1. Which usually loses its contents without power?
- RAM
- ROM
- SSD
Check the answer and reasoning
RAM
Ordinary RAM is volatile; persistent storage is designed to retain data.
CS / IGCSE
Hardware, architecture and embedded systems
A processor fetches, decodes and executes instructions using registers and buses. Clock rate, cache and core count affect performance, but no single specification determines every task’s speed.
Learning objectives
- Explain hardware, architecture and embedded systems using a concrete example.
- Apply the worked method and justify each step.
- Recognise the limitation described in the final check.
The big idea
A processor fetches, decodes and executes instructions using registers and buses. Clock rate, cache and core count affect performance, but no single specification determines every task’s speed.
Primary memory, secondary storage, input/output devices and embedded systems have distinct roles. A sensor measures a property; an actuator changes a physical process through an output signal.
Worked example
Which register holds the address of the next instruction in a simple fetch cycle?
Follow the solution
The program counter identifies the next instruction address before the fetch sequence updates it.
Investigate and explain
Predict the worked result before calculating. Change one input, record the new result, and explain which assumptions still hold.
Use the prediction activity below; a local model appears only where it supports this topic.
Check your understanding
2. Which register holds the address of the next instruction in a simple fetch cycle?
- Accumulator always
- Program counter
- Memory data register always
Check the answer and reasoning
Program counter
The program counter identifies the next instruction address before the fetch sequence updates it.
3. Is a sensor itself necessarily an actuator?
- Yes
- Only if digital
- No
Check the answer and reasoning
No
A sensor supplies measurements, whereas an actuator performs a physical output action.