IGCSE ICT: The Systems Life Cycle — Revision Notes

The systems life cycle is the sequence of stages used to replace or build an ICT system: analysis, design, development and testing, implementation, documentation and evaluation. Cambridge IGCSE ICT 0417 (Topic 7, Paper 1 Theory) expects you to describe each stage, compare the methods used within it and apply them to a scenario such as a shop, school or hospital.

Condensed for revision. For the full explanation, use the systems life cycle study guide, then test yourself with the systems life cycle practice questions.

Syllabus coverage

Syllabus ref	Content	Covered below
7.1 Analysis	Research methods; inputs, outputs, processing and problems of the current system; user and information requirements; system specification (hardware and software)	Research methods table; analysis checklist
7.2 Design	File/data structures, input formats, output formats, validation routines	Design checklist; validation table
7.3 Development and testing	Need to test; test designs, strategies and plans; normal, abnormal and extreme data; live data	Test data worked example
7.4 Implementation	Direct changeover, parallel running, pilot running, phased implementation	Changeover comparison table
7.5 Documentation	Technical and user documentation and their components	Documentation table
7.6 Evaluation	Efficiency, ease of use, appropriateness; compare with requirements; limitations, improvements, user responses	Evaluation checklist

Key definitions

Term	Meaning
Requirements	What the users and the organisation need the new system to do
System specification	The hardware and software chosen, and justified, for the new system
Validation	An automatic check that data entered is reasonable and follows the rules (not that it is correct)
Test plan	A list of tests with the test data, expected outcome, actual outcome and any remedial action
Normal data	Valid data the system should accept
Abnormal data	Invalid data the system should reject
Extreme data	Valid data at the very edge of the accepted range, which should be accepted
Live data	Real data, with known results, used to test the system
Technical documentation	Documents for the people who maintain or upgrade the system
User documentation	Documents for the people who use the system

7.1 What happens at the analysis stage?

The analyst researches the current system, records how it works and decides what the new one must do.

Method	Advantage	Disadvantage
Observation	Sees what really happens; reliable first-hand information	People may work differently when watched; slow
Interviews	Can ask follow-up questions; detailed answers	Time-consuming; interviewee may not be honest face to face
Questionnaires	Many people at once; anonymous, so answers may be more honest; quick to analyse	Questions cannot be explained; low return rate; answers may be rushed
Examining existing documents	Shows the data actually used, the forms and reports	Documents may be out of date or hard to understand

Analysis checklist (from the syllabus): identify the inputs, outputs and processing of the current system; identify problems with it; set the user and information requirements for the new system; then identify and justify hardware and software (the system specification).

7.2 What is designed?

• File/data structures: field name, data type, field length, and coding of data (for example M for male, F for female).
• Input formats: data capture forms (paper or on-screen).
• Output formats: screen layouts and report layouts.
• Validation routines:

Check	What it checks	Example
Range check	Value lies between limits	Mark from 0 to 100
Character check	Only allowed characters are present	A name contains no digits
Length check	Number of characters is correct or within limits	Phone number has 11 digits
Type check	Data is the right type	Age is a number, not text
Format check	Data follows a pattern	Date entered as DD/MM/YYYY
Presence check	Field has not been left empty	Surname must be entered
Check digit	Extra digit calculated from the others detects errors	Final digit of an ISBN or barcode

7.3 How is a system tested?

The system must be tested before implementation so faults are found when they are cheap to fix. Test designs cover data structures, file structures, input formats, output formats and validation routines. Test strategies test each module, each function and then the whole system.

Worked example: test data for a range check

Rule: a shoe size field accepts whole numbers from 3 to 12.

Type	Data	Expected outcome
Normal	7	Accepted
Extreme	3	Accepted
Extreme	12	Accepted
Abnormal	2	Rejected with an error message
Abnormal	13	Rejected
Abnormal	seven	Rejected (wrong type)

After testing with this data the system can be run with live data and its results compared with the known results from the old system. If an actual outcome differs from the expected outcome, the test plan records the remedial action.

7.4 Which changeover method should be used?

Method	How it works	Advantage	Disadvantage
Direct changeover	Old system stops, new one starts immediately	Fast; cheapest; benefits are immediate	No fallback if the new system fails
Parallel running	Old and new systems run together	Old system is a backup; outputs can be compared	Costly; staff do the work twice
Pilot running	New system is used in one branch or department first	Failure affects only one area; staff there can train others	Slower to roll out everywhere
Phased implementation	One part (module) of the new system is introduced at a time	Problems are limited to one part	Takes a long time to complete

Choose by risk and cost in the scenario: a hospital or bank should avoid direct changeover; a small organisation with low-risk data may use it.

7.5 What goes in technical and user documentation?

Technical documentation only	Both	User documentation only
Program listing, program language, program flowcharts/algorithms, system flowcharts, file structures, list of variables, validation routines	Purpose of the system, limitations, hardware and software requirements, input format, output format, sample runs	How to load/run/install, save a file, print data, add, delete or edit records; error messages and error handling; troubleshooting guide/helpline; FAQs; glossary of terms

7.6 How is a new system evaluated?

• Judge the efficiency, ease of use and appropriateness of the solution.
• Compare the solution with the original task requirements.
• Identify limitations and necessary improvements.
• Evaluate the users’ responses to the results of testing the system.

Common mistakes and exam traps

• Calling out-of-range values (2 or 13 above) “extreme”. Extreme data is valid and is accepted.
• Saying validation makes data correct. It only checks that data is reasonable; verification checks it was copied accurately.
• Giving a list of research methods without linking an advantage or disadvantage to the scenario in the question.
• Describing pilot and phased implementation the same way. Pilot = one location gets the whole system; phased = everyone gets one part at a time.
• Putting “error messages” or “how to save a file” in technical documentation. These are for users.
• Writing “see if it works” for evaluation instead of “compare against the original requirements”.

Frequently asked questions

What are the six stages of the systems life cycle in IGCSE ICT 0417? Analysis, design, development and testing, implementation, documentation and evaluation. They form a cycle, because evaluation can identify improvements that start a new analysis.

What is the difference between extreme and abnormal test data? Extreme data is valid data on the boundary of the accepted range and should be accepted. Abnormal data is outside the range or of the wrong type and should be rejected.

Which implementation method is the safest? Parallel running, because the old system continues as a backup and outputs can be compared. It is also the most expensive, because the work is done twice.

Why is live data used after normal, abnormal and extreme data? Live data is real data whose results are already known, so it shows the system works in real conditions and gives the same results as the old system.

Self-test

1. Give one advantage of questionnaires over interviews.
2. Name the check that would stop a date being typed as 2026/11/08 when DD/MM/YYYY is required.
3. A field accepts 1 to 50. Give one extreme value and one abnormal value.
4. Which changeover method introduces the new system in one branch first?
5. Give two items found only in technical documentation.
6. State two things an evaluation compares or judges.

Answers: 1 many people at once / anonymous / quicker to analyse; 2 format check; 3 extreme 1 or 50, abnormal 0, 51 or text; 4 pilot running; 5 any two of program listing, flowcharts, list of variables, file structures, validation routines; 6 any two of efficiency, ease of use, appropriateness, comparison with requirements.

Official syllabus

Cambridge International, Cambridge IGCSE Information and Communication Technology (0417) syllabus for 2026, 2027 and 2028, Version 3, section 3 Subject content, Topic 7 “The systems life cycle” (7.1–7.6).