When using computers, we can customize our experience by connecting different peripheral devices. Input devices are essential because they enable us to "send commands" to the computer, allowing us to perform simple tasks like typing a document, navigating a webpage, or recording a voice note.
Glossary
Mouse | A pointing device that processes 2-D movements on a surface. |
Trackball | A pointing device that processes rotation on a ball. |
Trackpad | A pointing device that processes touch on a small surface. |
Keyboard | Writing device that has keys for different symbols. |
Light Pen | A pointing and writing device that is shaped like a pen. |
Gamepad | Sending commands by pressing buttons. |
Joystick | Digitizes rotation movements that emulate a gear stick. |
Webcam | Device that records footage. |
Microphone | Device that captures sound. |
What is a Peripheral Device?
A peripheral device is a piece of hardware that is used to transfer information either into (input) or out (output) of a computer. The term peripheral refers to all input and output devices that are attached to a computer and are controlled by the computer system, but they are not interally a part of the computer system. This means that if two people buy the same computer, each person can select different peripheral devices in order to customise the overall experience.
The Everday Desktop
Let us have a first look at something we can all relate to. Here is a typical home scenario, utilizing multiple input and output devices.
Input Devices The mouse, keyboard and microphone take movement, typing and audio respectively, and convert them to signals for the computer to interpret.
Output Devices The VDU (monitor) and speakers give feedback to the user through visual images and sounds.
For now, we will take a closer look at various input devices. We categorised these by how people use them.
Pointing Devices 👉
With any 2-D Graphical User Interface (GUI), pointing is a key action to be able to take. Clicking, dragging, resizing are all derived from the ability to point a cursor. Here are some devices we use for pointing:
A mouse is a staple hardware device, and comes with many variants. Some have more buttons than others, and gaming mice also provide more comfortable ergonomics.
A trackball is also useful for precision work. The ball allows the user to make tiny movements, such as for work on architecture drawings or schematic designs.
Most laptops come with a trackpad, that saves the need for a mouse. This is useful for on the go situations, but can get difficult to do things like drag and drop.
Writing Input Devices ✍️
Often we need put text information into a computer. This may be numbers, letters, sentences and paragraphs. For writing, our go-to piece of hardware is the keyboard.
Keyboards have different layouts, referenced by the first 6 letters of the first row of letters. Most English speaking countries use QWERTY keyboards. You'll also see it includes a mix of:
Letter keys
Number keys
Special keys e.g., function keys, arrows, Caps Lock etc.
Light Pen with a touchscreen Allows the user to write with the assistance of handwriting recognition software. While not as accurate as typing, it can be useful for small screens. The accuracy often depends on the neatness of typing, and how well the program "learns" the style of the writer.
Voice Recognition This might feel like cheating, but at times, it is simply easier to speak what we would like written. We can use this software with a microphone. One can think of scenarios where your hands are not available like driving or cooking, or perhaps the user has visual impairment or limited hand mobility.
Movement Input Devices 🙋♀️
Sometimes we need to tell the computer about some complex movement. Gaming is the most typical example. Even though we can play games with the combination of a keyboard and mouse, sometimes movement is easier with fewer keys and using one device instead of two.
Gamepads are the standard in all gaming consoles, and can also be hooked up to a desktop PC. They work well with most games, providing the ability to move in 3D space, select options on menus, and even type using arrows and keys.
A joystick can be used in certain scenarios where the movement is even more complex, such as a flight simulator.
Motion controllers are a new addition, using a camera sensor to track natural movement, such as playing virtual tennis. They are the easiest to learn, but require more hardware (a camera) and are not suitable for all scenarios.
Talking Devices 🗨️
Some input devices allow us to communicate better by streaming video and audio to software applications that create realistic communication experiences for example: videoconferencing and multiplayer gaming.
A webcam allows others to see you and comes standard with most laptops. This is an input device. Standalone webcams can also be used with security applications as surveillance devices. The resolution of webcams makes a big difference to their use. Low-resolution cameras can make videoconferencing a let down 🙍🏽♂️.
A professional microphone streams audio to applications such as Skype, Zoom or games that have in-game voice chat. Microphones are input devices. They are also usually built into laptops, but professional microphones provide much better quality.
So many devices... how do you standardize?
There are so many peripheral devices to choose from and so many manufacturers that make them. This is possible because computer systems come with standard ports. A port is a connection, found at the front or back of a computer, that permits a computer to connect to a peripheral device. Multiple monitors or mice are expected to hook into the computer in the same way so that the transfer of data is standardised.
There are two kinds of ports:
Serial
The bits to be transmitted are sent one after the other on the same line, e.g., USB. We normally use serial transmission for peripheral devices that need to transfer a small amount of data at a relatively slow rate like an external microphone, mouse or keyboard. We have seen examples of such devices in this post already. ✅ Serial data transfers are less prone to errors, even over long distances.
❌ Serial data transfers are slower because it needs to be encoded and decoded.
Parallel
The bits are sent on different lines at the same time, e.g., HDMI. We normally use parallel transmission for peripheral devices that need to transfer a high amount of data quickly like a monitor, or a printer which are not an input devices, but an output devices. We will see examples of such devices in the next post. ✅ Parallel data transfers are simpler and significantly faster than serial.
❌ Parallel data transfers are prone to synchronization errors.
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