← IGCSE Computer Science Paper 1

Disadvantage: faults, power cuts and hacking

When an automated system stops working or is harmed, for example by a faulty sensor, a power cut or hacking, so the whole process may fail. A backup or manual control helps.

Part of: IGCSE Computer Science 0478 — 6.1 Automated Systems — Module 41

Understanding Disadvantage: faults, power cuts and hacking in IGCSE Computer Science Paper 1

What it does: The code switches to a battery when the mains fails, so the process keeps running instead of failing. When a fault is found, a person takes control, so the process does not stop completely. The microprocessor trusts the sensor data. A faulty sensor gives wrong readings, so the system makes wrong decisions. Sensors, microprocessors and actuators all need power. Without it the whole process can stop. Connected systems can be attacked by hackers. This is a cyber security risk and is not a sensor fault. A backup or manual control lets the process carry on or be made safe if the automated system fails.

Common mistakes: A reading of -999 means the sensor is giving a wrong value. The fault flag must be set to TRUE so the system knows the sensor is faulty. When the main power is cut, the system should switch to the backup battery. Switching the battery off means no power at all, so the system fails.

Class: _____________________ · Name: _____________________ · Date: _________

Free printable worksheet with full answer key — or add this module to a class and your students practise it interactively.

🖨 Print worksheet + answer key Add Disadvantage: faults, power cuts and hacking to a class →

This module's key terms are also in a printable crossword (Modules 608–617) and word search (Modules 608–631).

Take this worksheet further — free with Cloodit

Each concept is reinforced from every angle — learned, then applied, then tested.

Learning

Duo

A temperature sensor in a greenhouse is faulty and always reads 10°C. What is the most likely result?

The microprocessor repairs the sensor by itselfThe heater may stay on and overheat the plants

Matches

A hacker cannot harm a system that is connected to a network

↓

Connected systems can be hacked. A cyber attack can change settings or stop the system, so security is needed.

Applying

Meanings

Term

system failure

Meaning

When an automated system stops working or is harmed, for example by a faulty sensor, a power cut or hacking, so the whole process may fail. A backup or manual control helps.

Practice

reading ← READ_SENSOR()

Testing

Gaps

sensorValue < 0 THEN

Check Answer

Spots

2IF temp = -999 THEN

3 fault ← FALSE

Cloodit turns curriculum-aligned coding content into journeys students work through one biome at a time.

Students earn collectable badges

Over 100 of them, across seven natural biomes.

Study Buddy

Students build a real study resource

Turns their work into revision material ready for Flash Cards and Exam study.

Diamond Dash — one of Cloodit's live, competitive Sprint games

Students lock in with Sprints

Live, competitive practice for the start of the lesson or a teacher-led lesson finisher.

A Cloodit certificate of achievement, ready to personalise and print

Custom printable certificates

Honour your top performers, or encourage a student who's trying hard — ready to print in seconds.

Add to class →

Quick Questions

1. A temperature sensor in a greenhouse is faulty and always reads 10°C. What is the most likely result?

A. The microprocessor repairs the sensor by itself

B. The heater may stay on and overheat the plants ✓

The microprocessor trusts the sensor data. A faulty sensor gives wrong readings, so the system makes wrong decisions.

2. Which statement about power cuts and automated systems is correct?

A. No power means the system cannot work ✓

B. Automated systems keep working without power

Sensors, microprocessors and actuators all need power. Without it the whole process can stop.

3. Which is a risk of connecting an automated system to a network such as the internet?

A. Hackers could take control of it or stop it ✓

B. The sensors will always give wrong readings

Connected systems can be attacked by hackers. This is a cyber security risk and is not a sensor fault.

4. Which is the best way to reduce harm when an automated system fails?

A. Have a backup system or manual control ✓

B. Remove all human workers from the site

A backup or manual control lets the process carry on or be made safe if the automated system fails.

5. A power cut stops an automated factory line. Which type of problem is this?

A. A hacking attack on the microprocessor

B. A power failure that stops the whole process ✓

A power cut is a loss of electricity supply. It is not caused by a person attacking the system.

Match the Pairs

IF sensor_reading = 999 THEN → A faulty sensor is sending a wrong reading, so the system may react incorrectly

IF mains_power = OFF THEN → A power cut has happened, so the system may stop working unless there is a backup

A backup power supply keeps the automated system working during a power cut → IF mains_power = OFF THEN USE battery_backup ENDIF

Manual control lets a person take over when the automated system fails → IF system_fault = TRUE THEN SWITCH TO manual_control ENDIF

A hacker cannot harm a system that is connected to a network → Connected systems can be hacked. A cyber attack can change settings or stop the system, so security is needed.

A faulty sensor is not a problem because the microprocessor always knows the right reading → The microprocessor only sees what the sensor sends. A faulty sensor gives wrong data, so wrong decisions are made.

Key Term

system failure

When an automated system stops working or is harmed, for example by a faulty sensor, a power cut or hacking, so the whole process may fail. A backup or manual control helps.

Fill in the Blanks

1. IF sensorValue < 0 THEN OUTPUT "Sensor fault" ENDIF

Hint: Type the keyword that starts a selection, used to check for a faulty sensor reading.

2. IF mainPower = FALSE THEN backupOn ← TRUE ENDIF

Hint: Type the comparison operator that tests whether the power is equal to FALSE after a power cut.

3. IF attempts > 3 THEN OUTPUT "Possible hacking" ENDIF

Hint: Type the operator meaning greater than, to spot too many failed login attempts.

4. IF autoFailed = TRUE THEN mode ← "MANUAL" ENDIF

Hint: Type the keyword that closes the selection block when switching to manual control.

5. IF temp < -50 OR temp > 150 THEN OUTPUT "Faulty sensor" ENDIF

Hint: Type the logical operator so that either impossible reading triggers the fault message.

Spot the Error

Question 1

A temp ← READ_SENSOR()

B IF temp = -999 THEN

C fault ← FALSE

D ENDIF

Line C — A reading of -999 means the sensor is giving a wrong value. The fault flag must be set to TRUE so the system knows the sensor is faulty.

Question 2

A IF mainPower = OFF THEN

B alarm ← TRUE

C SWITCH OFF backupBattery

D ENDIF

Line C — When the main power is cut, the system should switch to the backup battery. Switching the battery off means no power at all, so the system fails.

Question 3

A attempts ← 0

B WHILE attempts > 3

C INPUT password

D attempts ← attempts + 1

E ENDWHILE

Line B — The loop should run while attempts is LESS than 3. With > 3 it never runs, so the password check that limits hacking attempts is skipped.

Question 4

A IF autoFailed = TRUE THEN

B DISABLE autoControl

C ENABLE manualControl

D MUTE alarm

E ENDIF

Line D — If the automatic system fails, staff must be warned. The alarm should be sounded, not muted, so people can use manual control.

Question 5

A IF sensorOK = TRUE THEN

B USE lastGoodValue

C LOG fault

D ENDIF

Line A — The backup action is for a faulty sensor, so the test should be sensorOK = FALSE. With TRUE it would ignore the sensor even when it works.

Student with a class code? Join your class →