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Difference Between RAM and ROM Memory

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RAM is known as random access memory, and ROM stands for read-only memory. These two devices are in-built features that come with your computer, and without them saving information on your computer is pretty much impossible.

The main difference between RAM and ROM is that RAM stores information only when the computer is turned on, while ROM saves information permanently even when a user turns off or restarts the computer.

In a nutshell, data stored on RAM is volatile, while data stored on ROM is permanent. 

What is RAM? 

RAM is a computer's short-term memory. Aside from the computer system, other devices that use RAM includes tablet and smartphones. RAM is quite different from other storage devices in the computer because the data stored on it are volatile. In addition, it keeps information electronically on transistors compared to Hard Disk Drive (HDD) and Solid-State Drive (SSD). 

RAM memory

So, with the RAM, a computer system can access information faster, switch programs, and efficiently run different applications. However, the storage capacity of RAM is active only when the computer is on, and the RAM stops functioning when the computer system shuts down or restarts.

In recent times, computer manufacturers have been creating more than one RAM, so users now have the option of using more than one RAM to enhance their computer performance. Now, let's dive into different types of RAM.


DRAM, fully known as Dynamic Access Memory, is a type of RAM that combines capacitors and transistors to store data. Although DRAM is less expensive, it is slower when compared to other types of RAM like SRAM. Therefore, it is suitable for computer systems whose memory can be replaced or upgraded.


SRAM, fully known as Static Random Access Memory, is a type of RAM that stores data using a six transistor memory cell. This type of RAM is faster and makes the computer system run programs faster. However, SRAM is not replaceable and is generally used as a cache memory for computer processors.

What is ROM? 

ROM is non-volatile storage because it stores information permanently on the chip. Unlike RAM, ROM does not store information using electric current waves. Instead, it saves information by keeping them in individual cells using binary code. As a result, any information stored on ROM cannot be erased even when the computer shuts down or restarts. 


On mobile devices and smartphones, ROM is the main internal storage capacity, and it contains the primary instruction of what needs to happen when the smartphone system is on. ROM is technically known as an embedded multimedia card (eMMC), and it is attached permanently to their circuit board, which means users cannot replace it. 

ROM has three major types, namely which are listed below: 


Programmable Read Only Memory is a blank version of ROM. A PROM can be modified once by a computer using a special tool known as a programmer. Inside the PROM chips, there are miniature fuses that can be burnt open during the programming stage. PROM chips are designed only to be programmed once, so any data saved on them is permanent. 


Unlike Programmable Read Only Memory, Erasable Programmable Read Only Memory can be modified/rewritten severally. However, to erase previous information on EPROM, ultraviolet rays will be applied to the chip. EPROM chips are designed with a quartz window. So, to erase existing data, the user will have to use ultraviolet light, which will be set a specific frequency to burn existing data from the EPROM chip before another program is reloaded on it. 

In addition, EPROM usually has a low lifespan which means it can wear out over a short period. 


Electrically Erasable Programmable Read Only Memory is the most advanced and sophisticated of all the ROM types. Unlike EPROM, erasing existing data on EEPROM ROM does not need special tools like the ultraviolet light used to erase previous data. Furthermore, this ROM type allows the programmer to rewrite the program on the ROM without limit. To remodify EEPROM, the programmer does not need to disassemble the ROM from the main system before erasing existing data.

Differences Between RAM and ROM

Data retention

One major difference between RAM and ROM is how they store data. RAM can only store data when the computer or mobile device is powered. So, when the computer system is off, RAM's ability to store data is deactivated, which means RAM cannot store information when the computer system shuts down. However, ROM is non-volatile primary storage, so data stored on it are well preserved even when the computer system is turned off or restarts.

Physical appearance 

RAM and ROM can be found on the computer system motherboard. However, when it comes to size, RAM is more extensive in length and width than ROM

Storage capacity 

When it comes to storage capacity, RAM has an upper edge compared to ROM. While it is easy to see computer systems having RAM with capacity ranging from 500megabyte up to 32gigabytes, the best storage you can get from ROM is 8megabytes. 

Flexibility in writing data

Since data saved on RAM is volatile, then it can be easily modified. But ROM is non-volatile, making it impossible to rewrite data on the chip with existing data with the exception of EPROM and EEPROM.


RAM is way better than ROM when it comes to speed. RAM can easily access data, and enhance computer performance, making it easy to run different computer programs simultaneously. Also, RAM reads speed in GBs/second compared to ROM MBs/second. 

RAM and ROM Differences on Mobile 

Since mobile phones don't have a hard disk drive like computer systems, they use ROM as their primary storage. On a smartphone, ROM is used to store information like media, files, and games. ROM storage capacity on mobile phones comes in different sizes, and some can be as high as 250GB and even more. 

RAM is also present in mobile phones and tablets. It carries out the same function as what is obtainable in a computer system. While information (games, files, media) is stored in ROM, RAM is responsible for running the program when the device is on. So, the program running is powered by RAM, and the data will be saved on ROM when the program is closed or the mobile device is switched off. 

While it is possible to increase RAM size in computers and laptops, RAM on smartphones can't be changed because it is permanently built with the device. However, the internal storage can be enhanced through the use of an external SD card.

Comparison Chart: Difference Between RAM and ROM

Volatility Data stored on RAM is volatileData on ROM is permanent even when the computer system shuts down. Hence, it is non-volatile
Storage capacity RAM has high storage capacity. For example, some computer systems have a storage capacity of up to 32Gb. 
Mobile (smartphone and tablet) have RAM storage up to 16GB except for iPhones. 
ROM has a lower storage capacity which ranges from 4GB – 8GB. 
Physical sizeBigger Smaller 
Read speed RAM can process data within GBs per second. The processing speed of ROM is MBs/seconds, which makes it slower when processing data. 
Rewrite Existing data on RAM can be easily modifiedExisting data can be easily rewritten on EPROM and EEPROM. 

Similarities Between RAM and ROM 

Accessing memory 

Although RAM and ROM retain information differently, their main similarities are that they are both primary memory storage in the computer system.

Binary form 

Both RAM and ROM represent data stored in them using series of binary digits, also known as bits. 

Holds information

Random Access Memory and Read-Only Memory are primary storage devices that can store information in program instructions for the same specific types of data. This data can be passed directly to the computer system central processing units (CPU), input and output controllers, and circuitry of the processor. 

Frequently Asked Questions

💻 Can the computer system function without RAM and ROM?

Though the computer system has different storage options, divided into primary and secondary memory, the computer primarily needs RAM and ROM, which are categorized as primary memory to boot and operate efficiently. 

🛌 Can RAM operate when the computer is off?

Unlike ROM, which is non-volatile, RAM can only function when the computer system or mobile phone is powered on.

📱What is the difference between computer RAM and mobile phone RAM?

RAM is upgradable in a computer system, but in mobile phones, it can't be upgraded. 


Knowing the difference between RAM and ROM is necessary, especially in a world where we are exposed to many gadgets. So this is a great place to get started on brushing up your computer knowledge.


Feel free to comment and discuss about the article in the comment space below if you have any information or remarks to add. If you think we made a mistake, you can also report it there.
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About the Author: Nicolas Seignette

Nicolas Seignette, who holds a scientific baccalaureate, began his studies in mathematics and computer science applied to human and social sciences (MIASHS). He then continued his university studies with a DEUST WMI (Webmaster and Internet professions) at the University of Limoges before finishing his course with a professional license specialized in the IT professions. On 10Differences, he is in charge of the research and the writing of the articles concerning technology, sciences and mathematics.
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