Storage devices require both a physical interface and a communication protocol to exchange data with a computer. Common examples include SATA, PCIe, NVMe, and USB, each with distinct connectors and signaling standards.
Storage Device Interfaces & Protocols
We store our data on these storage devices, but somehow we need to get that data from these devices to our computer. How do we do that? We do it by connecting to it. We have to have an interface that connects between this device and our computer. Not only that, but we have communication that needs to flow back and forth between this device and the computer, and that computer is going to need to know how to talk to this device. So that's where our interfaces, how we connect to it, and our protocols, how we communicate to it, come into play.
We have both protocols and interfaces. We can think of interfaces as the way it connects to the computer, or connects to the machine. We can think of the protocols as the signaling that happens across there.
We can think of this like the difference between a plug and the electricity that goes across that plug. This plug right here plugs into a device, and there's certain ways that this is shaped and formed and how it comes together, so that is the interface between these two. And then there's electricity that passes across that.
It's the same thing with your storage devices. It needs to plug into your motherboard or your computer, and then it needs to transfer data across that connection.
What I have right here is a storage device and a motherboard, and what we're going to do is connect it using this SATA cable right here. I'm going to plug it into one of these ports right here, and I've got five different SATA ports right here and I can plug it into there. So this is the interface that's going between this and this drive right here. I'll plug this into the drive, and now they're physically connected together.
But now what they're going to do is they need to know how to speak to one another, and so there's a protocol, that's the SATA protocol, that communicates back and forth so that this device right here, this motherboard, this computer, can speak to this storage device, which happens to be a hard disk drive.
We also see something similar when it comes to memory. We can see that the memory has these different slots, and I can pop this into a — well, this is the interface that goes between the motherboard and the RAM, and so there is the RAM that we have installed right there.
There are other interfaces on this motherboard. For instance, this is a PCI slot. We also have USB, so I can plug in some storage devices via USB. So there's other ways that we can actually utilize — oh, trying to put it in the wrong spot — there's different ways that we can plug in or interface between the devices and this motherboard here.
Typically the interface lines up with whatever protocol is being used. For instance, this is a SATA cable right here, and I can plug it into this drive, which is a 3 1/2 inch form factor hard disk drive, and I can plug it into this interface right here on the drive. Now what's going to communicate across here is going to be a SATA protocol, or a SATA communication with the board.
Same thing, this is a 2 1/2 inch, so I can plug that in as well. Now this is actually mSATA, so the protocol is still SATA, that communicates to the board with SATA, but I can't plug this into it. This has a different interface to it. So the interface still determines that SATA is the protocol that it's going to communicate across, but not all SATA connections, not all SATA interfaces, are exactly the same.
Same thing, I can show you an example here. This is a PCI communication that happens, so this PCIe. If you notice, this is the same type of signaling, the same protocol, that's used for communicating between the motherboard and this device that's communicating back and forth. These are PCI slots, but you'll notice that they don't really fit into any one of these slots, so this is really a different interface here that's going to connect to your device. This is called NVMe, but what we do is we're going to connect it, and the protocol that's going to be used to communicate is called PCIe.
Just one more example here is USB. This is USB, universal serial bus, and so we're probably pretty used to using USB on our computers, and this just gives us access to a flash drive so that way we can take our files with us.
Here's another example right here of a SATA port. This SATA port right here is an external SATA, so the interface is a little different. So if I tried to plug in my SATA cable into there, that would not work in this external SATA. The interface is a little different here.
Again, there's a lot of different protocols and interfaces. A lot of times we see that they line up between the interface and protocol, but there is some variance that we see there. Another thing that often lines up is sometimes the form factors. For instance, we've got mSATA right here, which, as the name suggests, uses SATA as a protocol, and that's the interface into your motherboard.
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