Difference Between RAM and ROM

Edited by Diffzy | Updated on: October 12, 2023


Difference Between RAM and ROM

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In a computer system, the CPU (Central Processing Unit) is the real brain behind all the processing. It interprets instructions and carries out operations via memory. Memory in a computer system is broadly divided into two categories: Primary or Internal Memory and Secondary or External Memory.

Primary or Main Memory has two subtypes that are, RAM and ROM. Primary memory holds programs and data during processing. RAM refers to Random Access Memory, and ROM refers to Read-only Memory.

RAM and ROM are referred to as Immediate Access Storage (IAS) because the CPU can access the data quickly compared to data in secondary memory. Let’s learn more about RAM and ROM in this topic through their distinct characteristics.


RAM is an abbreviation of Random Access Memory. It is a hardware element used to store programs and data that are used by the CPU. RAM is volatile that is, its content becomes lost when the device is powered off. This memory is read, write memory. RAM is used as Cache Memory, which provides high-speed data access to a processor.

ROM is an abbreviation of Read-only Memory. It is non-volatile. That is, its content is retained even when the device is powered off. ROM is also called firmware, an integrated circuit. It benefits the microcontrollers that are used in monitors, keyboards, and other electronic devices.

In RAM, information is stored electrically on transistors when there is no electric current. But ROM does not depend on an electric current to save data. That’s why users can easily access the stored information in RAM, whereas information stored in ROM cannot be directly accessed. RAM has limited storage capacity compared to ROM, which is why RAM needs Auxiliary memory.

Difference Between RAM and ROM in Tabular Form

Full FormRandom Access MemoryRead-only Memory
FeatureIt is a temporary memory of the computer.It is the permanent memory of the computer.
DefinitionRAM is a form of data storage that can be accessed randomly at any time, in any order by the CPU.ROM is a form of data storage that generally stores instructions and is stored as a form of circuit for the computer to start initially.   
StructureRAM is in the form of a chip.ROM is generally an optical driver, made of magnetic tapes.
ComponentsRAM consists of four components-Matrix, Address decoder, Input buffer, and Output buffer.ROM consists of two components-Decoder and OR gates.
TypesRandom Access Memory is of two types: SRAM (Static Random Access Memory), DRAM (Dynamic Random Access Memory)Read-only Memory is of four types: MROM (Masked ROM), PROM (Programmable ROM), EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM)
Used asUsed as CPU Cache, Primary Memory in a computer.Used as Firmware by micro-controllers.
SizeLarger than ROM.Smaller than RAM.
SpeedRAM chips can read data faster.ROM is slower in reading the data than RAM.             
Storage CapacityIt ranges from 1 to 256 gigabytes (GB).It ranges from 4 to 8 Mega Bytes (MB).
VolatilityRAM is volatile.ROM is non-volatile.
OperationsIt allows reading and writing.It only allows reading.
InterchangeableRAM contents can be changed when required.ROM cannot be easily interchanged or reprogrammed.                           
FunctionsRAM allows computers to read data quickly to run applications.ROM stores programs that are needed to boot the computer initially.

What is RAM?

Random Access Memory is a kind of internal memory of the CPU for holding data and programs. It is a volatile memory that can be changed or upgraded easily by the users. In RAM, transistors are used to store data depending upon electricity.

RAM can be found in computers and printers. This memory is measured in megabytes, and its speed is measured in nanoseconds.

Types of Random Access Memory (RAM)

SRAM (Static Random Access Memory)

SRAM is also called semiconductor memory, used to store data from end to end. It is faster and needs less power for processing. SRAM is highly expensive and does not need to be refreshed like DRAM.

Static RAM uses a matrix of six transistors and no capacitors. It is used as cache memory in the system.

DRAM (Dynamic Random Access Memory)

DRAM is highly used as a computer’s main memory. It must be continuously refreshed; otherwise, all contents are lost.

DRAM is built of one capacitor and one transistor. Mostly, DRAM is used because it is cheap and small.

Advantages of RAM

In the Gaming world, RAM with enough size is important. RAM quickly delivers the data to the users, and it also stores more data than ROM.

What is ROM?

Read-only Memory is a memory from which data can be read-only, but rewriting is not possible. ROM is non-volatile that is, its content is retained even when the device is powered off. Non-volatile memory cannot be changed by the users.

ROM possesses BIOS (Basic Input Output System), that runs only when a computer is turned on.

Types of Read-only memory (ROM)

  1. MROM (Masked Read-only memory) – Its content can be programmed only by an integrated circuit manufacturer. MROM does not allow users to alter the stored data within it.
  2. PROM (Programmable ROM) – This type of ROM can be customized with a unique tool called a PROM programmer. It modifies fuses in memory cells to store the necessary data.
  3. EPROM (Erasable Programmable ROM) – It is used to store the computer BIOS. EPROM can be rewritten by using UV radiation.
  4. EEPROM (Electrically Erasable Programmable ROM) – It can be electrically rewritten and is not removed from the computer. It stores and deletes instructions on a special circuit.

Advantages of ROM

Read-only memory stores many important processes that are necessary to run the computer. It is also cheaper per gigabyte than RAM.

Main Difference Between RAM and ROM (In Points)

  • RAM refers to Random Access Memory, and ROM refers to Read-only Memory.
  • Random Access Memory is of two types: SRAM and DRAM. On the contrary, Read-only Memory is of four kinds: MROM, PROM, EPROM, and EEPROM.
  • RAM is a temporary memory, but ROM is a permanent memory of the computer system.
  • RAM is up to some Giga Bytes (GB), and ROM is up to some Megabytes (MB).
  • RAM is more significant than ROM, whereas ROM is smaller but large enough to hold basic instructions.
  • RAM chips can read data faster than ROM.
  • Random access memory allows reading and writing, but Read-only memory allows only reading.
  • RAM has limited storage capacity in comparison to ROM, which is why RAM requires Auxiliary memory.
  • RAM is volatile. That is, its content becomes lost when the device is powered off, while ROM is non-volatile. That is, its content is retained even when the device is powered off.
  • RAM is used as CPU Cache, Primary Memory in a computer, whereas ROM is used as Firmware by micro-controllers.
  • RAM is expensive in comparison to ROM and other memories.


It's time to conclude this topic, which is the difference between RAM and ROM. RAM and RAM both belong to main memory or primary or internal memory. These are in-built chips that play a vital role and help in the processing of a computer system. Individually, both RAM and ROM possess distinct characteristics that make them different.


  • https://www.javatpoint.com/ram-vs-rom
  • https://www.scaler.com/topics/ram-and-rom

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"Difference Between RAM and ROM." Diffzy.com, 2024. Sun. 14 Jul. 2024. <https://www.diffzy.com/article/difference-between-ram-and-rom>.

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