Lesson video

In progress...


There, and welcome back to computer systems. I'm Mac, your computing teacher for this unit.

And in this lesson, we're going to be talking about secondary storage.

I will describe the three types of them to you and you're going to to learn more about solid-state storage.

like usual, for this lesson you're going to need a notepad and a pen, so you can take notes, while you're learning.

And I'd like you to remove all distractions from around you.

This includes your mobile phone.

You know me, I've got my water here.

And I want you to make sure you've got some refreshment, if you need it throughout this lesson.

If you'd like to pause the video, to get all of the things that you need, I'll be here, when you get back.

In this lesson, you're going to explain the need for storage devices.

We're also going to describe, the three different types of storage devices.

And take a deeper look at how solid-state storage works.

First, we're going to kick it off by talking about why memory will not do.

Storage devices like the ones we're going to talk about in this lesson, are used to store data for longer periods of time.

You learned about memory in lesson four, but why are those devices unsuitable for long-term storage.

Before we get started with this first activity, I just want to remind you of some key terms. Volatile, means that data is lost, when the power is switched off.

And non-volatile, means data is not lost when power is switched off.

So I'd like you to pause the video here and head over to your worksheet, where you've got a table with two rows.

One for RAM, and one for ROM and some key characteristics.

I'd like you to fill out the table and then come back and we'll go through some of the answers and we'll talk about the characteristics.

If you want to pause the video here, go complete that.

I'll be here when you get back.

Welcome back.

I hope you enjoyed revisiting RAM and ROM and looking at some of those characteristics.

Let's just go through them together and see what we can learn.

So, first let's talk about RAM.

So, RAM is a volatile memory device.

We've got a tick in that column.

And it's not portable.

I can't pick up a stick of RAM and just randomly plug it into another computer.

I'd need to first unconfigure it from my computer, and then reconfigure the new computer to use that RAM.

It's not really for portable data storage.

It is however, both read and write.

It's quite fast, very fast to read from.

But it has a small capacity.

Now how about ROM? ROM is non-volatile, which means that it keeps all of its data, even when power is switched off.

It's also not portable.

The ROM typically found in a computer system is attached to the motherboard of your computer, which means that to take it off and attach it to another computer, you'd have to desolder it, from the motherboard of your computer and then resolder it to the other computer.

Not possible and definitely not designed to be used like that.

ROM is read-only.

Again, it's in the name, right? So can only be read from.

It is also very fast to read, to read from, just like RAM.

and much quicker than some of the devices we'll talk about today.

But, it's capacity is tiny, even smaller than RAM.

You can barely fit anything on there, except maybe a few instructions like the BIOS.

If we haven't looked at the characteristics of RAM, I would like you to devise an answer to the following question.

Why don't we just store all of our files and programmes in RAM? I want you to make a note of your answer on the notepad.

And I want you to use the characteristics we just discussed in your answer.

If you want to pause the video here while you do it, I'm going to to have a sip of my water and I'll see you when you get back.

Welcome back.

Hopefully, you had a good time answering that question.

Let's see, so why don't we store all of our files and programmes in RAM? Well, it's not going to be a good candidate for this because it's volatile.

So we'd have to keep it powered on, if we wanted to store that data for long periods of time.

This is not possible and if it was, it would be very expensive and probably not very environmentally friendly.

It's also not portable, which is a big part of what we want from a long-term storage device.

We want to be able to take that data from one computer to the other.

And it has a very small capacity.

So, we'd have to limit the amount of files and programmes we had on our computer at any one time.

So, why don't we use ROM then if RAM is unsuitable? I'd like you to pause the video again here and answer this question.

Remembering to use those characteristics in your answer.

Welcome back again.

So why is ROM unsuitable? Well, ROM is definitely not portable.

If anything, less portable than RAM, 'cause you'd have to desolder and then resolder it, right? It can only be read from and not written to.

Which means that we couldn't use it to store files.

It just has to be flashed.

And then that is unchangeable without going through a whole process that might damage your computer.

It also has a tiny capacity, so even less so than RAM.

We would have to choose very wisely exactly what we wanted.

And usually that would just be a few instructions.

So computers need secondary storage because they store data for longer periods of time.

They're robust and reliable.

And it is much cheaper than memory.

RAM and ROM that we discussed before are quite expensive.

Especially when you get into those larger capacities.

If you want a that's larger than say eight gigabytes, you're looking upwards of 100 pounds.

It has more capacity and is portable.

These are important characteristics of secondary storage, that are not covered by RAM and ROM.

Let's have a look at secondary storage, to see which devices we use to solve these problems. So, there are three categories of secondary storage device typically used.

By the end of lesson six, which is the lesson after this one, you're going to be able to give examples of each of these, state characteristics of each and also explain how they work.

Let's have a look at each one of them individually now, before we expand on it later.

So, solid-state storage has no moving parts.

They store data inside of electrical circuits and are typically very small.

They can have a large capacity, but tend to be more expensive, especially when you get to much, much larger capacities.

This type can also be called flash memory.

Next, we have optical.

So, optical is most commonly used to distribute media and software.

Movies and video games, for example.

This type uses lasers to read and write data on a reflective surface.

These devices are typically very small in capacity, but extremely cheap to produce.

Then finally we have magnetic storage.

This one is the oldest form of storage, and it's actually been in use since the 1920s, before computers were even around.

Data is stored in series, which means one after another as polarised dots.

These devices come in very large capacities and are generally inexpensive.

Now that you've heard a little bit about the three different types of storage device, I'd like you to have a go at categorising, some devices into one of those three categories.

On your worksheet, and also on the right hand side of the slide here, I have an array of storage devices.

Your job is to decide whether they are solid-state, magnetic or optical.

If you want to pause the video here and head over to your worksheet.

You can either drag the devices or write the names of them into the appropriate row on the table.

I'll see you when you get back.

Welcome back.

How was that? Were there any that you were unsure about? Let's have a look at the answers and I'll see if I can dispel any confusion you might've had.

So, let's start with solid-state devices.

So, which of these do we think is solid-state? Well, the first one is a solid-state drive, which it looks a bit nondescript.

But you should have been able to tell because it was very thin, doesn't have any moving parts and they use electrical circuits.

But also, USB stick is a type of solid-state storage.

Sometimes called flash memory.

Just like the biggest solid-state drives, they also use circuits to store data.

How about optical? Did you manage to spot any of those? So there were three in this list, actually.

CDs, DVDs and Blu-ray.

These are all types of optical storage, that use light to store data.

And that means the three that were left, were obviously magnetic storage.

So we have a hard drive, magnetic tape and also a cassette tape.

Now a lot of you might be too young to remember cassette tapes.

But, they were very popular in the 80s and 90s for listening to music.

Now you've seen some examples of the three types of secondary storage.

We're going to take a deep dive into one particular category.

In this lesson, we're going to be looking at solid-state storage.

Now, while we're going through this, I'd like you to make some notes about any advantages or disadvantages that we mentioned as I'm going through.

So, just to reiterate solid-state storage, uses electronic circuits to store data.

They function very similarly to RAM, but they're non-volatile.

They get their name from the material they're made out of.

A solid non-moving collection of circuits.

So, solid-state drives consists of no moving parts to read or write data, a collection of circuits that are wired together, to store binary data.

And the circuits are wired together to form a grid, like you can see on the right hand side.

This leads to a few advantages for solid-state drives.

They typically have fast read and write speeds, but still slower than RAM.

They're durable.

They can withstand being dropped.

Any of you that have a USB stick will know this.

If you drop it on the floor, very little happens.

They're silent when running.

And they require less power than other devices.

If you want to pause the video here, just to make a note of these advantages, do so, and then we'll carry on.

Let's keep going.

So, I don't want you to think that there are no downsides to solid-state storage.

And to show you that I'm going to tell you a bit of a story.

Some of you might know about Tesla electric cars.

But for those of you that don't, you should know that they are a premium brand, run by Elon Musk.

They are designed to provide an excellent driving experience, while also being environmentally friendly.

Now, they use SSDs inside the car, so that they can save data and read data extremely quickly.

But, a recent article showed that Teslas were suffering from solid-state degradation.

Solid-state drives have a limited amount of read and writes.

And when the drive inside the car dies, so does the car.

Tesla cars save a lot of logging data to their SSDs.

This is so Tesla can improve their cars.

And also for things like automatic driving.

But, all of this logging and saving to the SSDs, eventually wears them out.

So they're not perfect.

They do have a lot of advantages, but there are also some disadvantages.

Let's go through some of those disadvantages.

Typically, they're very expensive per gigabyte, especially when you compare them to other storage devices, like CDs or even hard drives.

They have a lower capacity than magnetic storage, although still larger than a lot of other forms. And they can be unreliable.

And suffer from things like SSD degradation.

You want to pause the video here again, to make a note of these.

Just make sure you know, what the advantages and disadvantages of solid-state storage are.


I hope you got all of that.

That's all from me today.

I hope you enjoyed this lesson.

And really, well done on this deep dive into secondary storage.

In lesson six, we're going to look more, at the other two types of storage.

Before you go, I'd like to ask you, to share your work with Oak National.

If you'd like to, of course, please ask your parent or carer to share your work on Instagram, Facebook or Twitter.

Tagging @OakNational and #LearnwithOak.

I'll see you next time and happy learning.