JSS 1 First Term

Learning Objectives

• Identify input and output devices found in a computer system.
• State the function of each common device.
• Classify devices that act as both input and output.
• Choose the correct device for a given task.

Input Devices

An input device sends data and instructions into the computer. The keyboard is the main text device. The mouse is the main pointing device. The scanner reads a printed page. The microphone captures sound. A touchscreen receives commands by touch. A webcam captures a live picture.

A joystick or game pad is used in games and in training simulators. A barcode reader is used in shops to read product codes. A digital camera captures still pictures. Biometric devices such as a fingerprint reader and a face scanner are used to control entry to a building or a phone.

Output Devices

An output device presents the result. The monitor shows text, pictures and video and is the most used output device. A printer produces a paper copy. A speaker produces sound. A projector enlarges the screen for a class. A plotter draws large diagrams such as building plans.

A hard copy is a printed output that lasts. A soft copy is an output shown on screen and disappears when the screen is cleared.

Devices That Do Both Jobs

Some devices act as input and output at the same time. A touchscreen shows information and receives touch commands. A multifunction printer prints, scans and copies. A headset both plays sound and records it. Learners should classify such a device by the job being done at that moment.

Choosing the Right Device

Choosing a device depends on the task. To enter text, use a keyboard. To select a menu item, use a mouse or a touchscreen. To send a photograph, use a webcam or a scanner. To produce a permanent copy, use a printer. To record a lesson, use a microphone.

More Input Devices in Detail

A scanner converts printed pages into digital files. A flatbed scanner takes a page on glass, a handheld scanner is moved over the page, and an all in one printer can scan, print and copy in one machine.

Pointing devices move the cursor on the screen. The mouse may be optical, laser or wireless, and a laptop uses a touchpad or a trackball. A barcode reader reads the black and white lines on a product and is used in shops, libraries and hospitals. A joystick controls games and machines, and a light pen points directly at the screen.

Display Devices and Printers

A display device shows information on a screen. Older CRT monitors are heavy and thick, while modern flat screens use LCD, LED or OLED technology. Resolution is the number of pixels, the tiny dots that make up the picture, so a higher resolution gives a sharper image.

A printer puts the result on paper as hard copy. An inkjet printer sprays tiny drops of ink and suits colour photos and small jobs. A laser printer uses toner powder and a laser beam and is fast and sharp for offices. A thermal printer uses heat and is used for shop and bank receipts.

Practical Work

1. Walk round the laboratory and record ten different devices with their category.
2. Use a scanner to scan a page and print the scanned copy.
3. Record five seconds of sound with a microphone and play it back.
4. Classify ten written device names as input, output or both, and explain each choice in one line.

Scenario-Based Questions

1. A school buys a device that prints, scans and copies. Explain why this counts as both an input and an output device.
2. A student is asked to type a two page essay. Name the best device and explain why a scanner would not suit the task.
3. Explain why a barcode reader in a supermarket reduces the time spent at the payment point.
4. Name three output devices and give one use for each.
5. A learner wants to read a printed textbook page on a computer. Name the input device needed and explain its use.
6. Explain the difference between a hard copy and a soft copy with one example of each.
7. A touchscreen computer replaced separate keyboards and mice in a bank. Give two advantages and one disadvantage.