System components (Cambridge International AS Computer Science)
Exam board Cambridge International · ASUpdated 2025-04-07
Input/output devices
What is an input device?
- Input devices are hardware components that allow users to interact with a computer system
- They enable the user to input data or commands into the system, which the computer then processes to produce output
Types of input devices
| Name of device | Description |
|---|---|
| Keyboard | The most common input device. It allows users to input text and commands by pressing keys |
| Mouse | Allows users to navigate the computer screen, click on items, and perform other functions |
| Touchscreen | Found on smartphones, tablets, and some computers, touchscreens allow users to interact with the device by touching the screen |
| Microphone | Captures audio input, which can be used for voice commands, recording audio, or video conferencing |
| Webcam | Captures video input, often used for video conferencing or recording videos |
| Scanner | Digitises physical documents or images, converting them into a format that the computer can process |
| Game Controller | Used primarily for video games, these devices allow users to control game characters and interact with the gaming environment |
| Graphics Tablet | Allows artists and designers to draw or sketch directly onto a computer. It's particularly useful for graphic design, 3D modelling, and other visual creative tasks |
| Biometric Devices | These devices, such as fingerprint scanners or facial recognition systems, are used for security purposes to verify a user's identity |
| Barcode Reader | Scans barcodes, typically used in retail and inventory management |
| Joystick | Often used for computer games, especially flight simulators. It allows the user to control movement more fluidly than with a keyboard or mouse |
What is an output device?
- Output devices are hardware components that receive information from a computer system and present it to the user in a comprehensible form
- They enable the computer to communicate the results of processed data or commands
Types of output devices
| Name of device | Description |
|---|---|
| Monitor | This is the most common output device. It displays visual output from the computer, including text, images, and videos |
| Printer | Produces a hard copy of digital documents or images. There are various types of printers, including inkjet, laser, and 3D printers |
| Speakers | Output audio from the computer, such as music, sound effects, or voice |
| Headphones | Similar to speakers, headphones output audio directly to the user, providing a more personal and potentially immersive experience |
| Projector | Projects the computer's display onto a large screen or wall, useful for presentations or movie viewing |
| Braille Display | This specialised device outputs information in Braille, allowing visually impaired users to read text from the computer |
| Plotter | Used for printing large, high-quality diagrams and designs, often used in engineering or architecture |
| Virtual Reality (VR) Headset | Provides an immersive visual and audio output, primarily used for gaming and virtual simulations |
| Computer-Controlled Machinery | In manufacturing or robotics, computers often output commands directly to machinery to control their operation |
Choosing the right device
When recommending a device for a specific situation, consider the following factors:
-
User Needs
- What tasks will the user be performing? A graphic designer might need a graphics tablet, while a data entry clerk might need a keyboard with a number pad
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User Skills
- Is the user comfortable with the device? A touch screen might be more intuitive for some users, while others might prefer a mouse and keyboard
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Environment
- Where will the device be used? A wireless mouse might be suitable for a clutter-free office, while a wired mouse might be better for a public computer lab to prevent theft
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Cost
- Higher-end devices often have more features but are also more expensive. Consider the budget and whether the extra features are worth the cost
Primary memory
Spec point —
3.1.1
What is primary memory?
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Primary memory is memory directly accessible by the CPU
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Has much faster access times than secondary storage
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This speeds up operations like the Fetch-Execute Cycle
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Stores data and instructions the CPU needs while the computer is on and running
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Acts as short-term, working memory
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Found in components like:
- RAM (Random Access Memory) – directly connected to the CPU
- Cache and Registers – built into the CPU for even faster access
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Because it’s fast, it’s also more expensive, so we use less of it
- Example: RAM = 16–32 GB
- Secondary storage (like HDDs) = 1–2 TB or more
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View more detailed information on the different types of memory
Secondary storage
What is secondary storage?
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Secondary storage provides permanent data storage
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Hardware components that retain digital data within a computer system
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They provide a means of storing, accessing, and retrieving data, which can include software applications, documents, images, videos, and more
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There are 3 types of storage:
- Magnetic
- Optical
- Solid state
| Type of storage | Description | Benefits | Drawbacks |
|---|---|---|---|
| Magnetic(e.g., Hard Disk Drives, Magnetic Tape Drives) | Store data by magnetising particles on a disk or tape | High storage capacity; relatively low cost per gigabyte; suitable for long-term storage and backup | Slower read/write speeds compared to other types; susceptible to physical damage; moving parts can wear out over time |
| Optical(e.g., CDs, DVDs, Blu-ray Discs) | Store data using a laser to burn pits into the surface of the disc | Durable and relatively immune to environmental conditions; easy to transport; suitable for distributing software, music, or movies | Lower storage capacity compared to other types; slower read/write speeds; can be easily scratched or damaged |
| Solid state(e.g., Solid-State Drives, USB Flash Drives) | Store data in flash memory cells | Fast read/write speeds; no moving parts, so less likely to fail due to physical shock; silent operation | Higher cost per gigabyte; flash memory cells can wear out after a certain number of write cycles |
Here are some of the devices commonly used for storage:
| Name of device | Type of device | Typical storage capacity | Affordability | Portability | Durability |
|---|---|---|---|---|---|
| Hard Disk Drive (HDD) | Magnetic | 500GB - 2TB (consumer-grade) | Low cost per GB | Low (especially for internal HDDs) | Moderate (susceptible to damage from shocks or falls due to moving parts) |
| Solid-State Drive (SSD) | Flash | 120GB - 4TB (consumer-grade) | High cost per GB | High (especially for external SSDs) | High (no moving parts, less susceptible to physical shock) |
| USB Flash Drive | Flash | 8GB - 256GB (common sizes) | Moderate cost per GB | Very High (small and lightweight) | Moderate (can withstand casual handling, but can be lost or damaged if not cared for) |
| CD/DVD/Blu-ray Disc | Optical | CD: 700MB, DVD: 4.7GB - 9GB, Blu-ray: 25GB - 50GB | Low cost per disc | High (thin and lightweight) | Low (can be scratched or damaged easily) |
Choosing the right storage device
When recommending a storage device for a specific situation, consider the following factors:
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Storage needs
- How much data does the user need to store? A user with large amounts of data might need a high-capacity HDD, while a user who only needs to store a few documents might be fine with a USB flash drive
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Performance needs
- Does the user need fast access to their data? An SSD might be best for tasks that require high-speed data access, like video editing or gaming
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Portability
- Does the user need to transport the data? USB flash drives and external HDDs or SSDs are portable and can be used to transfer data between different computers
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Cost
- Higher-capacity and faster storage devices are generally more expensive
- Consider the user's budget and whether their storage and performance needs justify the extra cost
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