What is ROM and how many types of ROM.

What is ROM and how many types of ROM.

(In this post we will read in detail about types of ROM (types of ROM), in this we will read prom, eprom, eeprom in easy language.)


what is ROM (What is ROM?)

The full name of ROM is read only memory (read only memory).  It is a non volatile memory.  It is a means of storing data in computers and other electronic devices which is a means of storing data permanently.

The difference between RAM and ROM is that


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

types of ROM ROM types are of the following three types:

What is ROM and how many types of ROM.


  1.  PROM
  2.  EPROM
  3.  EEPROM

what is PROM?

what is PROM?

The full name of PROM is programmable ROM (programmable read only memory).  It is a memory chip that can be programmed only once.

It is also called OTP (one time programmable) chip, once the PROM is programmed then the data cannot be erase from it.  That data forever gets written to that chip.

PROM was developed in 1956 by Wen tsing chow.  When the computer is turned off, the PROM keeps containing its data.  The difference between PROM and ROM is that PROM is empty when it is created, while ROM is programmed only when it is created.

The PROM chip requires a device to program or write data, which we call PROM programmer or PROM burner.  And the process of writing this chip is called PROM burning.

Nowadays PROM is not used.  It has been replaced by EEPROM.

what is EPROM?

What is EPROM?

The full name of EPROM is erasable programmable ROM (erasable programmable read only memory).  EPROM is a non volatile memory chip invented in 1971 by Dov frohman.  Even when there is no power supply, it keeps containing the data.

The data in EPROM can be erase and can be rewritten.  Data is erase from the memory chip by ultraviolet light so that we can write or program it again.

In order to erase data from the FPROM and to program it, we need a special device which we call PROM programmer or PROM burner, and the process of programming in EPROM is called burning.  Programmed EPROM can retain data for 10 to 20 years.  Above the EPROM is a quartz crystal window through which ultraviolet light erase the data.

Repeatedly erasing EPROM's data destroys its silicon dioxide layer, making it unreliable.  Therefore it is harmful to erase EPROM again and again.

EPROM was used in place of PROM.  But in today's computers, EPROM is also not used, instead EEPROM (electrically erasable programmable read only memory) is used.

Advantage of EPROM:

  Its benefits are as follows:

  •  It is very cheap.
  •  It can be programmed again,
  • When the power supply is not there, it retains the data.
  •  Testing and debugging can be done in it.

 disadvantage of EPROM:

 Its disadvantages are as follows.


  • EP - The resistance of the transistor used in ROM is very high.
  • It consumes more power.
  • It requires ultraviolet light to erase the data and it cannot be erase from electrical signal.
  • Like EEPROM, no particular byte can be erase ie all the data in it gets erase.
  • To erase data in EPROM and re-program it has to be removed from the computer.
  • Programming in this is very slow.
  • It has a higher price than PROM.


what is EEPROM?

what is EEPROM?

The full name of EEPROM is the electrically erasable programmable ROM (electrically erasable programmable read only memory), developed by George perlegos at Intel in 1978.  It is a non volatile memory chip that is used to store small amounts of data in a computer.

Data bytes in EEPROM can be erase and reprogram.  In this, the data byte is erase by electric charge, so that it can be re-programmed.

EEPROM STUH PROM (programmable read only memory) is done in place of a4T EPROM (erasable programmable read only memory).

In order to erase the EPROM chip it has to be removed from the computer but the EEPROM does not need to be removed from the computer, the EEPROM is like flash memory (flash memory) but the inequality is that EEPROM only has one time  Only one data byte is erase or write whereas in flash memory the data blocks contain erase or write.  Because of which flash memory is faster than EEPROM.


types of EEPROM EEP :

There are two types of ROMs:

  1.  serial EEPROM
  2.  parallel EEPROM 

serial EEPROM: - It consists of data transfer serial (serialized) and its procedure is very complex.  It is slower than parallel due to being a serial data transfer.

parallel EEPROM: - parallel EEPROM & serial EEPROM az is also reliable and can be used with EPROM and flash memory, but due to their high value, they are rarely used.

The advantage of EEPROM EEP ROM is the following. 


  • In this, data is erase by electrical method which is faster method.
  •  In this we can erase the entire data.  And data to a byte as well.
  • To erase the data it does not have to be removed from the computer.
  • It is very easy to program.
  • EEP-ROM can be reprogram countless times.

Disadvantages of EEPROM are its disadvantages:


  • EEPROM is more expensive than prom and eprom.
  • In this, different voltages are required to read, write, and erase the data.
  • This data can only be retained for about 10 years.

Request: - How did you like this post of types of ROM (type of ROM) and tell me by comment and share it with your friends.  Thank you .
Satish jagtap

Hello iam Satish jagtap Electrical engineer. From: Aurangabad, Maharashtra. Edu: MIT college of Engineering.

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