RAM vs. ROM – What Is the Difference?

Despite their apparent similarities, random-access memory (RAM) and read-only memory (ROM) serve very different purposes.

Nikolina Cveticanin Image
Updated:

October 18,2022

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Despite their apparent similarities, random-access memory (RAM) and read-only memory (ROM) serve very different purposes.

Would you rather have a Ferrari with no engine or an engine without a car? It's a silly question, of course, because you need both the car and the engine to make it go. The same is true for your computer – you need both RAM and ROM to make it work properly. So, let’s take a look at how these two important computer components differ.

RAM vs. ROM

In the tech world, there are plenty of acronyms and technical terms that can be confusing. RAM and ROM are among these terms. A lot of people don't know the difference or use the terms interchangeably. But they are actually two very different things.

RAM stands for random access memory. This is where your computer stores the active data that is being processed at any given time. So, while you are working on a document, the most up-to-date version is only in RAM until you save it. If you turn off your PC or close the program, the file is gone forever. 

ROM stands for read-only memory. This type of memory comes preloaded with the necessary information to start your PC. The data is stored permanently, which means it cannot be deleted like data stored in RAM, but it can be modified in some cases. Information stored on ROM will remain saved no matter what you do on the PC. So, when your computer starts up, it will load from ROM into RAM so that you can use your computer. 

Because both memories can be accessed directly by the CPU, they are classified as primary memory. On the other hand, devices used for permanent storage, such as HDD and SSD, are classified as secondary memory. 

What Is RAM?

As already mentioned, RAM is incapable of permanently storing any type of data. Such memory is called volatile memory because the data is stored only until the power is turned off or the CPU discards it based on user input. After that, all the information stored in random access memory will be gone.

While this may sound like a drawback, there are some upsides to having a volatile memory. For starters, it can store data much faster than non-volatile memory. When running programs, this is crucial because your CPU relies on high-speed memory to access data quickly so it can process it.

If the data were stored on a slower type of memory, the CPU would have to wait longer to get the data it needed, which would make your computer run slowly. 

Another advantage of RAM is that the CPU can write data to it and delete it as many times as needed. This makes it ideal for storing data that is constantly being changed, like the data in your active programs. Speed and the way the access data is stored are the biggest differences between RAM and ROM.

Types of RAM

There are two main types of RAM

  1. Dynamic random access memory (DRAM) - This is the most common type of RAM chip. It stores data in transistors and capacitors that are charged with electricity. When the power is turned off, the charge is dissipated, and the data is lost. The dynamic RAM needs to be refreshed constantly or data will be lost. Dynamic RAM is further subdivided into Synchronous DRAM (SDRAM), Rambus DRAM (RDRAM), and Double Data Rate SDRAM (DDR SDRAM), but that is a separate topic. 
  2. Static random access memory (SRAM) - This type of RAM chip uses bistable circuitry to store data in memory cells. Static RAM doesn't need to be refreshed like DRAM, so it's faster. It's also more expensive and is used mostly as CPU cache memory.

While there are some fundamental variations in how they store data, the most significant RAM difference is in speed. Still, both types of RAM can lose data if the power is cut off, so it's important to save your work often. 

How Much RAM Do I Need?

The amount of RAM you need varies depending on what you use your computer for. If you only use your computer for basic tasks like browsing the internet or checking email, you can get by with 8 GB of RAM. However, if you engage in demanding tasks like video editing or gaming, you'll need 16 GB of RAM or more. 

Some computers come with 32 GB of RAM, but that's overkill for most users. Having extra unused RAM won’t further improve your PC's performance. 

What Is ROM?

ROM is a non-volatile memory type, meaning that the data stored in it will not be deleted when the power is turned off. This is because ROM is designed to hold data that doesn't need to be changed and that will be used every time you turn on your computer. Without it, you wouldn’t be able to start your PC. After all, the CPU is just a piece of silicon that needs to be instructed as to what it should do once it gets power. 

The best-known use of ROM is to hold BIOS firmware, which stands for Basic Input/Output System. It's a small piece of software that starts up your computer and loads the operating system before it hands full control to it. 

Nowadays, the BIOS is stored on flash memory in the majority of PCs, which increases the risk of the BIOS being infected with malware. This simply isn’t possible when the BIOS is located in ROM. 

Since the BIOS has been moved to flash memory, what’s the ROM function now? The ROM stores firmware for other electronic devices your PC needs to start when booting up. You can think of ROM as the boot-up instructions for your PC, while RAM is the silent workhorse. While there are obvious differences between RAM and ROM, they can’t work without each other. 

Types of ROM 

There are four main types of ROM

  1. Mask ROM - This is a type of read-only memory programmed by the manufacturer that cannot be changed by users. Once the data is written to the mask ROM, it can only be read, not erased or modified.
  2. Erasable Programmable Read-Only Memory (EPROM) - Read-only memory that can be erased and programmed by users. To erase data from an EPROM, you need to use ultraviolet (UV) light at a specific frequency.
  3. Programmable Read-Only Memory (PROM) - Read-only memory that can be programmed by users but not erased. Once the data is written to a PROM chip, it can only be read, not modified or deleted.
  4. Electrically Erasable Programmable Read-Only Memory (EEPROM) - Memory that can be programmed and erased multiple times with the help of an electrical charge. Computers use EEPROM to store small amounts of data, like the system configuration settings.

How Much ROM Do I Need?

You don't need to worry about the amount of ROM on your computer, as it is not something that can be upgraded. The amount of ROM on a computer is determined by the manufacturer and is based on the needs of the operating system and other installed software.

What's the Difference Between RAM and ROM? 

Both types of memory store data, but that's where the similarities end. RAM is volatile, meaning that anything stored in it disappears when the power is turned off. ROM, on the other hand, is non-volatile; data stored in it remains intact even when the power is shut off. This is your most basic, bare-bones definition of the difference between RAM and ROM, but there are finer points to underscore as well. 

  • Data Retention: RAM is designed to keep data only temporarily, while ROM is designed to store it permanently.
  • Access Time: RAM can be accessed much faster and at any time, while ROM is slower and only accessed during the device startup process.
  • Capacity: RAM's storage capacity is significantly greater than ROM's.
  • Ease of writing: It is easy to write data to RAM, but it is much more difficult to write data to a ROM chip, if at all. 
  • Appearance: RAM chips have separate slots and can be taken out without issue. On the other hand, computer ROM chips look like any other embedded chip on the motherboard, and you shouldn’t try to take them out on your own. 

Conclusion

All in all, ROM and RAM are quite different types of computer memory with different functions. They only have one thing in common: They both represent a memory aspect of the computer system that is required for normal computer system operations. But beyond that, they are rather distinctive. 

RAM is made to hold data temporarily and is much faster and more versatile than ROM memory. Contrarily, ROM data contains critical boot-up information needed to start a computer system and does not need to be fast or alterable.

FAQ
What are the five differences between RAM and ROM?
  1. RAM is faster than ROM.
  2. RAM is volatile memory, while ROM is non-volatile memory.
  3. RAM can be readily written to, but ROM, in most situations, cannot.
  4. RAM needs power to retain data, while ROM does not.
  5. ROM is active when the computer is switched on, while RAM is not.
Why is ROM so important?

ROM is important because it stores the computer's BIOS and other firmware needed to start the PC in the first place. The BIOS contains all the necessary instructions for the computer to start up and function properly. Without ROM, the computer would not be able to boot up or function properly.

Which is better, RAM or ROM?

While there are RAM vs. ROM comparisons, they are made just for the sake of explaining what each of them does. The fact remains that you need both. There isn’t an option where you can pick one because it’s better: You won’t be able to turn on your machine without ROM, and it won’t be able to do anything without RAM.

 

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