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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, 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, 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.

F) Stylus

A stylus is a pen-shaped device made of a conductive material with a piece of rubber at the tip. This type of stylus (with a rubber tip) is usually used with capacitive touchscreen devices to allow the user greater accuracy in selection of objects on screen. Some styluses have a hard tip, usually to be used with resistive touchscreens as these do not work based on the conductivity of the object being placed on the screen. Styluses are usually used with smartphones and tablets to provide greater precision than the human finger.

The applications of styluses are seen in digital art, where a graphical artist will use a stylus with a touchscreen in order to draw more naturally on a screen. Styluses are also used with touchscreen devices in notetaking, drawing in art apps and also for navigations.

The advantages of styluses are as follows:

1) Styluses don’t leave smudges on the screen like a finger would, nor would it leave fingerprints. This would reduce the frequency at which a display would have to be cleaned.

2) Some styluses have a fine touch point, allowing the user to achieve greater accuracy for small touch points/small on-screen elements like the keys on the keyboard.

The disadvantages of styluses include:

1) Styluses aren’t usually very robust, and so can break if they are used with too much force.

2) Styluses, even when they have buttons on them, are not perfect replacements for computer mice. Some iterations without buttons would not be able to quickly do things like right-click and scrolling.

Source Data Automation/Direct Data Entry Devices

According to knowlesys, source data automation is “the process of collecting data at their point of origin in digital form.” From this, it can be inferred that source data automation devices are input devices that input data from their origin point in a digital form. Data is read directly from a source and is sent to the computer. These devices are the opposite of manual input devices, which require physical interaction with the device for input.

A) Optical Mark Reader

Optical Mark Readers are devices which read the marks of pens or pencils on predefined positions on a paper. It is similar in form to a printer; it has a rear area for page feeding and a front area for sending the pages out after they have been read. These devices record the presence or absence of a mark in a certain area and even the location within that certain area. Its detections are sent as input to the computer and may be stored as a file. Many lines may be read at the same time. The mark reader is able to tell which options have been marked by reflecting light off of the page. Less light is reflected by areas which are marked. These small differences in light are detected by the optical mark reader.

The optical mark reader is used in automated test marking and also automated questionnaire result tallying. Multiple choice question responses are marked by ascertaining which letter heading the mark was made under. The marks given are stored in a file which is compared with the correct answers in order to procure the student’s grade.

The advantageous qualities of an Optical Mark Reader (OMR) include:

1) OMRs input data very quickly. That is, with a certain machine, 10,000 forms can be read per hour.

2) OMRs provide consistent accuracy when reading data, surpassing the accuracy of even key-entry clerks because it eliminates the possibility transcription errors.

3) Only one computer is needed to collect and process the data input from the OMR.

The disadvantages of OMRs are as follows:

1) Incorrectly filled out forms can result in reading errors and the inability to recognize what was marked.

2) If marks made don’t fill the space completely, or the mark is not made in a dark enough pencil, they may not be read correctly.

3) OMRs can only read one out of a selection of answers, and are therefore unsuitable for text input.

4) The answer sheet placed into the device must be identical to all others being read. A blank sheet cannot be used to mark the answers.

B) Optical Character reader/Magnetic Ink Character Reader

An optical character reader system comprises a scanner with character recognition software. The scanner scans the image with the characters on it and sends it to the computer, where the character recognition software analyses the scanned characters and concerts it into a form that may be edited by a normal word processor.

Optical Character Readers (OCRs) are found mostly in post offices to quickly recognize post codes on the letters in offices.

The advantages and disadvantages of Optical Character Recognition include the following:


  1. It is much faster and cheaper than having someone manually enter large amounts of text.

  2. Recent software has been upgraded to recognize and recreate tables and original layout of scanned writing/text.


  1. Have only 95% accuracy, so text scanned by OCRs need to be checked because some letters can easily be misread.

  2. The condition of the original document also plays a large role in the OCR’s accuracy, as a lower quality document with less legible handwriting will cause more mistakes to be made in reading.

  3. Less efficient than manual typing for small amounts of text.

Magnetic Ink Character Readers are devices that specifically read characters printed in magnetic ink/toner (usually containing iron oxide). A magnetic reader head in the MICR system has the characters pass over it. The head magnetizes the ink, and each character produces a unique magnetic waveform that is detected by the device. The magnetic information is then converted into characters.

MICRs are mostly used in banks for the automatic processing and clearing of cheques. An MICR line is found at the bottom corner of cheques. This number is used to recognize and validate it. Counterfeit cheques will be denied, because they would not have the magnetic ink printed on them (magnetic ink printers are very expensive).


  1. Very accurate, more accurate than OCR. It has an error rate of less than 1%.

  2. Using MICR, the magnetic ink is still readable by the reader even if the document is obscured by ink or similar things. The iron oxide ink allows readability, even with marks over it.

  3. MICR is very secure the characters must abide by a specific format and font and use precise iron oxide ink. This makes the documents difficult to forge.


  1. The equipment for MICRs is very expensive. The readers themselves are pricey, and the printers also only use special cartridges of magnetic ink that can cost up to 250 USD per unit.

  2. MICRs are only able to recognize a few characters when they are in a specific font and format.

C) Webcam

The shortened form of ‘web camera,’ a webcam is simply a compact, small digital camera connected to the computer which allows the user to take pictures, record videos and even video chat using programs like Skype. Most webcams are connected to the computer via USB, but recent iterations have become wirelessly connected. Webcams are made up of a small camera mounted on a base that clips on to the top of the computer monitor and gives it the ability to pan and tilt. Some have an integrated microphone and even a light that turns on when the webcam is on.

The most commonplace application of webcams is in video chatting. Programs like Skype and Discord allow a live feed of video and audio to be sent over the internet between two people in order to communicate. Another application is in video creation, where people record themselves to upload to YouTube or just for personal use. The same is true for picture taking, where a person may take a picture of themselves for personal use, for example as a profile picture online.

Advantages of the Webcam

  1. Webcams are very cheap due to their low-quality materials.

  2. Webcams are very convenient for quick video creation and also for video chatting. Being able to see the face of the person you are talking to over the internet is a great advantage gained from using webcams, as people across long distances can talk ‘face-to-face.’

Disadvantages of the Webcam

  1. Webcams have very low video quality when compared to professional video equipment. When video chatting, the feed from a webcam may seem pixelated and low-quality.

  2. Due to the presence of hackers on the internet, webcams can be activated by these people who illegally gain access to the computer. This causes a great breach in people’s privacy.

D) Barcode Reader

The barcode reader is a direct data entry input device that scans a code known as a barcode, decodes it and sends it to the computer.

A barcode is a series of black bars with varied widths that correspond to values that give information about the item it is placed on. The barcode reader works by shining a light beam across the barcode and measuring the light reflected. The dark spaces in the barcode reflect less light than the white spaces, allowing the reader to differentiate between them. The light is converted to data (usually a series of letters or numbers) by the decoder and sent to the computer. The computer, of course, is able to make sense of the string, which may be assigned to a certain item in the inventory of a store


There are five types of barcode readers: image scanners, slot scanners, Charge-Couple Device (CCD) scanners, pen wands, and laser scanners.

An image scanner, or camera reader, works by taking a picture of the code using a small camera, then decoding the barcode using image processing. Its range is between 3 and 9 inches. It is also cheaper than a laser scanner.

A slot scanner is a stationary barcode reader, where the barcode is pulled by hand through the scanner.

A Charge Couple Device (CCD) Scanner, used mostly in retail sales, is in the shape of a gun and has to be held less than 1 inch from the barcode in order for it to be read. It converts each pixel that it sees into an electrical charge that varies based on the colour that it sees, and sends this to the computer.

Pen wands are the least expensive and least complex type of barcode reader. The pen wand must be placed right on top of the barcode and slid over the entire barcode at a specific speed.

Laser scanners have the highest range and do not need to be near the barcode to read it. A system of mirrors and lenses are used in it, allowing the scanner to read the barcode unaffected by orientation. A laser scanner can easily read a bar code up to 24 inches away. To increase accuracy, a laser scanning may perform up to 500 scans per second. Laser scanners may be handheld (shaped like a gun) or stationary (in one place).

The most well-known application of the barcode reader is in supermarkets, where they (usually laser scanners) are used to scan items which customers want to purchase. The barcode on an item will be scanned, decoded, and sent to the computer, where the product code’s assigned price will be displayed and added to the bill.

Barcode readers are also used in ID card checking, where usually a slot scanner will read the barcode on the back of the ID card, validating it.

Advantages of Barcode Readers

  1. Barcode Readers capture data quickly and accurately, cutting down on a lot of paperwork and reducing errors that may occur in manual transcription. This helps in inventory checking, where product codes can be recorded quickly and with less errors than doing it by hand.

  2. The use of barcode readers also reduces labour cost and time used, as hours that would have been used doing paperwork are now reduced to simply pointing and scanning barcodes.

Disadvantages of Barcode Readers

  1. In order to use barcode readers, everything that is needed to be scanned must already have a barcode on it. So, applying these barcodes, especially in large inventory warehouses, can become very expensive and time-consuming.

  2. Barcode readers other than laser scanners (which are quite expensive with accompanying software) need to be held within a certain proximity for the scanner to read the barcode.

E) Scanner

The scanner is a device that uses light to convert items printed on paper to a digital format that can be used by the computer. There are four main types of scanners: flatbed scanners (the most common and versatile), sheet-fed scanners, handheld scanners and drum scanners.

Flatbed scanners work by having a beam of light move across the surface of what is being scanned. The light is reflected onto light sensitive diodes known as Charged Coupled Devices that convert photons into electrons or electric charges, differing based on the colour reflected.

Sheet-fed scanners are similar to flatbed scanners, but the document being scanned is moved while the scanner stays stationary.

Handheld scanners are basically the same as flatbed scanners, but the light beam has to be moved manually by the user. Its image quality is far lower than that of a flatbed scanner.

Drum scanners are specialised scanners used by the publishing industry for the capture of high-quality images using technology known as Photomultiplier Tube (PMT). In this technology, the item to be scanned is placed on a glass cylinder. At its centre, the glass cylinder has a sensor that divides light coming from the document into three beams. Each beam is sent through a colour filter into a PMT to convert photons into electrical signals.

Scanners are of course used in the publishing industry, where newspapers and other documents are scanned for digital archiving. Scanners are also beneficial to the general consumer as they are able to scan images and important documents to use them in digital documents, send them to others and archive them safely.

Advantages of Scanners

  1. Scanners can accurately recreate images and produce high quality digital results.

  2. Scanners can reproduce a document without causing any harm to the original piece.

  3. Once scanned, images and snippets of text can be included in documents.

Disadvantages of Scanners

  1. Scanners are quite slow as devices for digitizing documents. It can take about 20 seconds to scan one page, but this time grows exponentially with additional volumes.

  2. Scanner maintenance, especially for large scanners that deal with large quantities of paper, can be very expensive.

  3. Scanners, to operate at peak efficiency, need regular servicing and arts replacements due to constant usage.

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