 1: extra hundred dollars two hundred dollars for an SSD, you
Speaker 1: know it does you would get some uh savings in
Speaker 1: in UH cost if you went with the magnetic drive, UM,
Speaker 1: but you would trade off speed for that and the
Speaker 1: number of read write cycles. Of course, magnetic drives have
Speaker 1: their own idiosyncrasies and you may or may not lose
Speaker 1: your your hard drive, right. Yeah. No, it's not not
Speaker 1: to say that that the older hard drives are any better.
Speaker 1: They just have a different set of pros and cons. Yeah, exactly. So, yeah,
Speaker 1: it all depends on what your use case scenario is.
Speaker 1: And I mean, like, i have machines at home that
Speaker 1: of both types. So I've got machines that have a
Speaker 1: spinning hard drive, I gut machines that have solid state drives.
Speaker 1: I have an external drive. That's a solid state drive
Speaker 1: that I used for backups. Uh. You know, there's a
Speaker 1: lot of different ways of going about this, and I
Speaker 1: think that both approaches have their own advantages and disadvantages
Speaker 1: that will apply to you based upon the way you
Speaker 1: use your machines. So that's always a good thing to
Speaker 1: think about. Uh. And it may even be that to you.
Speaker 1: It doesn't really matter other than maybe the fact that
Speaker 1: you can get a solid state drive with a small
Speaker 1: reform factor than you could if it were a physical
Speaker 1: hard drive, you know, the mechanical hard drive. I should
Speaker 1: say mechanical, not physical, because they're both physical. It's not
Speaker 1: it's not a virtual hard drive. Um. So yeah, I
Speaker 1: mean that's it's all up to the way you use
Speaker 1: your machines and what you what your personal preferences are,
Speaker 1: and I guess what your budget is as well. Yeah.
Speaker 1: Um yeah, I'll never forget. I knew that solid state
Speaker 1: memory was going to be a big deal. This flash
Speaker 1: based memory sticks solid state drives slightly different, but I
Speaker 1: knew it was gonna be a big deal when we
Speaker 1: went to I guess is when I went to C E. S.
Speaker 1: It was the year after the two of us went
Speaker 1: because the year that Chris and I both went to
Speaker 1: c S, we picked up lots and lots of press
Speaker 1: kits that were either paper press kits or c D
Speaker 1: comic this space. And then the next year I started
Speaker 1: seeing companies produce their press kits on USB thumb drives.
Speaker 1: And that's when I was I thought, Okay, this is
Speaker 1: a big enough deal, because now it's cheap enough where
Speaker 1: these companies can produce thousands of these things for an exhibition.
Speaker 1: Because you've got lots and lots of people at c S,
Speaker 1: you have to produce tons and tons of these not
Speaker 1: literally tons and tons, but lots and lots of these
Speaker 1: thumb drives, uh, in order to give them out to
Speaker 1: all the people who stopped by. Of course, nowadays they
Speaker 1: don't even do that anymore. Now you get a card
Speaker 1: that has a U R L and you go to
Speaker 1: a website that has the press release, which is even
Speaker 1: better really, although it does mean that I don't end
Speaker 1: up with lots of thumb drives that I can use
Speaker 1: once I erase the VATA that's on there. You mean
Speaker 1: you haven't moved everything into the cloud. Now I'm working
Speaker 1: on it, but you know there, here's the other thing,
Speaker 1: about the cloud. I mean, that's a totally different discussions.
Speaker 1: I'm gonna I'm gonna drop this. I was about to
Speaker 1: go off on a cloud rant about how all my
Speaker 1: information is in different pockets in the cloud. That's my
Speaker 1: problem now, So let's let's that's a totally different podcast,
Speaker 1: which I'm sure we'll do. And we've talked about cloud
Speaker 1: storage in the past anyway, so we're gonna wrap this up. Guys.
Speaker 1: I do recommend you go to ours Technica and look
Speaker 1: at those articles if you are interested in solid state
Speaker 1: drives and what makes them work. And that wraps up
Speaker 1: another episode, another classic episode of tech Stuff, and hope
Speaker 1: you guys enjoyed it. I really miss having those conversations
Speaker 1: with Chris. They were always a lot of fun. If
Speaker 1: you guys have suggestions for topics that I should cover
Speaker 1: in future or episodes of tech Stuff, send me an
Speaker 1: email the addresses tech Stuff at how stuff works dot com,
Speaker 1: or drop on by our website that's tech Stuff podcast
Speaker 1: dot com. There you're going to find an archive of
Speaker 1: all of our past episodes. It's fully searchable, so you
Speaker 1: can find out if I've covered a specific topic that way,
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Speaker 1: find a link to our online store, where every purchase
Speaker 1: you make goes to help the show and we greatly
Speaker 1: appreciate it, and I'll talk to you again really soon.
Speaker 1: Text Stuff is a production of I Heart Radio's How
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