Know and understand solid-state media including memory cards (SD, xD, CFast)

3 Storage devices and media

Solid‑state media – the basics

Solid‑state media use flash memory, which is like a tiny digital backpack that never gets dusty or broken by bumps. Because there are no moving parts, they are faster, quieter and more reliable than magnetic hard drives.

Think of it as a library where books (data) are stored on shelves (memory cells). The librarian (controller) can fetch any book instantly, no matter where it is.

Memory cards – the everyday flash

Memory cards are small, portable flash storage devices that fit into cameras, phones, drones and more. The most common types are SD, xD and CFast.

📸 Analogy: Think of an SD card as a tiny library that can hold thousands of books (photos). An xD card is like a small photo album that was popular in the early 2000s. CFast is a super‑fast courier that can deliver a whole movie in seconds.

Why speed matters

Speed is measured in write/read rates and is crucial for video recording. The higher the speed class, the smoother the video and the less chance of dropped frames.

$$\text{Speed} = \frac{\text{Data (MB)}}{\text{Time (s)}}$$

Exam tip boxes

📌 Exam Tip: Remember that solid‑state media have no moving parts, which makes them faster and more reliable than magnetic drives. Use this fact when answering questions about performance and durability.

📌 Exam Tip: When comparing SD, xD and CFast, focus on speed class and capacity range. For example, CFast is best for high‑resolution video because it can write at 1 GB/s, whereas xD is limited to 30 MB/s.

📌 Exam Tip: Use analogies to explain concepts. For instance, describe an SD card as a “tiny library” to help remember its role as a portable storage container.