RAM and ROM – Types, Difference, Advantage and Disadvantages

Memory is the most important part of a computer system since the computer cannot perform basic tasks without it. The primary memory consists of RAM and ROM.

In this article, we will go through computer memory, i.e. RAM and ROM, primary memory, types of memory in the computer, the difference between RAM and ROM, What RAM and ROM stand for, and other details.

Related Article: How to check what kind of RAM I have?

Must Read:- Uses of Computer


What is RAM and ROM in a Computer?

Computer memory is any physical device that can temporarily store information, such as RAM (Random Access Memory), or permanently, such as ROM (Read-Only Memory).

Memory devices use built-in circuits and are used by operating systems, applications, and hardware.

What is RAM in a computer?


Volatile storage is a memory that loses its contents if the device or computer loses its power. RAM is volatile high-speed memory.

When applications for software, records, and files are opened, they are copied from secondary storage into RAM. They remain in RAM until we close the files or applications.

The operating system is copied from the secondary storage to the RAM when a computer boots up. This is the reason you lose something that hasn’t been saved if your computer crashes or restarts while you work on a program.

Non-volatile memory is a memory that holds its contents even though control is lost.

What is ROM in a computer?

Difference between RAN and ROM

ROM stands for Read-Only memory.  It is a permanent memory, where programs are stored while a computer is being created.

Unable to modify and erase stored programs in this memory, they can only be read. Therefore, this memory is called read-only memory.

Also after the device is turned off, the data contained in ROM will not be destructed. Hence, ROM is also called non-volatile memory.

Difference between RAM and ROM memory

Random Access Memory allows the computer to read data quickly and efficiently so that programs can be run effectively, while Read-Only Memory stores the software required to initially boot the machine and perform diagnostics.

RAM is a popular form of memory used in computers and printers, which can be as large as a few gigabytes.

ROM is usually only a few thousand bytes of personal computer data

Different types of RAM and ROM

Random Access Memory (RAM) is classified into two types. They are

  • DRAM (Dynamic Random Access Memory) – DRAM Is commonly used as the main memory for the computer. Inside an integrated circuit, each DRAM memory cell consists of a transistor and a capacitor, and a data bit is stored in the capacitor. Because transistors often leak a small amount, the condensers gradually discharge, allowing the information stored in it to drain thus, DRAM has to be refreshed every few milliseconds (given a new electronic charge) to maintain data.
  • SRAM (Static Random Access Memory) – SRAM is composed of 4 to 6 transistors. It holds data in the memory as long as power is supplied to the device, unlike DRAM, which needs to be regularly refreshed. As such, SRAM is more costly but quicker, making DRAM the more widespread memory in computer systems.

Read-Only Memory has three types in it. They are:-

  • PROM–PROM or programmable ROM is a computer memory chip that can be programmed once it is created. When the PROM is programmed, the written information is permanent and cannot be removed or erased.
  • EPROM–Erasable Programmable Read-Only Memory, EPROM is a non-volatile memory chip, developed in 1971 by Dov Frohman. When exposed to ultraviolet light, an EPROM can be reprogrammed if necessary, but otherwise, no new data would be accepted or saved. Computer manufacturers use EPROM when it might be necessary to modify the data stored on the EPROM. EPROM chips are not commonly used in computers and have been replaced by EEPROM chips.
  • EEPROM–The EEPROM is an electrically erasable programmable read-only memory which can be erased and reprogrammed using an electrical charge. George Perlegos developed EEPROM while at Intel in 1978, and unlike most of the memory inside a computer, this memory remembers data when the power is switched off. EEPROM was a substitute for the PROM and EPROM chips and is used for the BIOS of later computers designed after 1994. Using an EEPROM machine helps a computer user to update the BIOS on their device without the need to open the computer or remove chips.

Advantages of RAM and ROM

Some of the advantages of RAM are –

  • It increases the computer system speed, and the higher the system speed, the greater the RAM.
  • The CPU can read data quicker than the RAM. (Compared to hard disk, CD, DVD, FLOPPY, DISK, and USB)
  • There is very little use for battery life.
  • It can write and delete operations.

Some of the advantages of ROM are:-

  • It is non-volatile and is cheaper than RAM
  • As they are static they do not need refreshing every time.
  • Circuits are simple and ROM is more reliable than RAM.
  • Data can be stored permanently
  • It helps to start the computer and loads the OS.

Disadvantages of RAM and ROM

Some of the disadvantages of RAM are –

  • If the CPU wants to read the data from the RAM, then the data access from the registers and the cache is slow in comparison
  • RAM is volatile, i.e. it is difficult to store data forever.
  • It is expensive.
  • It has limited space.

Some of the disadvantages of ROM are:-

  • ROM is read-only, and cannot be modified.
  • If changes are required, it is not possible.

Which is the fastest memory?

RAM is a high-speed memory, with read-write operations happening at a fast rate, whereas ROM is slower-speed memory, which is less susceptible to alteration and can be done via an external program.

The Capacity of RAM and ROM

A ROM chip stores multiple MB (megabytes) of data, typically 4 to 8 MB per chip, whereas a RAM chip can store multiple GB (gigabyte) of data, ranging from 1 to 256 GB per chip.


In this article about RAM and ROM, we saw both of these have their own set of pros and cons.

Yet for a computer system to operate efficiently, all types of computer memory devices are mandatory.

ROM is inexpensive, and can keep data on a permanent basis, but it has its own set of drawbacks such as hard to change the data for a fixed period of time.

RAM is costly but data can be altered several times on it at the same time.

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