5 Different Types of ROM

Different Types of ROM
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There are different types of read-only memory or ROM. Each type has its own set of characteristics that make it unique.

Read-only memory (ROM) is a storage medium that stores data permanently and cannot be modified. 

There are many different types of ROM, each with its own set of characteristics. The most common type of ROM is flash memory, which is used in everything from digital cameras to USB drives.

Other types of ROM include EEPROM, PROM, and EPROM. They all have the same characteristics as flash memory: they can’t be written after they’re manufactured.

One difference between these types of ROM and flash memory is that the other three need a special device for writing information into them, whereas flash memory doesn’t require this step. 

In some cases, it’s possible to use specialized software or hardware devices like an EEPROM programmer to write new information into them if necessary.

In this blog post, we’ll explore 5 different types of ROM and their key characteristics. By the end, you’ll better understand which type of ROM best suits your needs.

1. Masked Read-Only Memory (MROM)

MROM is a type of read-only memory that is programmed using a mask during the manufacturing process.

It is non-volatile, meaning it retains its contents even when power is removed. MROM is fast and has a low access time, making it ideal for use in devices that require quick execution, such as embedded systems. 

One downside to MROM is that it is not reprogrammable, so once it has been programmed, it cannot change its contents.

Another limitation is that it requires more voltage than other types of ROM, which can make it less efficient if used with a battery.

However, because MROM does not need to be refreshed like other types of RAM, devices containing this type of memory can operate without needing external power sources.

2. Programmable Read-Only Memory (PROM)

PROM is one of the different types of ROM that can program to store data permanently. It makes it ideal for storing information that doesn’t need to be changed often, such as the BIOS in a computer. 

PROM chips are one-time programmable, which can only be programmed once. After that, they are locked and can’t be changed. It’s also called One Time Programmable (OTP) or One Time Write (OTW). 

These types of chips can store up to two million bits. The Basic Input Output System or BIOS is a special PROM chip located on the motherboard of personal computers.

Some people refer to this type of chip as write-protected because you have to use specialized software and hardware tools to write new data onto the chip after it has been programmed.

3. Erasable and Programmable Read-Only Memory (EPROM)

EPROM is one of the different types of ROM that can be erased and programmed electrically. It is made of an array of floating-gate transistors. EPROMs store data that needs to be updated frequently or in large quantities. 

They are also used to store programs that need to be run on a computer. When the program has been edited, it has to be reprogramed into the machine’s main memory before the program can execute. 

Flash Memory is the most common technology used for this purpose, which can be read and written quickly by any system with an appropriate controller chip.

There are many different types of ROM (Erasable Programmable Read-Only Memory), but these two should be the ones you use most often.

4. EEPROM (Electrically Erasable and Programmable Read-Only Memory) 

EEPROM is among the different types of ROM that can be erased and rewritten electrically. It is useful for storing data that needs to be changed frequently. EEPROM is slower than other types of ROM and has a limited number of write cycles. 

The contents are not erasable by exposure to light, so you cannot use them for CDs, DVDs, and Blu-ray discs.

There are two types of flash memory: NOR (Not OR) and NAND (Not AND). NOR chips are more expensive but faster, while NAND chips offer higher storage density.

5. Flash memory

Flash memory is a type of EEPROM, which stands for electrically erasable programmable read-only memory.

Flash memory can be erased and reprogrammed in blocks instead of one byte at a time like traditional EEPROM. It makes flash memory faster than EEPROM when it comes to writing data. 

Flash memory is used in USB flash drives, digital cameras, and solid-state drives (SSDs). One disadvantage of flash memory is that the maximum amount of erase cycles varies depending on size.

It’s estimated that chips will last 100,000 erase cycles while cheaper ones will only last 10,000. 

Among the different types of ROM, there are two types of Flash Memory: NOR and NAND. In the world of RAM, there is SRAM, DRAM, and SDRAM.

In the world of ROM, there are two types: NOR and NAND. The difference between these memory relies on how they store information internally. 

NOR (which stands for not OR) memory uses transistors to store bits in rows that go from 0 up to 1 (the first row has 0’s and 1’s going down vertically) with all cells connected by pass transistors so that you can access an entire row by applying a single high voltage signal across an individual cell in any column.

To use a specific row from NOR memory, you would apply a high voltage signal across the row containing your desired bit before reading or writing it as needed.


There are many different types of ROM, each with its advantages and disadvantages. The type of ROM you choose should be based on your specific needs and requirements.

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