Primary Storage

Primary Storage is data storage in random access memory (RAM) and other "built-in" devices. It is a type of semiconductor memory. Technically known as memory or internal memory, primary storage is directly connected to the central processing unit of the computer. It must be present for the CPU to function correctly. Modern primary storage devices include – Random access memory (RAM) including VRAM, WRAM, NVRAM, and Read-only memory (ROM).
Primary storage typically consists of three kinds of storage – Processor registers, Cache memory, Main memory. Internal to the central processing unit, processor registers have information that the arithmetic and logic unit needs to carry out the current instruction. Cache memory is a special type of internal memory used by many central processing units to increase their performance or "throughput". Main memory is the electronic solid-state random access memory, which is directly connected to the CPU via a "memory bus" and a "data bus".