In simple terms
A friendly intro before the formal notes — no formulas yet.
Building a System: Blueprint and User Manual
Designing a computer system is like planning a new kitchen. You need to choose the right appliances (components), make sure it's easy to cook in (usability), and have instructions for everything (documentation).
Imagine you're setting up a home cinema. You need a TV, speakers, and a streaming device (the components). It needs to be easy for anyone in the family to turn on and find a film (usability). Finally, you'll have the manuals for the TV and speakers (technical documentation) and maybe a simple one-page guide you wrote for your grandparents (user documentation). A well-designed system considers all these aspects from the start.
- 1
Identify Components: List all the necessary parts: hardware (like a server), software (the operating system), peripherals (printers), and the people who will use and maintain it.
- 2
Define Usability Goals: Determine how to make the system easy to learn, efficient to use, and satisfying for the end-users. This includes considering accessibility for all users.
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Plan Documentation: Decide what information is needed for users (how to use it) and for developers or technicians (how it works and how to fix it).
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Integrate and Test: Assemble the components, test how they work together, and get feedback from real users to check if usability goals have been met.
Explore the concept
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Full topic notes
Formal explanation with the rigour you need for the exam.
The Components of a Computer System
A computer system is more than just the machine on your desk or the phone in your hand. It's a complex interplay of various elements working together to achieve a specific goal. In IB Computer Science, we categorise these into five main groups. Understanding each component and how it relates to the others is the first step in designing or analysing any system, from a simple mobile game to a global banking network.
Hardware: The physical parts of the system you can touch. This includes the central processing unit (CPU), memory (RAM), storage (SSD/HDD), and motherboard.
Software: The set of instructions that tells the hardware what to do. This includes the operating system (e.g., Windows, macOS, Android) and application software (e.g., a web browser, a word processor).
Peripherals: Auxiliary input, output, and storage devices connected to the computer. Examples: keyboard, mouse, monitor, printer, external hard drive.
Network: The communication infrastructure connecting systems and allowing them to share resources. This can be a Local Area Network (LAN) in a school, or a Wide Area Network (WAN) like the internet. It includes routers, switches, and cabling.
Human Resources: The people who use, manage, and maintain the system. This is a critical component, encompassing end-users, system administrators, developers, and trainers.
Usability: Designing for Humans
Usability is a quality attribute that assesses how easy a user interface is to use. It's not just about aesthetics; it's a scientific approach to making systems effective, efficient, and satisfying. A system with high usability allows users to accomplish their tasks with minimal friction and frustration, while a system with low usability can lead to errors, abandonment, and financial loss. The International Organization for Standardization (ISO 9241-11) provides a useful framework for defining and measuring usability.
Effectiveness: Can users successfully achieve their goals with accuracy and completeness? For example, can a user successfully book the correct flight on a travel website?
Efficiency: How much effort (time, clicks, cognitive load) does it take for users to achieve their goals? For example, how many steps and how long does it take to complete the flight booking?
Satisfaction: How do users feel about their experience? Is it pleasant, frustrating, or neutral? This is often measured with post-use questionnaires.
Accessibility: Can people with disabilities (e.g., visual impairments, motor difficulties) use the system? This involves features like screen reader compatibility, keyboard navigation, and sufficient colour contrast. Accessibility is a vital component of inclusive usability.
The Critical Role of Documentation
Documentation is the collection of texts and diagrams that explains how a system works or how to use it. It is a common point of failure in many projects, but when done well, it is essential for a system's long-term success, maintainability, and usability. We broadly categorise documentation into two types, each serving a very different audience and purpose.
User Documentation: This is aimed at the end-user and focuses on what the system does and how to perform tasks. It should be written in clear, non-technical language. Examples include user manuals, online help systems, tutorials, and Frequently Asked Questions (FAQs).
Technical Documentation: This is for developers, system administrators, and maintenance teams. It focuses on how the system is built and why specific design decisions were made. It is highly technical and includes system architecture diagrams, API documentation, code comments, database schemas, and test plans.
In Paper 1, when asked to evaluate a system described in a scenario, don't just focus on the hardware and software. A common scenario involves a technically advanced system that is failing. The marks are often found by analysing the human side: poor usability, inadequate training (a 'Human Resources' issue), or unclear user documentation. Always consider the interaction between all five system components.
Worked examples
See the formulas applied — reveal one step at a time, like the exam.
A school is implementing a new online library system for students to borrow e-books. Identify the five key components of this system and provide a specific, relevant example for each.
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A correct response must link each component to the specific context of the school library system.
A new point-of-sale (POS) system is installed in a busy cafe. After one month, staff are making frequent errors, and customer queues are longer than with the old system. The new system has a modern touchscreen and more features. Using the concepts of usability, explain two likely reasons for these problems, justifying your answer.
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The question requires an explanation linked to usability concepts.
How it all connects
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Glossary
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Quick check
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Revision flashcards
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What are the five key components of a computer system?
Hardware, Software, Peripherals, Network, and Human Resources.
Key takeaways
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Hardware: The physical parts of the system you can touch. This includes the central processing unit (CPU), memory (RAM), storage (SSD/HDD), and motherboard.
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Software: The set of instructions that tells the hardware what to do. This includes the operating system (e.g., Windows, macOS, Android) and application software (e.g., a web browser, a word processor).
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Peripherals: Auxiliary input, output, and storage devices connected to the computer. Examples: keyboard, mouse, monitor, printer, external hard drive.
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Network: The communication infrastructure connecting systems and allowing them to share resources. This can be a Local Area Network (LAN) in a school, or a Wide Area Network (WAN) like the internet. It includes routers, switches, and cabling.
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Human Resources: The people who use, manage, and maintain the system. This is a critical component, encompassing end-users, system administrators, developers, and trainers.
Practice — then mark it
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Test your knowledge with exam-style questions on System Design Basics.
Test your knowledge with exam-style questions on System Design Basics.
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Frequently asked
Checkpoint
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