What is ROM? Know Everything About Read-Only Memory


We all use mobile phones and computers, but do you know what RAM or ROM is? If not but want to know, then this post is going to be helpful for you. Because today in this post, we will know what is ROM? And also about its type, benefits, and work? Everything about ROM.

If you are a computer user then you must have heard about ROM because it is an important part of any computer. But do you know what exactly it is? And what is its function on your computer?

If you still do not know about Rom, then it is fine because after reading this article, you will get a lot of information about it.

what is rom

Guys, it is important to know here that it is used not only in computers but also in mobile, washing machines, TV, and AC, etc. Therefore, you can understand that in the present time ROM is being used in many devices. So if you know the importance of technical knowledge, then you must know about ROM.

If you want to get complete information about Rom, then this article is for you. So read this article carefully, in this we will know almost everything about the Read-Only Memory.

In the previous post, I told you what is a Computer? And its types and today in this post, we will know what is ROM?

What is ROM (Read Only Memory)?

ROM means Read Only Memory, it is a type of storage medium whose function is to save data permanently in computers and other electronic devices. It starts working when the computer is turned on because the ROM has programming to start the PC, which causes a computer to boot-up. It acts on the instruction of a software/program by the user in the computer and performs the major input/output tasks.

However, It is important to understand here that usually Rom works only to read, not to write data. Despite the power off/shut down of the computer, data save in ROM remains. While the data stored in Ram disappears after power off on the other side.

how it looks

Also, it is important to know that there are many chips on the motherboard, some of which are located in the expansion board. These chips are required in the basic input/output system (bios), boot up, read and write devices, etc.

Rom is a type of non-volatile memory. Non-volatile memory is the memory that works to save store data in the device even after it is cut off. On the other hand, to store data in volatile memory, you must be constantly on power.

read only memory

Since ROM cannot be changed, it can only be read. It is mainly used for the firmware. Firmware means a set of software and instructions that are affixed to attached to a hardware device.

The firmware fulfills all the instructions about how a device communicates with various hardware components. Firmware is considered permanent because it does not change until it is updated.

Other Types Of Non-Volatile Memory

  • Programmable Read-Only Memory (PROM)
  • Electrically Programmable Read-Only Memory (EPROM)
  • Electrically Erasable Programmable Read-Only Memory (EEPROM; also called Flash ROM)
  • Electrically Alterable Read-Only Memory (EAROM)
  • ROM is often also included in optical storage media devices such as compact discs that read-only memory (CD-ROM), compact disk recordable (CD-R), and compact disk rewritable (Cd-Raw), etc.

How Does ROM Work?

Read-only memory is an integrated circuit chip that is already programmed with various functions. It is also called firmware. The ROM chip operates like an array, the ROM chips have a grid of rows and columns to turn on/off.

When the value is one, it uses a diode to connect the lines, but if the value is 0, it means that the lines are not connected. Each element of the array matches the storage element of the memory.

Depending on the methods used to write data to the ROM chip and the number of times they are written, the ROM is divided into different parts.

Types of ROM

There are mainly two basic components of ROM, the first Decoder and OR gates and the functioning of these components also varies. The input of the decoder is in binary form and the output corresponds to decimal. And all the OR gates in Rom take the output of Decoder as input.

  • Mask Read-Only Memory (MROM)
  • Programmable Read-Only Memory (PROM)
  • Erasable Programmable Read-Only Memory (EPROM)
  • Electrically Erasable Programmable Read-Only Memory (EEPROM)
  • Flash Read-Only Memory (Flash ROM)
types of rom


MROM means Mask read-only memory It is manufactured (manufactured) with chip contents. These ROMs are inexpensive and used in hard-wired devices that already had a program set of data and instruction.

These chips have a software mascot that burns on the chip during the design phase of the semiconductor manufacturing process.

The main advantage of Mask read-only memory is that its production cost is very low, IC is priced based on size such as per bit when this amount of memory is built, it would be available to customers much cheaper than other secondary memory.

Use of MROM Memory?

In a network operating system to store data sound in electronic musical instruments to store fonts for laser printers.

If we talk about its loss, then its time is very short because if there is an error in the code, then the MROM memory becomes useless, that is, it needs to be replaced for a change in the code, so the design errors are expensive in it.

Advantages of MROM?

  • One advantage of using MROM on any computer is that its production cost is low.
  • Mask ROMs are more compact than other ROMs.
  • MROM costs less than any other secondary memory because its cost is also low, due to which it is available in the market at a cheap price.

Disadvantages of MROM?

  • If an Error Code comes in it using MRom, then in this case, it proves useless because it is difficult to repair and replace Mask Rom (MRom) again.
  • Apart from this, we M Rom does not last much longer than any other RAM and its life expectancy is low, so they have to be changed from time to time.


This memory is blanked as empty, as the name suggests, it is programmed after manufacturing, that is, a user buys blank memory, and puts it in the content according to the PROM programs.

The data in this memory can be programmed only once and cannot be converted later. PROM memory is used in the following tasks; video gaming console, high definition multimedia interfaces (HDMI), Radio-Frequency Identification (RFID) tags, to provide special options to users in mobile phones.

Programming can be done through various software in this memory and memory does not need to rely on the hard wiring of programs.

Data changes cannot be made in this. Therefore, the authority of the data remains intact and there is no scope to change it, so it can also be called reliable.

It cannot be erased when data is burnt in PROM memory and it cannot be changed when an error is detected.

Advantages of PROM?

  • Programming of this ROM can be done through several types of software.
  • Another main advantage of PROM is that once it is programmed, then the information or data contained in it can never be erased or deleted.
  • Because it has information permanent.
  • It is also used in other electronic devices such as computers as well as medical devices.


That is Erasable Programmable Read-Only Memory This is a type of non-volatile memory, ie it saves data even when power is off.

A disadvantage of PROM memory was that once the memory was programmed the data could not be changed but EPROM memory solved the problem.

EPROM memory is used in the following applications. For program development for the bios chip in a computer as a program storage chip in modems, video cards, and many electronic gadgets.

Advantages of EPROM?

  • It is a non-volatile memory.
  • Its other major feature is that it can be erased even after being programmed and can be re-programmed.
  • It is less cost-effective as compared to PROM.
  • It returns to EPROM memory even when the power is not on and it does not require any external memory.
  • Computers that work as Bios.

Disadvantages of EPROM?

  • Although it can be reprogrammed, when it is reprogrammed, it is removed from its board only when it is reprogrammed.
  • This ROM can be Erase as we know it. But friends, no particular BYte can be erased in it, ie information gets destroyed in one turn. So, all your content gets deleted from here.
  • Apart from this, EROM based on UV is available in the market itself, which takes more time to remove the content.
  • The static power consumption is higher in the E Pro as transistors also use higher resistance.


That is Electrically Erasable Programmable Read-Only Memory. It works just like EPROM and it has been developed to overcome the shortcomings of EPROM. It is electronically erased or programmed because it uses electronic signals in place of ultra voice rays.

However, It takes 4 to 10 milliseconds to erase data and do programming. It is also possible to delete only the byte at a time in place of the entire chip. The chip can be erased or reprogrammed approximately 10,000 times. However, this process is slow.

Advantages of EEPROM?

  • EEPROM can be programmed into a computer more than once.
  • As we knew EEPROM could not delete data based on byte but EEPROM is the opposite, here you can delete the contents of the board on a byte basis.
  • It does not require any additional device to change data.
  • EEPROM also exists in computers as a Bios chip and the method of erasing the data in it is electrical and instant so that the information gets deleted faster.

Disadvantages of EEPROM?

  • Different types of voltages are required to read or write erase data.
  • The data retention time of EEPRPOM is limited eg it can be up to 10 years old.
  • EEPROM devices are more expensive than other devices.

Flash Memory

It is a universal flash programming non-volatile memory, which is used as storage in a computer, it can be deleted and re-programmed with the help of electricity.

The memory blocks of data in this chip can be deleted or stored at specific times. Also, Information/notifications in ROM can be easily updated because it is non-volatile memory, which means that the device works to store ROM data in that device even after a shutdown or power cut. ROM chips can be used with computers of different computer brands.

Advantages of Flash Memory?

  • Many of today’s electronic gadgets such as Pendrive Flash Memory are supported.
  • It has a high transfer speed.
  • Data is saved in flash read-only memory in case of computer shut off, shut down. That is, it keeps doing its work even in the absence of power.
  • This is quite a strong memory.

Disadvantages of Flash Memory?

  • Because of the latest technology and better functionality, the price of FROM is high.
  • Apart from this, the other disadvantage is that it has limited read/write numbers.

Features Of ROM

  • Store data in ROM cannot be changed, even if a change is possible, it is very difficult.
  • Data or programs in ROM cannot be coded by one user. It is already installed in it at the time of manufacturing such as firmware.
  • Despite the sudden power off, the data that is in the ROM, we can access the stored data even after the computer is shut down for a long time. Therefore it is considered as non-volatile memory, on the other hand, the data in FROM is not saved after power off.
  • ROM is engaged in computers as bios.
  • One of the main features of ROM is that it provides a large amount of expansive data storage to the computer user compared to ROM.
  • Also, It is cheaper than RAM but both are different.
  • The central processing unit is a part of the CPU. It is installed in the motherboard as a chip.
  • This is a permanent memory, there is no need to refresh the store data again and again.
  • So friends, till now you know about all the features of Rom, now we have learned about both its advantages and disadvantages, one thing and it is also important to know that not only we use Rom on our computer devices. In fact, Rom also has other electronic devices such as refrigerators, washing machine TVs, etc.
  • And according to each device, there is a Rom in it, there are programmable functions in it. Those are added at the time of manufacturing.

Final Words

Hopefully, after reading this article till the end, you must have understood what ROM is? How many types of ROM are there? And what are the features of ROM? I hope you like this information.

If you like this post then share it with your techy friends and also on social media. Also, If you have any questions related to this post, then comment below.


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