Types and components of computer systems
Hardware and software, the main parts of a computer, operating systems and their interfaces, types of computer, and emerging technologies such as AI and extended reality.
📌 Key points
- Hardware is the physical parts of a computer (e.g. motherboard, CPU, RAM, graphics card, sound card, NIC, monitor, keyboard); software is the programs that tell the hardware what to do.
- Application software lets the user do tasks (word processing, spreadsheets, database management, photo, video and audio editing, graphics, CAD, control and measurement); system software runs the computer (operating system, device drivers, utilities, compilers, linkers).
- The CPU interprets and executes instructions and processes data. RAM is volatile, stores the data and programs currently in use, and can be read from and written to; ROM is non-volatile, read-only, and stores the instructions needed to start the computer.
- Backing storage (e.g. hard disk, SSD) keeps data and programs permanently when the power is off; it has a much larger capacity than RAM but is slower to access.
- An operating system manages the hardware and provides a user interface. A command line interface (CLI) needs typed commands: fast for experts and uses little memory, but commands must be learnt. A graphical user interface (GUI) uses windows, icons, menus and a pointer: easy for beginners but uses more memory and processing power.
- Other interfaces include dialogue-based (spoken commands, e.g. in a car) and gesture-based (hand movements detected by a camera or sensor).
- Desktop computers are powerful, easy to upgrade and have full-size keyboards and screens, but are not portable; mobile computers (laptops, tablets, smartphones, phablets) are portable with built-in batteries and Wi-Fi, but have smaller screens and keyboards, limited battery life and are easier to lose or steal.
- Artificial intelligence (AI) is when a computer simulates human intelligence, e.g. chatbots, voice assistants and facial recognition. Extended reality includes virtual reality (a fully computer-generated world seen through a headset) and augmented reality (computer images added on top of a view of the real world).
- Data from the real world (e.g. temperature) is analogue and must be converted to digital data by an analogue-to-digital converter (ADC) before a computer can process it.
📖 Key terms
- Hardware
- The physical components of a computer system.
- Software
- The programs that control the operation of a computer.
- RAM
- Volatile memory holding the data and programs currently in use; can be read and written.
- ROM
- Non-volatile, read-only memory that stores the start-up instructions.
- Backing storage
- Secondary storage that keeps data permanently when the computer is switched off.
- Graphical user interface (GUI)
- An interface that uses windows, icons, menus and a pointer.
- Augmented reality
- Computer-generated images placed on top of a real-world view, e.g. through a phone camera.
✏️ Worked example
Describe three differences between RAM and ROM.
- RAM is volatile (its contents are lost when the power is off), whereas ROM is non-volatile.
- RAM can be read from and written to, whereas ROM can only be read.
- RAM stores the programs and data currently in use, whereas ROM stores the start-up instructions.
- RAM usually has a much larger capacity than ROM in a computer.
When comparing two things (RAM/ROM, CLI/GUI, desktop/laptop), make each point a direct comparison using "whereas". Describing only one of the two usually earns half the marks.
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