Lesson Notes By Weeks and Term v4 - JHS 2
COMPONENTS OF COMPUTERS AND COMPUTER SYSTEMS
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COMPONENTS OF COMPUTERS AND COMPUTER SYSTEMS
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
Subject: Computing
Class: JHS 2
Term: 1st Term
Week: 4
Grade code: B8.1.1.1.3
Strand code: 1
Sub-strand code: 1
Content standard code: B8.1.1.1
Indicator code: B8.1.1.1.3
Theme: INTRODUCTION TO COMPUTING
Subtheme: COMPONENTS OF COMPUTERS AND COMPUTER SYSTEMS
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Good day, learners. We have learned that output devices show us the results of the computer's work. One of the most important output devices is the printer, which gives us a physical copy (hard copy) of our digital work. We see printed things everywhere in Ghana – from the receipt we get at Melcom to our end-of-term reports and the posters for community events. Today, we are going beyond the common printers we know. We will explore several special types of printers, including one that helps visually impaired people to read, and another that can build objects from scratch!
First, let's remember what a printer is. A printer is an output device that takes text and graphics from a computer and transfers the information to paper or another physical medium.
Today we are examining six specific types of printers. a) Braille Printer (Embosser) What it is: A special printer that produces documents for people who are blind or visually impaired. Instead of ink, it creates raised dots on heavy paper. These dots form the Braille alphabet, which can be read by touch. How it works: It uses pins (called solenoids) to press or "emboss" dots upwards into a sheet of thick paper. The computer sends the text, and the printer's software translates it into the Braille dot patterns before printing. Key Features: Prints raised dots, not ink. Uses special, thick paper. Can be noisy when embossing. Crucial for accessibility and inclusive education. Ghanaian Context: The Akropong School for the Blind uses Braille printers to produce textbooks and examination papers for their students, allowing them to learn and write exams just like any other student in Ghana. b) Impact Printer (e.g., Dot-Matrix Printer) What it is: An older type of printer that works by physically striking an ink-soaked ribbon against the paper. It's like a typewriter for a computer. How it works: A print head with a matrix of tiny pins moves across the paper. The computer instructs which pins to strike the ink ribbon at any moment, creating a pattern of dots that form letters and images. They are well-known for their distinct, loud printing sound. Key Features: Uses an ink ribbon. Very noisy during operation. Low cost per page. Excellent for printing on multi-part forms (carbon copy paper) because the physical impact can go through several layers. Ghanaian Context: Many banks in Ghana still use dot-matrix printers to print customer account statements. Also, businesses like the Electricity Company of Ghana (ECG) or Ghana Water Company have used them to print bills on multi-part paper. c) Inkjet Printer What it is: The most common type of printer found in homes, schools, and small offices in Ghana. It creates high-quality images and text. How it works: It sprays microscopic droplets of ink from cartridges onto the paper. The print head moves back and forth, precisely placing dots of different colours (Cyan, Magenta, Yellow, and Black - CMYK) to form the final image. Key Features: Uses liquid ink in cartridges. Quiet operation. Excellent for printing in colour, especially photos. The printer itself is often cheap, but the ink cartridges can be expensive to replace. Ghanaian Context: The internet cafe or communication centre in your town uses an inkjet printer to print your assignments, CVs, and letters. Your school's administrative office likely uses one to print letters and reports. d) Thermal Printer What it is: A printer that uses heat to create an image on paper. It does not use ink or toner. How it works: It uses a print head that generates heat. This heat is applied to special heat-sensitive paper (thermal paper), which turns black where it is heated. Key Features: No ink, ribbons, or toner needed. Very quiet and very fast. The special thermal paper can be expensive. The printout can fade over time, especially if exposed to heat or sunlight. Ghanaian Context: When you buy items from Shoprite, Melcom, or any large supermarket, the receipt you get is printed by a thermal printer. MTN Momo agents and bus conductors who issue electronic tickets (like at the VIP bus terminal) also use portable thermal printers. e) Wax Printer (Solid Ink Printer) What it is: A printer that uses solid sticks of wax-like ink. How it works: It melts the solid ink sticks and then sprays the molten ink onto the paper, where it cools and solidifies instantly. Key Features: Produces vibrant, rich colours. Prints are slightly raised and have a waxy feel. Good for a wide range of paper types. Less common and mainly used for professional graphic design work. Ghanaian Context: A professional graphic design company in Accra that creates high-quality flyers, brochures, and posters for businesses might use a solid ink printer to produce colour proofs for clients before doing a large print run. f) 3D Printer What it is: A revolutionary printer that builds physical three-dimensional objects from a digital design file. How it works: Instead of putting ink on paper, it builds an object layer by layer. The most common method is Fused Deposition Modeling (FDM), where a plastic filament is heated and squeezed out through a nozzle, tracing the shape of each layer. The layers fuse together to create the final solid object. Key Features: Creates physical objects, not documents. Uses materials like plastic filament (PLA, ABS), resin, or even metal powder. Can create complex and custom shapes that are impossible to make with traditional methods. Ghanaian Context: The College of Engineering at KNUST in Kumasi uses 3D printers to help students create prototypes for their projects. A Ghanaian entrepreneur could use a 3D printer to make custom phone cases, jewelry, or even spare parts for machines that are hard to find in the market.
Guided Practice (With Solutions)
Instructions: As a class, let's work through these questions together.