What is ROM / Types Of ROM Full explanation with Example

What is ROM and Types of ROM

A computer has two types of memory which are primary and secondary. two types of primary memory One is RAM and Second is ROM

Whenever you buy a mobile or laptop, you definitely ask the shopkeeper how many GB RAM is there in it. Nowadays you get to hear a lot about RAM and ROM and in more tar you see more RAM and ROM name in the specifications of the phone.


The full name of the ROM is " Read Only Memory ". It is an important part of the computer out of the parts connected to the computer. 

Friends, as we all know that our computer or mobile has 2 types of memory known as RAM and ROM. ROM is also called permanent storage because it contains a data store.

What happens is that when we turn on our mobile or computer, RAM starts working and when we power off the computer or mobile, all the data gets stored in ROM. 

We can also add external ROM such as chip in mobile, pen drive in computer, hard drive etc. are also ROM.

What is ROM?

For example, when we go to purchase a mobile or computer, then we check its internal memory

It happens that internal memory is 32 GB but it looks like 28 or 29 GB which is a little difference between them. That is called ROM.

So as its full name is read only memory, we can only read it because there is a fixed program in it, which we cannot do anything nor can change it. 

This is the in-built memory of the computer whose data is read only and nothing can be written and modified.

The ROM is one of the parts connected to the computer. It is a core part of the computer. It is a primary storage device. It is chip-shaped and attaches to the motherboard. 

It boots up the computer and when you turn on the computer for the second time, it gives new life to your data.


The full name of RAM is Random Access Memory. It is the most important part for any computer or device. 

RAM is used to store data but it stays stored as long as it keeps power on. When the power goes off, the store data in it goes out like - Suppose your phone is switched off.

Right now your ram is completely empty and your RAM is not being used. All the applications are in your phone storage or in your memory card. 

As soon as you start your phone, your operating system will be loaded in your phone.

This system will first use your RAM and along with it all applications will start with the help of RAM. 

This is the reason why your phone's RAM continues to be used even after closing all applications. 

After this, when you open a new application on your mobile, it goes into RAM and after opening a few applications it becomes full.

After RAM is full, if you open an application, then it closes the old app to replace it. Turning off means that it removes that application from its RAM and sends it to internal storage. 

Due to repeated process, the speed of our phone decreases, so the larger the RAM, the higher the mobile speed.

ROM Functions:

The full form of ROM is Read Only Memory. ROM is Memory where we save all our data like - audio, video, photo, document and the software or apps installed is also saved in ROM. 

RAM is faster and speedy then ROM. There is a huge difference in the price of ROM and RAM, mainly because the speed of RAM is high and the cost of making is high.

What is ROM?

RAM Functions:

The full form of RAM is Random Access Memory. Data in RAM is saved only as long as the power supply remains in it, but your data gets deleted as soon as its power is off. 

RAM is a temporary memory. When we start a software or an app, it works on our RAM but it is saved in the ROM until it starts.


RAM required:

By the time the software starts and works, RAM is needed because our computer wants the software to work faster and the ROM speed is very low and the RAM speed is very high. 

So our computer starts the software or app on RAM so that the software works quickly and as long as our software works, RAM is used as soon as you stop the program then it gets deleted from your RAM. But ROM remains saved.


Difference between ROM and RAM:

The main difference in ROM OR RAM is that when you shut down your computer, RAM loses its data but ROM does not require any continuous power to do its work. 

ROMs can store their information even after the computer is turned off. Using the ROM chip helps the computer to get started.

The ROM chip works slowly. The ROM chip can store only a few megabytes of data and is also used in some gaming system cartidges. 

ROM is non-volatile memory while RAM is volatile. Data can be stored permanently in ROM while in RAM it cannot be stored permanently.


Types Of ROM:

There are 4 types of ROM which are as follows-




This is a ROM that we can change once we update and then we can never update or change it. 

What happens is that there are some small fuses in which Instruction is inserted through programming, then once programmed it cannot be re-erase again.

It is like a digital memory IC and is used in CRT monitors. It is a permanent time program and the data stored in it is also permanent. Most of this happens in an electric device.



This ROM was used a lot before but now no one uses it, it is read only memory hard wired devices from which pre-programmed data and instruction is stored. 

At that time these types of memory were very expensive but in today's time they are not found anywhere.



It is a chip that stores computer data after the computer is turned off. It is used by P.C.O. The computer is made in TV Tunar. 

In this, data is inserted and erased with the help of laser. The special thing about this ROM is that we can also erase it easily and can also program it.

What is ROM?

But the way to erase this memory is quite different in that this memory is empty when this memory is passed to Ultra Violet light for about 40 minutes. "EPROM Eraser" is also used to achieve this work.

When programming, a charge is inserted inside it which is kept for more than ten years because there is no way for the charge to exit so it stays inside that memory. 

Ultra Violet Light is passed through the Quartz Crystal Window to erase this charge. All the charge becomes Erase only with the effect of this light.


Benefits of EPROM:

It is very cheap. It can be reprogrammed. It retains data even when power is not supplied. Testing and debugging can be done in this.


Disadvantages of EPROM:

The transistor used in EPROM has a very high resistance. It consumes more power. It requires ultraviolet light to erase data and cannot be erased with electrical signals. 

It cannot erase a particular byte like EEPROM means that all data is erased in it. To erase data in EPROM and re-program it has to be removed from the computer. 

Programming in this is very slow. It costs more than PROM.



Whenever there was a change in technology, the ROM also needed to change because of this the same memory was used because with this we can erase 10,000 times and can also be programmed. 

In this, some size data is stored after the computer is turned off. It attaches to the motherboard of the computer. Its job is to turn on the computer.

This tube acts as a lighter starter. In this, you can read any data, erase it or you can write it again, but for this you have to give signal by byte (BYTE). Nowadays some different type of EEPROM is also used to store a slightly larger size of data in ROM. It has a limited time.


Types of EEPROM:

There are two types of EEPROM - Serial EEPROM and Parallel EEPROM etc.


1. Serial EEPROM: 

It involves data transfer sort and its procedure is very complex. It is slower than parallel due to serial data transfer.


2. Parallel EEPROM: 

Parallel EEPROM is one that is faster than Serial EEPROM and also reliable and can be used with EPROM and flash memory. But due to their high value, they are rarely used.


Advantages of EEPROM:

In this, data is erased by electrical method which is fast method. In this we can erase the entire data and the data even by one byte.  

It is very easy to program. The EEPROM can be reprogrammed countless times.


Disadvantages of EEPROM:

EEPROM is more expensive than PROM and EPROM. The EEPROM requires different voltages to read, write and erase data.



It looks like a semi-conductor in which you can make the changes you want by giving some electric signal. This together with RAM helps to turn on the computer and bring the display. It also looks similar to an IC.

Also Read : What is kernel in computer and it's importance ?



It is like a microprocessor which together with ROM helps to turn on the computer system. It also controls the flow of data between computer connected devices such as a mouse, keyboard, hard disk and video adapter, and between computer operators.


ROM Benifits:

1. ROM is much cheaper than RAM.
2. Data of ROM does not change automatically but only when we make some changes in it.
3. It is of Non-Volalite nature which maintains the program permanently.
4. It does not need to be refreshed.
5. It is more reliable than RAM because data remains in RAM as long as the power supply is there.
6. It is very thoughtfully put into it, which we cannot change again and again.

Also Read : What is  Network Hub - Definition and full Information

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