Primary Storage

This lesson covers primary storage — the memory that the CPU can access directly, including RAM, ROM, cache and virtual memory. For the OCR H446 exam, you must understand how each type works, the differences between SRAM and DRAM, the cache hierarchy, and the role of virtual memory.

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What Is Primary Storage?

Primary storage (also called main memory or internal memory) is memory that the CPU can access directly via the system bus. It includes RAM, ROM and cache. Primary storage is fast but generally volatile (except ROM) and limited in capacity compared to secondary storage.

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RAM — Random Access Memory

RAM is volatile — it loses all its contents when the power is switched off. It stores the currently running programs and data that the CPU needs to access quickly.

DRAM (Dynamic RAM)