1.3 Operating systems
Cambridge IGCSE ICT 0417 · Topic 1: Types and components of computer systems · Paper 1
6.9 Computers in the retail industry
Cambridge IGCSE ICT 0417 · Topic 6: ICT applications · Paper 1
7.4 Implementation
Cambridge IGCSE ICT 0417 · Topic 7: The systems life cycle · Paper 1
Say each word, then read what it means. Every one is in the glossary too.
Read it here, or open the study page below to go one step at a time with things to try.
An operating system (OS) is the system software that runs the computer. It is loaded when the computer starts.
It manages memory, files and folders, input and output devices, security (user accounts) and the running of programs.
It also gives the user an interface: the way the user and the computer communicate.
A command line interface (CLI) is text only. The user types commands, such as `copy report.docx backup`.
A graphical user interface (GUI) uses windows, icons, menus and a pointer (WIMP). Smartphones use a post-WIMP GUI where you tap and swipe instead of using a pointer.
| CLI | GUI | |
|---|---|---|
| Advantage | The user has direct control and can do things the GUI cannot; uses little memory and processing power | Easy to learn, no commands to remember, so good for beginners |
| Disadvantage | Must learn and remember commands; typing errors stop commands working | Uses more memory and processing power; some advanced settings are hidden |
| Typical user | Network manager, technician, programmer | Office worker, student, home user |
Compare both sides; a description alone is not enough. "A GUI is easier to use than a CLI because the user does not need to remember commands."
A dialogue-based interface lets the user talk to the computer. Voice assistants in phones, smart speakers and cars use it. The computer replies with speech.
A gesture-based interface reads body movements, such as a hand wave or a swipe in the air, using a camera or motion sensor. Games consoles and some cars use it.
| Dialogue-based (voice) | Gesture-based | |
|---|---|---|
| Advantage | Hands-free, so safer when driving; helps people with limited movement | No touching, so more hygienic (e.g. in a hospital); feels natural |
| Disadvantage | Background noise and accents cause errors; limited set of commands | Accidental movements can trigger commands; user must learn the gestures |
| Example | "Call home" in a car | Waving to skip a song on a car screen |
A point of sale (POS) terminal is the checkout till. It has a barcode reader, screen, keypad, receipt printer and cash drawer. It is linked to the shop's stock database.
An EFTPOS terminal (electronic funds transfer at point of sale) is the card reader at the till. It takes card payments.
| Advantages of card payment | Disadvantages of card payment |
|---|---|
| No need to carry large amounts of cash, which is safer | Card can be cloned or stolen; shoulder surfing of PIN |
| Faster for the shop; less cash to count and bank | Shop pays fees to the card company |
| Payments recorded, so easy to track spending | Fails if the network is down |
The shop's database stores each product's barcode number, name, price, stock level and re-order level (the number at which more must be ordered).
Shelves stay stocked without staff counting items, and the shop does not tie up money in too much stock.
Write "stock level is compared with the re-order level". "The computer knows it is low" gets no mark.
Contactless cards contain an RFID chip and antenna. The customer holds the card near the reader. Payments are limited to a set amount (often 50 euros), and the PIN is asked for every few payments.
NFC (near field communication) is a type of very short-range radio, usually under 4 cm. Phones and smartwatches use NFC to pay, pretending to be a contactless card.
Phone payments use tokenisation: a one-time code is sent instead of the real card number, and the user unlocks the phone with a fingerprint or face first.
| Advantages | Disadvantages |
|---|---|
| Very fast, so shorter queues | Stolen card can be used for small payments without a PIN |
| No PIN to be seen by shoulder surfing for small payments | Easy to spend without noticing |
| Phone payments are protected by biometrics and tokens | Criminals with a reader may try to read cards in a crowd |
Internet shopping also affects society: high-street shops close, there are fewer shop jobs but more warehouse and delivery jobs, and more vans on the roads.
| For customers | For businesses |
|---|---|
| Adv: shop 24/7 from home; no travel or parking | Adv: no expensive high-street shop needed; fewer staff |
| Adv: easy to compare prices and read reviews | Adv: can sell to customers worldwide |
| Adv: good for people with limited mobility | Adv: collect customer data to target offers |
| Disadv: cannot see or try goods before buying | Disadv: must pay for a secure website and delivery |
| Disadv: delivery costs and waiting; returns are a hassle | Disadv: strong competition; customers compare prices easily |
| Disadv: risk of fraud, fake sites and stolen card details | Disadv: risk of hacking and fake orders |
Implementation means putting the new system into use. Staff are trained and data from the old system is transferred.
Direct changeover: the old system stops and the new one starts at once, for example over a weekend.
Parallel running: the old and new systems both run at the same time, until the new one is trusted.
Pilot running: the new system is used in one branch or department first. Once it works, it goes to the rest.
Phased implementation: the new system is brought in one part at a time, across the whole organisation.
Pilot and phased are easy to mix up. Pilot = one place, whole system. Phased = whole organisation, one part at a time.
Each method trades cost and speed against risk.
The key question: what happens if the new system fails?
| Method | Advantages | Disadvantages |
|---|---|---|
| Direct | Cheapest: only one system runs and staff do the work once. Benefits are immediate. Fastest. | Highest risk: if the new system fails, there is no backup and work stops. Data could be lost. Staff must be fully trained before the switch. |
| Parallel | Lowest risk: if the new system fails, the old one is still working. Results can be compared to check the new system. | Most expensive: staff do every job twice, so extra staff or overtime are needed. Takes longest. Data entered twice can lead to errors. |
| Pilot | If it fails, only one branch is affected. Staff in the pilot branch can train others. Cheaper than parallel. | Slow to reach the whole organisation. If the pilot branch fails, it suffers on its own. The pilot branch may not be typical of the others. |
| Phased | If one part fails, only that part is affected and it can be fixed. Staff learn one part at a time. | Slow: takes a long time to fully implement. Parts of old and new systems must work together, which is hard. Costly to evaluate each phase. |
There is no best method. The right one depends on how bad a failure would be, how much money there is, and whether the system can be split into branches or parts.
Use direct when the system is small, simple, or the old system has already stopped working. Also when two systems cannot run side by side.
Use parallel when failure would be serious, such as payroll, banking or hospital records.
Use pilot when the organisation has many similar branches, such as shops or banks.
Use phased when the system splits into separate parts, such as a school system with attendance, marks and timetable modules.
In a 'choose and justify' question, the justification must link to the scenario. 'Parallel is safest' is weak. 'Parallel, because if the new payroll fails, 300 staff still get paid by the old system' is strong.
There is something to try for this step in the IGCSE library.
Open the study page and go one step at a time.
Step by step, with exam questions and a quiz.
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ICT topic 10Step by step, with exam questions and a quiz.
Topic 1 · Year 7A computer takes information in, follows instructions to change it, and gives a result out. It does all of this with billions of tiny on/off switches.
One question at a time. The reason shows after each answer.