Input and Output Devices of a Computer

input and output devices of computer


A computer comprises a number of peripherals. A peripheral, simply put, is any device that can be used to put data or information into the computer or get information out of it. Earlier, the term peripheral was used to describe a device or a component that was used externally in a computer system. These devices were called external peripherals and auxiliary components. 

Peripherals or devices attached to a computer are primarily of two types, input devices and output devices. In the last couple of years, another category called ‘storage devices’ has come to the forefront which comprises devices like flash drives and hard drives. Technically, the only components of a computer that cannot be categorized as peripherals are – CPU or the central processing unit, computer case, motherboard and power supply. 

In this article, we shall discuss the various input and output devices that form part of a computer.

What are Input Devices?

An input device is a device that can send information or data to a computer. These devices are not capable of receiving signals or data from other devices. 

Some of the most commonly used input devices are mentioned below.

1) Keyboard

A keyboard is regarded as one of the primary input devices associated with a computer. The structure of a keyboard is quite similar to that of a typewriter and just like the machine, it comprises buttons that work towards creating letters, symbols and numbers and carry out a variety of other functions. 

A standard computer keyboard consists of 101 keys including function keys, LED indicators, arrow keys and control keys. Specific names are given to the horizontal rows of character keys. When you position your hands above the keyboard, they must be placed above the ‘home row’ keys or the keys in the center row of the keyboard. The keys under the home row keys are referred to as ‘bottom row’ keys. The ones over the home row keys are known as the ‘top row’ keys. 

These days, you can find a variety of keyboards in the market to choose from. The design and construction of the keyboards are two factors that help you differentiate between different models. While some keyboards feature membrane keys, there are models that are mechanical in nature. Some keyboards are split towards the middle and there are some which roll-up quite easily. 

It is quite common to find keyboards featuring the QWERTY layout but there are a few which use the DVORAK layout. Wired keyboards continue to be extremely popular even today but there are also more modern versions that can be connected to a computer with the help of wireless communication like Bluetooth or USB.  

2) Mouse

A computer mouse can be defined as a handheld hardware component that has served as one of the primary input devices for a computer system. A mouse features a cursor in a graphical user interface and buttons, all of which contribute towards enabling the user to move the pointer across the screen and choose from the wide number of text, icons, folders and files present in the computer. 

When it comes to desktop computers or PCs, the mouse is positioned on a flat surface such as a desk or a table. To ensure that the bottom area of the mouse remains sensitive and in good condition for a long time, it would be a good idea to buy a good quality mouse pad and place the mouse over it. While using the mouse, make sure that it remains over the surface area of the mouse pad. 

A lot of people are of the opinion that a mouse is not as important as a keyboard. To prove their point, they state that most people who own a laptop don’t use a mouse. It would not be fair to compare the mouse to the keyboard. The truth is that using a mouse hugely elevates one’s experience of using a computer. It makes work happen faster and in a more convenient manner. 

This compact-sized device is capable of performing a variety of functions. One of its foremost tasks is to move the pointer across the screen. You can use the mouse to move the pointer towards a file, icon or folder and then double-click on it using the left-hand button to open it. A mouse also enables the user to select text and/or multiple folders or files at the same time. 

3) Microphone

A microphone, also referred to simply as a mic, is a hardware component that was invented by German-American inventor Emile Berliner in the year 1877. It serves as an input device for computers enabling users to send audio-based data or signals to the computer. After you record your voice or any other audio via a microphone, it goes to the computer and gets saved in the hard drive of the computer. 

A microphone is used for a large number of activities like recording audio for a film or an audio clip, voice recognition, chatting on social media websites, registering the presence of noise in a studio or a room, computer gaming and recording the sounds of musical instruments. 

It is very easy to connect a microphone to a computer and using it. The rear end of desktop computers features a sound card or a microphone port wherein you can plug in a microphone. Some computers also feature a microphone port inthe front. 

In the last several decades, the microphone has evolved greatly as an audio instrument and is available in different forms today. Some of the most commonly used microphones today have been listed below. 

Omnidirectional microphone

This microphone has the capability to pick up or receive the sound coming in from all four directions. These kinds of microphones are largely utilized in professional studios for recording multiple voices or a number of instruments being played together. They are very powerful and one must be mindful about making any noise while using them. 

Unidirectional microphone

A unidirectional microphone is a type of microphone that can only pick up or receive sound coming in from one direction. A microphone of this nature proves to be useful when the user wishes to record just one person or an object. People who do podcasts or want to record only their voice while at home could benefit by using this microphone. 

Bidirectional microphone

As the name of this microphone suggests, it is capable of picking up sound waves from the front and rear end of the microphone. Bidirectional microphones are a good investment for journalists who conduct a lot of interviews. During an interview, this microphone will pick up the voices of the interviewer and the interviewee equally well. 

Close-talk microphone

A close-talk microphone is made while keeping in mind that the person using it will keep it very close to his/her mouth and then, speak.  It eliminates the possibility of external noise being recorded while an individual is speaking. Close-talk microphones are usually paired with a headset or phone and work very well when you are using voice-recognition software. 

Clip-on microphone

A clip-on microphone, also referred to as a lavalier microphone, is a wireless mic that one can operate without using one’s hands. What makes it even more convenient is the fact that the user can just clip it to his/her dress and use it.  

4) Webcam

A webcam is a camera that you can connect to your computer. A standard webcam comprises an image sensor and a lens. Some models also feature a pair of microphones for picking up sound. It is a relatively modern input device, which was invented in the early ‘90s and became popular several years later. 

The image sensors in a webcam could either be CCD or CMOS. Moderately priced webcams usually feature a CMOS sensor. Most commercial webcams are equipped to produce VGA-resolution video at 30 fps. Newer models are capable of producing video content in multi-megapixel resolutions. The kind of lens used in webcams varies from model to model. 

The webcam can capture still images or videos and send them to the computer, which then get stored in the hard drive. However, it must be remembered that unlike a digital camcorder or a digital camera, it does not feature a built-in storage system. The hard drive of the computer acts as its storage system.

The captured images or videos are made viral on the internet with the help of software. In the initial days, webcams were sold as standalone devices. While you can still buy webcams separately, a lot of laptops feature a webcam as a built-in component. On PCs, they can be connected with the help of a FireWire or a USB port.

5) Graphics Tablet

Never heard of a graphics tablet? Well, you must have heard of this device but by some of the other names it is also referred to. A graphics tablet is also known as a pen tablet or a drawing tablet. It is an input device that conveys information generated on a handheld stylus to the computer. The user uses the stylus just as he would hold and use a pencil, pen or paintbrush. Unlike a pen, there is no ink on the stylus. You just need to press the tip – neither too hard nor too soft – on the surface of the tablet screen. 

If you don’t own a mouse, a stylus can be a good device to have around. If you already have a mouse, then investing in a stylus will make your work a little faster and easier. The development of the first graphics tablet can be traced back to the early ‘80s. The KoalaPad was the first ever graphics tablet that was designed to be used for domestic or home computers. Though originally made for the Apple II computer in the year 1984, it was soon made available for computers that were compatible with IBM PC. 

Imagine an artist sketching or drawing something out on a white sheet of paper. The process of drawing or writing something on the graphics tablet with the help of a stylus is similar. The drawing strokes made by the user get converted into digital form and are displayed on the computer screen. 

This device is also used to capture or record signatures made by the human hand. It is quite similar to signing a bill after you have purchased something using your credit card. Graphics tablets are used by a large number of professionals including architects, engineers, illustrators, artistes, cartoonists, fashion designers, photographers, graphic designers and teachers. 

6) Trackball

Ever thought about how would a mouse look like if it was turned upside down? It would look exactly like a trackball. A trackball carries out almost the same functions that a mouse does. You can move the pointer on the screen with the help of a trackball by simply using your finger or thumb. While the mouse continues to be the more popular device among the two, many prefer the trackball as it requires lesser physical effort.

A trackball requires you to move your wrist and armless frequently than a mouse does. For this reason, the user feels quite relaxed while using a trackball instead of a mouse. Medical experts have stated that using the trackball reduces the chances of an individual suffering from RSI or repetitive strain injury. 

A trackball is the brainchild of Ralph Benjamin who invented it in the year 1946. It was given the name ‘roller ball’ upon its invention and was designed in a way that it could be used along with a military radar plotting system. For the longest time, trackball was a military secret. These days, cordless trackballs have become very popular. 

7) Scanner

A scanner, also known as an optical scanner, is an input device that scans an image, transforms it into a digital signal and sends it to the computer. A scanner can be utilized to convert a drawing, a printed picture or a hard copy of a document into a digital file, which can be then viewed and edited on a computer.

A scanner is categorized as an input device because it is like an evolved form of a digitizer, which was always looked upon as an input device. A digitizer’s job is to scan a real-world object like a picture or a document and convert it into digital signals for the computer. Unlike a printer, a scanner cannot receive information from the system. 

One can use a variety of interfaces to connect a scanner to a computer but these days, a USB cable is predominantly used for this purpose. There are also specialized scanners available in the market. For example, a card scanner serves the purpose of scanning business cards and a sheetfed scanner specializes at scanning paper by inputting information about it into the scanner. 

What are Output Devices?

A device that is capable of receiving data or information from a computer and processing it is called an output device. After receiving the data or information, the output device projects, displays or reproduces it in a physical format. 

Some of the most commonly used output devices are mentioned below.

1) Monitor

A monitor, simply put, is the screen on which you see the visuals while using a computer. It is used only for the purpose of displaying information or output from a computer and does not provide the user with any source of input. This is the reason why a computer monitor is categorized as an output device. While a computer is not dependent on a monitor to function, the user would not be able to interact with the user interface of a computer in the absence of a monitor. Without a monitor, you will not be able to figure out what is executed by a computer at any point of time. 

Ideally, monitors can be two different types. The CRT or the cathode-ray monitor is the oldest version of the computer monitor that resembles the bulky TV sets used back in the day. The second type has two variations based on their backlighting, LED and CCFL. Computer monitors are required to have at least one monitor connector to be able to connect to a computer. Some of the modern video ports that help in connecting a monitor to a computer are USB-C, HDMI, Thunderbolt, DisplayPort, VGA and DVI. 

2) Printer

A printer is a hardware that works as an output device for the computer. Its primary function is to process the electronic data or information saved in the computer and produce a hard copy out of it. For instance, if you write down the details of a project in an MS Word file and need a hard copy of the same to share with your colleague, a printer will be required for the job. 

Printers have always been one of the sought-after output peripherals for a computer and can be found in most offices where they are used to take printouts of text-based documents or pictures. A wide variety of printers are available in the market today. While laser and inkjet printers continue to be the most popular ones, some other prominent ones are the 3D printer, thermal printer, dot matrix partner, AIO/all-in-one printer and MFP/multifunction printer and plotter. 

Every specialized printer serves a different function. While a 3D printer is used to print parts or tools that are required to build something, a laser printer is utilized to take bulk printouts of text-based documents. An inkjet printer is most suitable to print documents that are required to be signed later manually. That’s the reason why you need to be sure about your purpose of getting a printer when you decide to invest in one.  

There are different ways in which you can get your printer connected to your computer. The most common method of connecting it to a computer is through a USB cable. However, if you prefer wireless connections, you can connect them through Wi-Fi. Some other interfaces through which you can get it connected to a computer system are through a serial port, Firewire, Cat 5, MPP-1150 and SCSI. 

3) Speaker

A speaker is a hardware device that can be connected to a computer to produce sounds. These sounds are produced with the help of signals that are generated by the sound card of the computer. Most modern-day speakers are made with constituents like an iron coil, a cone, a powerful magnet and a housing/case. 

The initial computers featured onboard speakers that were built into their frames. These speakers produced a variety of tones and even some strange sounds. IBM invented the first internal computer speaker in the year 1981. This particular device was known to generate sound that is strictly functional. As time passed, better quality speakers came into the market. 

What also prompted companies to manufacture speakers that offered better sound was the fact that different avenues like cinema, music and gaming were growing rapidly. As sound gained prominence, consumers became more and more willing to invest in good quality speakers. A lot of people started looking for speakers that were capable of producing a wide range of sound effects.

Speakers are rated in terms of watts, total harmonic distortion and frequency response. The amplification capacities of a speaker are measured in terms of watts. The term frequency response refers to the rate at which highs and lows of the sound waves produced by a speaker are measured. THD or total harmonic distortion is the extent of distortion that takes place when you amplify the signal. 

4) Headphones

Headphones perform the function of transferring audio signals from a computer to the receiver. The task performed by a pair of headphones is almost the same as that of a speaker. However, unlike speaker, headphones provide you with a private aural experience. 

When you are with a group of friends and everybody is interested in listening to music, you can play a track on the speakers but if you want to listen to a piece of music or watch a film on your own without disturbing the people around you, a pair of headphones is what you need. American inventor Nathaniel Baldwin devised the first pair of headphones in the early 1900s and since then, the device has been introduced in different shapes and sizes by different companies. 

While a lot of people imagine headphones to be large, these days you get them in small and compact forms. Earbuds, for instance, are tiny wireless devices that fit in your ears comfortably and can get connected to an accompanying device via Bluetooth. Most companies provide consumers with rubber inserts of different sizes in the same box the ear buds come in. 

5) Projector

A projector reads the images produced by a computer or a device like a Blu-Ray player and projects them onto a screen. If you don’t have a screen at your disposal, you can also project the images reproduced by the device on a wall or some other surface that you find suitable. Make sure the surface or material you choose is flat, large enough to accommodate the projection and lightly colored. 

An inventor called David Hansen secured a patent for the first-ever carousel slide projector on May 11, 1965. However, the digital projector that is widely used today is the brainchild of Gene Dolgoff. While he stumbled upon the idea for creating such a device in 1968, his dream was finally realized in 1984 in the form of a machine.  

Projectors are capable of reproducing both still images and videos on the screen. This device is lightweight and weighs just about a couple of pounds. A lot of people find the projector to be a limiting device but the fact is that it serves a variety of functions and proves to be useful on multiple occasions. 

A projector is used in offices to project or display a presentation in front of a large group of people. Many people use it in their homes to catch up on a film with their family members. A corporate executive can utilize a projector in a convention center to give a demonstration of a newly launched product by his company. These days, a lot of people also use it to change the appearance of a particular space in the house. They use the projector to play a video or project certain images on the wall to make the room appear livelier and more vibrant.

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