Computer Hardware: Internal Device – JSS3 Digital Technologies Lesson Note (Second Term)

Internal hardware devices are the physical parts inside the system unit that process, store and power a computer.

Behavioural objectives

1. State the function of the motherboard, the CPU, RAM, the hard drive and the power supply unit.
2. Explain the difference between RAM and a hard drive.
3. Differentiate between an HDD and an SSD.
4. Explain why a computer needs a power supply unit.
5. Describe the order in which internal parts work together when a game is opened.

What are internal hardware devices?

Internal hardware devices are the components fixed inside the computer case (system unit).

• Motherboard: the main circuit board that connects all parts.
• CPU: the chip that processes instructions.
• RAM: the short-term working memory.
• Hard drive: the long-term storage (HDD or SSD).
• Power supply unit (PSU): the box that supplies electricity to every part.

What is the motherboard?

The motherboard is the large circuit board, often green or blue, that holds and connects all the other parts of the computer.

• Role: it works like the “central nervous system” and lets the parts send data to one another.
• Plug-in parts: the CPU, RAM and hard drive all connect to it.
• Rule: a component that is not connected to the motherboard cannot work.
• Pathways: thin lines on the board carry data between parts, like highways.

What is the CPU?

The CPU (Central Processing Unit) is the small square chip on the motherboard that processes instructions, so it is called the “brain” of the computer.

• Input handling: every mouse click or key press is processed by the CPU.
• Control unit: directs the flow of instructions and data.
• Arithmetic Logic Unit (ALU): does calculations and comparisons.
• Speed: measured in gigahertz (GHz). A higher figure usually means faster processing.

Why does the CPU have a fan?

• Heat: the CPU works hard and becomes very hot.
• Cooling: a fan, usually with a metal heat sink, sits on top of it to remove the heat.

What is the difference between RAM and a hard drive?

RAM holds data the computer is using now, while a hard drive keeps data for long-term storage.

What is RAM?

RAM (Random Access Memory) is the computer’s short-term memory.

• Desk analogy: RAM is like the top of your school desk. Your book and calculator are placed there so you can reach them quickly.
• More RAM: you can keep more apps open at the same time without slowing the computer.
• Temporary: everything in RAM is wiped when the computer is switched off.

What is a hard drive?

A hard drive is the computer’s long-term storage, where files are kept even when the power is off.

• Locker analogy: it is like a school locker or bookshelf where books are kept safe until tomorrow.
• Stored items: photos, games, documents and the Windows operating system.
• HDD (Hard Disk Drive): stores data on spinning magnetic disks. It is cheaper but slower and has moving parts.
• SSD (Solid State Drive): stores data on flash memory chips. It is faster and has no moving parts, but costs more.

How do RAM and a hard drive compare?

What is the power supply unit (PSU)?

The power supply unit is the metal box in the system unit that changes mains electricity into the low-voltage power the computer needs.

• Why it is needed: electricity from the wall socket is too strong for the delicate chips inside.
• Its job: it converts AC (alternating current) from the socket into low-voltage DC (direct current).
• Distribution: coloured wires carry power to the motherboard, the hard drive and other parts.
• Heart analogy: as the heart pumps blood round the body, the PSU supplies electricity to every part.

What other internal devices are found in a computer?

Some computers also contain extra cards and devices that add features.

• Graphics card: produces the pictures and video shown on the screen.
• Sound card: produces the sound sent to speakers or headphones.
• Network card: connects the computer to a network or the internet.
• ROM (Read-Only Memory): keeps start-up instructions even when the power is off.

How do the internal parts work together when you open a game?

The parts work in sequence, and each one has a clear job.

1. Hard drive: the game is stored here while the computer is off.
2. CPU: you double-click the game icon and the CPU processes the command to start it.
3. RAM: the game files are copied from the slower hard drive into the faster RAM, so the game runs smoothly.
4. Motherboard: the instructions and data travel back and forth along its pathways.
5. Power supply: it keeps electricity flowing so the computer does not shut down.

Teacher’s activity

• Show real parts: bring an old, broken system unit to class if one is available.
• Handle: let students see a RAM stick, the CPU fan and the power supply.
• Identify: ask students to name each part and state its job.

Evaluation

1. Which part is called the “brain” of the computer?
2. Which part is like a desk, and what happens to its contents when the computer is switched off?
3. State the job of the power supply unit.
4. Which part connects all the other parts together?
5. Give two differences between an HDD and an SSD.

Assignment

Draw a table with the headings Part, Function and Analogy. Fill in the rows for the motherboard, CPU, RAM, hard drive and power supply unit.