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ROM and RAM Explained

The ability of a computing system to store and retain information (memory) is essential because, without it, the computer would not be able to carry out simple tasks. There are two basic types of computer memory: primary memory and secondary memory. Examples of secondary memory devices include hard drives, CDs, etc.

On the other hand, the primary memory is subdivided into RAM and ROM, and these two are what we’ll focus on in this article. Although the acronyms ROM and RAM are commonly used in today’s modern society, very few persons understand the functions that these memory types carry out in detail.

Let’s consider them briefly.

Random Access Memory (RAM)

RAM is also called the main memory or primary volatile memory. Amongst the many differences between the RAM and ROM, the most significant of all is their storage capabilities, otherwise known in this context as their volatilities. The RAM chip is volatile; once the power is turned off, it automatically loses any information it is holding.

As such, the RAM chip requires a constant supply of power to retain whatever information is stored. Due to its volatility, RAM is used for the temporary storage of files used on the computer like a document being worked on, an image being edited, or a game being played. RAM is further subdivided into SRAM (Static Random Access Memory) and DRAM (Dynamic Random Access Memory).

Read-Only Memory (ROM)

ROM is also known as the primary non-volatile memory. Unlike RAM, ROM is non-volatile; it does not need a constant power supply to retain the information stored on it. In contrast to RAM also, ROM is used for the permanent storage of crucial information necessary to operate the computer. One of the primary purposes that the ROM chip serves is running the computer’s start-up process.

It can do this by storing the BIOS program on the motherboard. ROM chips are also mostly used in gaming system cartridges and calculators. Just like RAM, ROM can be further classified into three types: PROM (Programmable Read-Only Memory), EPROM (Erasable Programmable Read-Only Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory).

For easy reference purposes, we have compiled the major features/differences of ROM and RAM in bullets points below:


  • Temporary storage
  • Volatile
  • Used in normal computing operations
  • Stores data in Gigabytes


  • Permanent storage
  • Non-volatile
  • Used in the booting process of a computer
  • Stores data in Megabytes