Memory Storage in computers is essential for storing data and instructions for executing the processes. It can be classified into different types based on speed, volatility, and accessibility.

1. CPU Register: These high-speed registers in the CPU serve as working memory for instruction and temporary storage of data. Typically, they create a general-purpose register file. The capacity of 32 data words is typical of a register file, and each register can be read or written from within a single clock cycle.

2. Cache Memory: These are positioned logically between the CPU registers and main memory, it is typically divided into levels (L1, L2, L3) based on proximity to the CPU. The storage capacity of a cache is less than that of the main memory but with an access time of one to three cycles. Unlike the other three types of memory, the cache is usually transparent to programmers.

3. Main or Primary Memory: The memory directly accessible by the CPU is used to store data and instructions that are actively being processed. Primary memory is typically volatile, meaning it loses its contents when the power is turned off. It can be further divided into:

• Dynamic RAM (DRAM): This type of RAM stores data in capacitors and requires periodic refreshing to maintain the data. It is commonly used as the main memory in computers due to its cost-effectiveness.
• Static RAM (SRAM): SRAM uses flip-flops to store data, which makes it faster and more reliable than DRAM. However, it is more expensive and is typically used for cache memory.

4. Secondary Memory: Also known as auxiliary memory or external memory, is used for long-term data storage. Unlike primary memory, secondary memory is non-volatile, meaning it retains data even when the power is turned off. It is generally slower than primary memory but provides a much larger storage capacity. Common types of secondary memory include Hard Disk Drives (HDD), Solid State Drives (SSD), Optical Discs, and USB Flash Drives.

5. Virtual Memory: Virtual memory is a memory management capability that allows the execution of processes that may not be completely in the physical RAM. It uses a portion of the hard drive as an extension of RAM.

6. ROM (Read-Only Memory): ROM is a non-volatile memory that retains its contents even when the power is off. It is used to store firmware and system instructions that do not change frequently. A few variants of ROM include PROM (Programmable ROM), EPROM (Erasable Programmable ROM) and EEPROM (Electrically Erasable Programmable ROM).