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CSEC IT: Input Devices

In this post, we will cover:

  1. Key input devices, point and draw input devices and source data automation input devices

  2. Advantages and disadvantages of each

  3. Applications of each


Key Input devices

Key input devices are those devices that use an assortment of keys or buttons with preassigned values to send those values to the computer. The user simply presses these keys to send signals into the computer.

A) Keyboard


The keyboard is one of the most commonplace and ubiquitous input devices used today. It is considered to be one of the two primary input devices (other than the mouse) used with the computer due to its essential contribution to the complete computer system. Each key on a keyboard is marked with a particular character, symbol or function. It is used to input text, commands and certain functions into the computer or another similar device.


A standard Windows keyboard will comprise 104 keys including alphanumeric characters, symbols, function keys, arrow keys, modifier keys, navigation keys and a number pad. However, laptop keyboards and thumb sized keyboards are more compact and condense the keys into a smaller form factor.

Most keyboards used in English-speaking countries are arranged in the QWERTY layout, however, many more exist, such as the DVORAK layout, QWERTZ layout, AZERTY layout and JCUKEN layout (see Appendix Fig 2-6). These are generally used in other countries with different main languages.

Keyboards are used in many different applications in different, such as in journalism, where a keyboard will be used to input the text for an article into a word processor on a computer. Keyboards are also used in ATMs, where the keyboard takes the form of a number pad with a few function keys used to enter characters and signals into the machine.

An advantage of keyboards is that a skilled typist can enter data very quickly, making it far more efficient than writing. A disadvantage, however, is that the constant use of keyboards over long periods can cause health issues like repetitive strain industry (R.S.I) or carpal tunnel syndrome.


B) Remote Control


The remote control is another key input device often found in and around people’s homes. This handheld input device allows the user to manipulate and control the computer from short distances. Like the keyboard, it comprises a set of buttons which give preassigned signals to the computer. Each button is either marked with a character (like a number) or a function (like volume up and down). When these buttons are pressed, the signal is sent usually by an IR blaster on the remote to an IR receiver on the device itself. The computer decodes this signal and is able to perform the desired function or enter the necessary character.


The applications of remote controls are very far reaching, as they are able to control embedded computers as well as desktops from a distance. For example, televisions, music systems, lighting systems, heating systems and air conditioning may all be controlled using a remote control.

The advantage of a remote control is that the computer can be manipulated by the user wirelessly using a convenient handheld device, which is particularly useful to the disabled. It allows users to control the computer easier and from a (however short) distance.

On the other hand, the remote control’s use of an IR blaster makes it so that the remote has to be within the line of sight of the receiver and also within a fairly close distance in order for the remote to work. That is, furniture, walls, and most other things blocking the line of sight between the remote and receiver would make it unusable as the signal would not be able to travel. Also, remote controls require batteries to work as they are not connected to the computer or another power source.



Point and Draw/ Manual Input Devices

According to fabulousdevices.blogspot.com, point and draw devices are those pieces of hardware that enable the user to send spatial input into the computer. That is, multi-dimensional movements of the device direct the movement of the cursor on the screen. These devices are considered more natural for use than other devices because the user manually directs a corresponding object on screen to the desired location.

A) Mouse


The mouse , the other primary input device, is considered a necessary component to the computer’s function. The computer mouse is designed to fit into the right or left hand, and can be connected by a wire or wirelessly through an RF receiver or Bluetooth. Towards the front of the mouse, there are usually two buttons, a right-click button and a left-click button. Between both buttons is a scroll wheel used to move up and down pages.

Computer mice are usually one of two types: optical and mechanical. On the underside of a mechanical mouse, there is a rubber or metal ball that is pressed firmly against a y-axis wheel and an x-axis wheel that turn based on the movements of the ball when the mouse is moved. These movements are sent to a chip that converts these analogue movements to digital signals, which are then sent to the computer through a cable.



A mechanical mouse may also come in the form of a trackball mouse , which has a ball located on the upper side of the mouse. The mouse itself is not moved around, but rather the ball on the top is rolled around using the thumb, fingers or palm in order to control the cursor on screen. There is also a scroll wheel usually located beside the central trackball.



On an optical mouse, a light is shone from a small hole in its underside. Then, a photoreceptor detects light reflected from the surface as the user moves the mouse. This light is magnified so as to detect smaller distances and shifts made by the user. The photoreceptive cell converts the light into digital signals which the computer is able to pick up.

The buttons work identically on both mechanical and optical mice. That is, they both have microswitches under the left and right mouse buttons that detect when the buttons have been pressed. According to explainthatstuff.com, some mice use potentiometers to detect movement of the scroll wheel with others use optical rotary encoders.

An application of the mouse is in computer-aided design, where the mouse would be used to navigate the program and perform certain functions like manipulating object properties.


Some advantages of the computer mouse are that it is often included in new computer systems, it effectively accompanies the mouse in data entry, and employees do not require training with them because they are usually subsequently familiar with it.


In contrast, the computer mouse requires a flat open area near the computer in order to work most efficiently, which is a disadvantage (this does not apply to trackball mice however). Mechanical mice containing a rubber ball may also lose accuracy over time due to the gradual accumulation of dirt and dust. The mouse will therefore need to be cleaned to restore its proper function.



B) Light Pen