IGCSE · Practice questions · Instruction sets and embedded systems

Built in, dedicated.

Six original Cambridge-style questions on instruction sets and embedded systems, with mark-scheme style solutions.

Original questions All questions on this page are original work, written in the Cambridge IGCSE style. They are not from past papers. They test the same concepts and skills the syllabus rewards.

Keep these straight

Dedicated or general.

Instruction set: all the machine code commands a CPU can process.
Instruction: opcode (what to do) and operand (data or address).
Embedded: dedicated function, built into a device, small, cheap, low power, fixed program.
General purpose: PC or laptop, many functions, user installs software.

Recall

[2 marks]

State what is meant by an instruction set and give the form its commands are in.

A list of all the commands that can be processed by a CPU. ✓
The commands are machine code (binary). ✓

Explain

[2 marks]

An instruction is made of an opcode and an operand. Describe each part.

Opcode: the operation to be carried out (for example ADD or LOAD). ✓
Operand: the data, or the address of the data, the operation uses. ✓

Recall

[2 marks]

Describe what is meant by an embedded system.

A computer system (microprocessor) built into a larger device. ✓
That performs a dedicated function. ✓

Recall

[3 marks]

Identify three devices that commonly contain an embedded system.

Any three, e.g. washing machine / microwave / fridge. ✓
Car (engine management, ABS, airbags) / security system. ✓
Lighting system / vending machine / traffic lights. ✓

Explain

[3 marks]

Explain three differences between an embedded system and a general purpose computer such as a laptop.

Embedded performs one dedicated function; a laptop performs many different functions. ✓
Embedded usually has a fixed program in ROM; a laptop user can install and run different software. ✓
Embedded is usually smaller, cheaper and uses less power than a laptop. ✓

Apply

[2 marks]

A smart thermostat controls the heating in a house. Explain why it is an example of an embedded system.

It is a microprocessor built into the heating system/device. ✓
It performs one dedicated function: reading the temperature and switching the heating on or off. ✓

Mark this once you have attempted all six and checked your working. It records a Practiced badge on the topic and adds a one-time bonus. Revealing the solutions alone does not count.