Difference between ROM and RAM

What is RAM?

RAM stands for random access memory. This is also called temporary memory. RAM is used to store data and programs that are used by the processor in real-time. Data on RAM can be erased, read, and write at any time.

Data stored in RAM is temporary and is automatically erased when the computer is turned off.

Types of RAM:

There are basically two types of RAM as follows:

  • SRAM:

SRAM stands for stable random access memory. SRAM stores data using the state of six transistor memory cells.

  • DRAM:

DRAM stands for Dynamic Random Access Memory. DRAM stores the data using capacitors and transistors.

Difference between DRAM and SRAM:


  • SRAM is a one chip memory.
  • The data access time of SRAM is faster than DRAM.
  • SRAM Storage capacity is less than DRAM.
  • SRAM is expensive than DRAM.


  • DRAM is an off chip memory.
  • The data access time of DRAM is slower than SRAM.
  • DRAM storage capacity is more than SRAM.
  • DRAM is cheaper than SRAM.

What is ROM?

ROM stands for read-only memory, it is also known as permanent memory. ROM is a type of electronic storage that comes built into a device during manufacturing.

You can find ROM chips in your computers and many other types of electronic products such as car radios, VCRs, and digital watches.

ROM is a volatile memory which means it remains viable even when your computer / device is off.

Types of ROM:

There are basically five types of ROMs. Let’s discuss in detail one by one.

  • PROM:

PROM stands for programmable read-only memory. Data is stored in PROM is only once and cannot be changed or deleted.

An example of a PROM is the BIOS in older computers. But now PROM has been replaced by EEPROM.

  • EPROM:

EPROM stands for Erasable Read only memory. It’s a second type of Read Only Memory. The data remains constant even when there is no power supply in the EPROM.

Data can be reprogrammed and erased in EPROM using ultraviolet (UV) light. UV light erases the data on the chip, so we can reprogram the data in it.


EEPROM stands for electrically erasable programmable Read Only Memory. The principle process of EEPROM is similar to that of EPROM, which we mentioned above, but the way to write and erase data by exposing it to electrical charge.

Data can be reprogrammed in EEPROM, about 10,000 times.

EEPROM allows the user to program and delete data at any location in the memory, but the data erased by one byte at once instead of erasing the entire chip. That’s why the reprogramming process can be a bit slow.

  • Flash Memory:

Flash memory is a modern type of EEPROM. Compared to normal EEPROM, the speed of rewriting and deleting data from flash memory is faster.

Flash memory is a distinct type of EEPROM, which is programmed to erase the large block of data at once.

It is also used to transfer data between different devices.

Difference between RAM and ROM:

The key differences between RAM and ROM are as follows:


  • RAM stands for Random. only Memory
  • RAM is a volatile memory, which means that the data is stored as long as the power is supplied.
  • The data is stored in RAM can be altered and retrieved.
  • Data processing speed of RAM is faster than ROM.
  • The data stored in RAM is easily accessible.
  • CPU can access the data directly to the RAM.
  • RAM is used as a CPU cache memory.
  • The physical size of the ROM is usually larger than the RAM. It usually comes in two different sizes for laptops and computers. Laptop RAM is 3 inches long and 1 inch wide. However, the desktop RAM is 6 inches long and about 1 inch wide.
  • Its more expensive than ROM.
  • Types: SRAM (Static Random Access Memory), DRAM (Dynamic Random access Memory).


  • ROM stands for Read only Memory.
  • ROM is a non-volatile memory, which means that the data is stored until the power is turned off.
  • The data is stored in ROM can only be read.
  • Data processing speed of ROM is slower than RAM.
  • The data stored in ROM is not easily accessible.
  • CPU cannot access data directly to the ROM unless the data is stored in RAM.
  • ROM is used as firmware by microcontrollers.
  • Its size limits are usually smaller than RAM based on storage capacity.
  • Its size limits are usually smaller than RAM based on storage capacity.
  • It’s cheaper than RAM.
  • Types: PROM (programmable read-only memory), EPROM (Erasable Read only memory), EEPROM (electrically erasable programmable Read Only Memory), Flash Memory, MROM (Mask Read Only Memory).

Bottom Line:

Both ROM and RAM are essential memories for a computer. RAM is required for CPU processing and RAM is required to boot up the computer.

See Also
What is DBMS
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