Distinguish between in primary and secondary memory?

Memory can be categorized in different ways by technology or properties: primary access by the CPU or secondary (indirect) access by the CPU. This distinction is primarily based on the speed of access to the memory. volatile or non-volatile is a distinction based on technology (magnetic vs. electrical, etc.). Volatile memory requires power to maintain its stored information. Read-only memory, or read-write is a distinction based on properties of the memory. Read only memory, or "ROM", is not modifiable.