Describe the difference between primary and secondary storage.

Primary storage is directly accessible by the CPU, while secondary storage is not directly accessible and requires input/output channels.

Primary storage, also known as main memory, is the computer's working storage. It includes Random Access Memory (RAM) and cache memory. These types of storage are volatile, meaning they lose their contents when the power is turned off. The CPU can access data stored in primary storage directly and quickly, which is why it's used for tasks the computer is currently working on. However, primary storage is limited in size due to its cost and physical constraints.

Secondary storage, on the other hand, is not directly accessible by the CPU. Instead, it requires input/output channels to access and is used for storing data long-term. Examples of secondary storage include hard disk drives (HDD), solid-state drives (SSD), and optical disks. These types of storage are non-volatile, meaning they retain their contents even when the power is turned off. Secondary storage has a much larger capacity than primary storage and is typically slower to access.

The key difference between primary and secondary storage lies in their relationship with the CPU, their volatility, and their capacity. Primary storage is directly accessible by the CPU, is volatile, and has a smaller capacity. Secondary storage is not directly accessible by the CPU, is non-volatile, and has a larger capacity.

In terms of speed, primary storage is faster than secondary storage. This is because the CPU can access data in primary storage directly, without needing to go through input/output channels. However, because of its volatility, primary storage cannot be used for long-term data storage.

On the other hand, secondary storage is slower but provides a permanent solution for data storage. It's used for storing data that doesn't need to be accessed immediately or frequently, such as files, documents, and software.

A-Level Computer Science Tutor Summary: Primary storage, like RAM, is quick and directly linked to the CPU, used for immediate tasks but loses data when off. Secondary storage, such as hard drives, is for long-term use, holding data permanently but is slower to access. The main differences are how the CPU accesses them, their data retention (volatile or non-volatile), and their storage capacity.