The CPU & Microprocessors (Cambridge International IGCSE Computer Science)
The CPU
Spec point — "1 (a) Understand the role of the central processing unit (CPU) in a computer (b) Understand what is meant by a microprocessor"
The CPU & Microprocessors
What is the purpose of the CPU?
- The purpose of the Central Processing Unit (CPU) is to fetch, decode and execute instructions
Exam Hint To earn marks, don’t just say “the CPU processes data.” You need to use keywords like fetch, decode, and execute—these match the language in the mark scheme.
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The CPU is the brain of the computer and its job is to take an input, process data and produce an output
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It is central to all devices including:
- Laptops
- Desktops
- Games-Consoles
- Mobile Devices
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Data and commands are inputted by the user using an input device, the central processing unit (CPU) processes data by executing instructions and the results are outputted to an output device
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Below is an example of data being inputted, processed and the results being outputted
| Step | Example |
|---|---|
| Input | A keyboard is used to input a number |
| Process | If the instruction being executed is ADD, the inputted value is added to an existing value |
| Output | The result of the calculation is outputted to the user via the monitor |
A diagram showing the input, process, output sequence followed by computer systems
Microprocessors
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A microprocessor is a type of integrated circuit that is contained on a single chip
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It contains the CPU and sometimes other components such as:
- Memory controllers
- I/O interfaces
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It is a hardware chip that houses the CPU
Exam Hint Examiners sometimes test the difference between a CPU and a microprocessor. The CPU is a component. The microprocessor is the chip that may include the CPU and other parts like memory and I/O controllers.
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