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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


The light pen is a specialized device with a sensitive tip that enables users to directly interact with the computer using their monitor. This pen can only be used with CRT (Cathode Ray Tube) Displays, as the electron rays emitted by the monitor are used to ascertain the position of the pen on the screen and also the objects on screen.


The light pen was used more in time periods before 2000 when CRTs were more widespread, but its application was usually in graphic design. The light pen allowed artists to draw on screen with greater spatial positional accuracy than a mouse. It was also used in Computer-Aided Design by architects, mechanical drafters and other professions.

The advantages of a light pen include:

1) It is a selection tool with high precision compared to other devices like the mouse, which is fairly awkward to draw smooth lines with. A light pen allows the user to control exactly where on screen they would like to draw or ‘click.’

2) The light pen requires little space on the desk as only it and a CRT monitor are required.

The disadvantages of a light pen include:

1) A light pen, to be used effectively, forces the hand to be in a sort of awkward position, even if the monitor is tilted. This can result in wrist strain.

2) The light pen can only be used with a specialized type of monitor designed to interact with it. These monitors are usually built using Cathode Ray Tube technology, which makes them very heavy and difficult to move around.

3) Light pen systems are a very niche specialized tool, meaning that it would be difficult to procure one today, much less a CRT monitor to use it with.

4) This device requires software written specifically for it, making it a much more time-consuming and costlier task for it to be implemented in a workplace or business environment.


C) Joystick


The joystick is a point and draw input device that is used by moving the upward standing stick mounted upon the base in different directions to control the computer. The movement of the centrepiece is across 2-axes (2 dimensions). Therefore, the angle and direction of the joystick is converted from analog movements into digital signals by the base and sent over a wire (usually connected via USB) to the computer. The base of the joystick tends to have a few buttons on it which can be mapped to perform certain functions on the computer.


Joysticks are generally used in several applications, such as gaming, where the movement of the joystick may be used to control a character in game or other in game elements. Another example is in airplanes, where the pilot moves the joystick to send signals to an on-board computer in the cockpit in order to control the airplane’s pitch and roll. Joysticks are also used in mobility scooters/motorized wheelchairs so that the user can send instructions to an embedded computer that controls the motors in order to move forward, turn, etc.


The advantages of this device include:

1) They provide a more realistic and immersive gaming experience, especially in flight simulation games.

2) They allow for fast reactions by pilots and are also useful for remotely controlling unmanned vehicles.


The disadvantages of the joystick are as follows:

1) Some users consider the joystick more difficult to use than a traditional mouse. This is because a joystick cannot effectively select items on screen like a mouse can.

2) Joysticks are also a bit more fragile than many other devices and can break when too much force is being applied to them.


D) Touch Terminals


Touch screen terminals are input devices which enable the user to directly interact with the computer without additional equipment like a mouse or keyboard. The user is able to use his or her finger to touch the screen of the device and select whatever element is on screen in the corresponding area (no stylus required).


Touch screen terminals are usually one of three types: resistive, capacitive and surface acoustic wave. All may be interacted with using the human finger.

Resistive touchscreen devices are able to detect user input based on pressure applied to the screen. This technology consists of several layers within the screen, so that when pressure is applied, the outer layer is pushed onto the lower layer, causing the device to register input corresponding to the location of pressure.

Capacitive touchscreen devices detect user input by sensing the conductivity of the object being placed on the screen. This is usually the skin on the human fingertip, which is conductive, unlike other objects like styluses and gloves. This detection method increases its responsiveness compared to resistive touchscreen displays.

Surface Acoustic Wave touchscreen devices send sound waves over the surface of the screen using transmitters to receivers on the other side of the screen. The system is able to detect when a touch has occurred when the amplitude of the sound wave has fallen.

The most widespread application of touch terminals is in mobile phones, where touch screens (usually, but not limited to the capacitive variety), are placed on the front of the phone to allow convenient and quick interaction with the phone in a small form factor (without the need for a physical keyboard or mouse). Touch terminals are also used in modern electronic cash registers, so that the cashier no longer needs to enter commands on a keyboard or select them by mouse, and can simply tap with their fingers to select the requisite function.


The advantages of touch terminals include the following:

1) It is far faster than using a keyboard or mouse. Selecting something by tapping it with your finger is way quicker than moving the cursor to it using the mouse. This speed becomes a major factor for businessmen to consider, as this additional efficiency could be invaluable when taking orders or otherwise.

2) Much more desk space is made available when a touch terminal/touch screen is used. The touch screen eliminates the need for space consuming hardware like the mouse or keyboard, and therefore increases the amount of free space on the desk.

3) The touch screen is also a very simple way to control the computer and is more natural, as reaching out and touching the desired element is far more familiar than navigating to it with a mouse. This makes it a good choice for novice users and requires little training, if any.


The disadvantages of the touch terminal are as follows:

1) In order to use the touch terminal, the user must be close to the screen. This reduces the freedom of the user and forces them to sit closer to the computer than if they were using a keyboard and mouse, which allow you as must distance as there is in the range (for wireless devices) or as much distance as there is in wire (for wired).

2) The touch terminal is also prone to becoming very dirty. The display can accumulate dirt, grease and dust from being handled by sweaty fingers or simply being left for dust build-up.

3) This device is also a lot less accurate than a mouse, because trying to tap small objects on screen is far more difficult than navigating to them more precisely using a mouse.



E) Pads and Tablets


Graphics pads or tablets are made up of a flat pad which the user draws on with a specialized pen. This allows the user to input drawings directly into the computer. The pen is radio controlled in most devices instead of touch controlled, and also contains a pressure sensitive tip that can change different variables in programs on the computer based on programs. Usually, drawing lighter results in lighter lies being drawn and pressing harder results in heavier/thicker lines being drawn. As the user draws on the tablet, the image is created on screen in the program.

The applications of pads and tablets include in graphic design where it provides the user with the ability to produce more accurate drawings in programs like Adobe Illustrator or Corel Draw. A capable graphical artist can use a graphics tablet to create incredible illustrations. Interior designers and fashion designers also use this device to demonstrate their ideas in a digital form.


The advantages of pads and tablets include:

1) It is a more familiar and natural way to draw diagrams and art than with a mouse, as it recreates the set-up of drawing with a pen and paper.

2) The graphics pad/tablet allows a greater level accuracy in drawing. Each pixel on the screen is mapped to a specific area on the graphics pad, allowing the user’s movements using the pen to be accurately represented on screen.


The disadvantages of pads and tablets include:

1) The graphics tablet is not as effective for general selection work, like pointing and clicking on menus as it is for drawing.

2) These devices are usually far more expensive than computer mice.

3) The specialized pen, though usually wireless, still needs to be recharged after enough use.