RAM vs. ROM: What Is the Difference?

Nikolina Cveticanin

Updated: July 14, 2023

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Ever since computers went mainstream, consumers have been confusing RAM vs. ROM. It’s all just computer memory to the average user, so what are the actual differences between the two?

RAM and ROM are two completely different types of memory, and both play an important role in a computer system. So, to properly examine their differences and similarities, we’ll start from the top, defining each type of memory and taking a look at how they’re used.

What Is RAM?

Starting with the acronym, RAM stands for random access memory. It’s called that because it’s designed to be accessed, read, and written to at any point while the device is working. RAM is, therefore, the primary memory that your computer or smart device works with.

However, RAM is also volatile memory. It doesn’t keep the data stored forever, nor does it hold any data when the power is turned off. 

How does RAM work, then? Whenever you’re accessing any files or apps, the computer stores some of that data in the RAM, like the document you’re working on, for example. This temporary memory is emptied the moment you close the document or shut down your PC.

So, the RAM’s purpose is to provide quick access to all the data that active applications on your computer or smartphone need. For office apps, that could be documents and spreadsheets, alongside any images and fonts. In video games, that’s textures, shaders, and models in the level you’re playing.

That said, a major difference between RAM and ROM is the speed of data access that RAM provides, which is much higher than ROM. In fact, the latest chips are capable of processing over 70 gigabits of data per second. Still, more RAM means more data can be stored at a given time, leading to improved multitasking, and there are certainly some apps that require vast amounts of RAM. 

Types of RAM

There are two distinct RAM types:

1. Dynamic Random Access Memory – When you hear anyone talk about memory modules or memory sticks, it’s DRAM they’re talking about. This type of RAM stores data in cells composed of capacitors and transistors, requiring constant electricity and refreshing to store data. DDR memory is the most common type of DRAM used today.
2. Static Random Access Memory – Often used as CPU cache memory, static RAM is faster and more expensive than DRAM. It also works differently, storing the data in a memory cell made out of six transistors, and it doesn’t need to be refreshed in the same manner as DRAM.

Similar to the general ROM vs. RAM differences, there are certain differences between types of RAM. Still, one thing all RAM types have in common is that none of them can retain data when the power is turned off. This is the main reason why RAM isn’t used for storage, but as operational memory.

How Much RAM Do You Need?

PC software has become increasingly RAM-hungry. Nowadays, 8 GB of RAM is the bare minimum for a Windows 11 desktop PC. If you’re running video games or any of the Adobe Creative Suite apps, then going with 16 GB or even 32 GB of RAM is a must. 

If you’re building a new PC, note that having more than 32 GB of RAM won’t improve your PC’s performance unless you’re running highly demanding professional applications. 

What Is ROM?

Read-only memory, or ROM for short, is almost the complete opposite of RAM. It’s non-volatile memory, meaning that it doesn’t lose data when you turn the computer off, but it also frequently comes with pre-recorded data. Most importantly, it’s usually not possible to modify this type of memory.

ROM is commonly used to store the firmware of various devices, including the PC components. Since it’s designed to retain data even when powered off, its biggest application is to hold the motherboard’s BIOS. This is a piece of software stored on the motherboard’s ROM chip with the purpose of booting up the computer and managing all the devices and connections within it.

Another big ROM vs. RAM difference is that ROM can be an external unit. Another common type of ROM is optical media like CD, DVD, and Blu-ray discs. It’s also used in various electronic devices like calculators, printers, fax machines, and pretty much anything that operates digitally and has some internal logic pre-programmed.

While it has certain similarities with flash storage, specifically due to being a non-volatile memory type, ROM doesn’t fall under the same category, as it’s designed to retain data without editing it. The confusion often comes due to motherboard manufacturers using flash memory to store BIOS, as it allows for easier updating than if the files were stored on a ROM chip.

Different ROM Types

Depending on how it works and how it’s used, there are four types of ROM:

1. Mask ROM – A type of memory that has its data programmed by the chip manufacturer and can be in no way modified or erased by the end user. The contents of this memory unit are protected by a “mask” of thin film in the process called photolithography.
2. Programmable Read-Only Memory – On this type of ROM, the memory unit has its data programmed by the user and is used mostly for storing encryption keys.
3. Erasable Programmable Read-Only Memory – An advanced version of PROM, this memory can be erased using UV light.
4. Electrically Erasable Programmable ROM – Another modifiable type of PROM. It’s easier to erase and reprogram via an electric charge, making it perfect for storing system settings.

The Biggest Differences Between ROM and RAM

As you can see, both types of memory have a similar purpose – storing data – but they also vastly differ in how they operate. RAM can only store data while it’s powered, while ROM can store data even without electricity, but its contents are oftentimes locked or, in certain cases, very hard to alter.

Aside from the differences we’ve already mentioned above, there are some other factors that differentiate the RAM vs. the ROM memory modules and how they’re used. 

• Data retention – RAM loses data when powered off, while ROM stores it permanently.
• Access time – RAM has a much quicker access time, especially with the introduction of DDR5 RAM, which drastically decreased the read and write times.
• Capacity – Internal ROM is usually just a couple of megabytes, and its capacity cannot be expanded. Meanwhile, RAM modules can stack up and expand the amount of available computer memory.
• Ease of writing – Usually, it’s impossible to write on ROM, or the process requires dedicated hardware, while RAM is constantly being refreshed.
• Appearance – ROM is usually a chip embedded in the motherboard, while RAM modules come in the form of sticks that slot into the motherboard and can be easily replaced.

Conclusion

As you can see, setting the ROM vs. the RAM side by side reveals more than a few key differences between the two. In fact, the only thing in common these two types of memory have is that they’re both important components of a modern computer system. Take one out, and the device becomes inoperable.

RAM is the high-speed, operational memory that’s constantly being written and rewritten, and it’s also easily expandable. Meanwhile, ROM contains critical data that computer systems can’t function without. Even though it has a lower storage capacity than RAM, its importance as the main memory for system boot makes it indispensable.