Is a hard drive an input or output device?

 When learning the basics about computers it is important to understand whether a hard drive is an input or output device. At first glance, it appears that hard drives perform a range of tasks which can make it difficult to properly distinguish whether they act as an input or output device. 

A hard drive is not an input or output device, it is a storage device. A hard drive stores all of your digital content includes videos, documents, music, applications, and the operating system you are using. Hard drives have increased in size from an average of 1 gigabyte in 1990 to between 1 and 8 terabytes. 

The way hard drives pass information back and forth from the computer’s processor makes it easy to mistake as an input and output device. 

Let’s take a closer look at how a hard drive interacts with other elements of a computer to understand why it should never be considered anything but a storage device. 

What are the elements of a computer system?

To better understand why a hard drive is a storage device and not an input or output device let’s take a look at all the elements of a computer system. 

The four main elements of a computer system are the central processing unit (CPU), the memory, input devices, and output devices. They interact with one another in various ways to provide you with a typical computer experience. You can check out how these items interact below. 

Input Devices

A computer scanner, like the Fujitsu ScanScap, is an input device. Input devices send information to the computer processor which then translates that input to data the rest of the computer can use. As you can see information flows one way from the input device into the processor.  

Output Devices

Speakers, like Redragon Speakers, are output devices that take the information provided by the processing unit and then output it in some way. Speakers output the information via audio from digital files, monitors output the user feedback in visual form. As you can see information typically flows one way from the processor to the output device. Printers are also output devices but rather than audio or visual, they output physical copies of a document.

Processing Unit

The processing unit is the brain of the computer. It is where different programs, or instructions, are executed. These instructions send various pieces of information to other parts of the computers. For instance, sending a file to your printer or opening your favorite music app. We’ve discussed in detail whether a CPU is an input or output, and provided a more in-depth breakdown of the device there.


Storage or memory, like the Seagate BarraCuda 2TB, is where all your computer’s files, features, and operating system are held. The processing unit converts everything into data that the memory unit can understand, and then it is stored there until needed later. When you play a song it is retrieved from storage before being processed and then output via the speaker.  

Is a hard drive an input or output device?

A hard drive is a storage device, not an input or output device. It is used to store all of the files and applications your computer needs to run correctly and communicate with a computer’s processing unit. The average consumer hard drive has gotten over 1000 times bigger since the 1990s, exploding from just 1 gigabyte to 1 terabyte. 

People often confuse the flow of data in and out of a hard drive as it being an input or output device. A hard drive receives data or instructions from the processing unit. It then stores that data until it is needed again. When the processing unit sends the correct instructions it then gives the processing unit the relevant data back. 

The hard drive is just one form of storage that a computer uses. It is stable and permanent, so any data remains when a computer is switched off. It holds important operating system files. The other type is RAM or random access memory. RAM stores things the computer needs quickly or in real-time, but isn’t stored when a computer is switched off.

The multiple directional flows of data to and from the processor lead to people incorrectly labeling a hard drive an input or output device. The data does move both ways, so it could in theory be classified as both an input or output device. However, in the context of a computer system, it is better to separate each device by its specific function. 

All devices have elements of input and output, think turning the volume of a speaker up, or your printer displaying error messages, however, to correctly understand how a computer works we separate these.

A hard drive’s purpose is to store data and that is why we should consider it a storage device and not an input or output.

What type of device is a hard disk?

A hard disk is a storage device that forms one of the four parts of a computer system. Every modern computer has at least one hard disk. A hard disk sends and receives information from the central processing unit (CPU) but is not an input or output device. 

It can be easy to mistake a hard disk as an input or output device because of the way data travels back and forth from the processor. The processor sends your hard disk data in a storable format, whereas the storage device sends the information which is then processed into something the output devices can use.

In the context of computer systems, it is important to differentiate devices by the tasks they perform. A hard disk stores all the images, videos, apps, and operating system files that make your computer work. Therefore it must be referred to as a storage device because this is the role it plays in a computer.

All devices have some two-way communication with the processing unit in some small way, so it’s just easier to define them by the functions they perform. If the device’s main job is to send data to the processor, it is an input device. If the device’s main job is to receive data from the process and output it, then it’s an output device. A hard drive’s main purpose is to store data it receives from the processor and then send it back when requested.


A hard drive is a storage device that forms one of the four key parts of your computer. All modern computers and phones have a hard drive of some sort and they are virtual for them to function. 

Despite a hard drive sending and receiving data, it does not make it both an input and an output device. It is first and foremost a storage device that is tasked with storing data and then retrieving the data to be used at a later point in time.