Primary Storage

Primary	Secondary
Volatile (with the exception of ROM)	Non-volatile
Small capacity	Large capacity

A computer needs primary storage because access times are considerably faster than secondary
This means the time taken to complete operations such as the Fetch-Execute Cycle is dramatically reduced
Primary storage holds the data and instructions that the CPU needs to access whilst the computer is turned on
Due to the fast access times, primary storage is used as short-term, working memory, in hardware that is directly connected to the CPU such as RAM, and components that reside inside the CPU such as Cache and Registers
Performance of primary storage means a much higher cost which limits the amount that is used
For example, RAM is commonly purchased in 16 or 32 gigabytes whereas secondary storage such as a hard drive is in terabytes

RAM (Random Access Memory) is primary storage that is directly connected to the CPU and holds the data and instructions that are currently in use
RAM is volatile which means the contents of RAM are lost when the power is turned off
For the CPU to access the data and instructions they must be copied from secondary storage
RAM is very fast working memory, much faster than secondary storage
RAM is read/write which means data can be read from and written to
In comparison to ROM, it has a much larger capacity

ROM (Read Only Memory) is primary storage that holds the first instructions a computer needs to start up (Bootstrap)
ROM contains the BIOS (Basic Input Output System)
ROM is a small memory chip located on the computers motherboard
ROM is fast memory, much faster than secondary storage but slower than RAM
ROM is non-volatile which means the contents of ROM are not lost when the power is turned off
ROM is read only which means data can only be read from
In comparison to RAM, it has a much smaller capacity

RAM