What is ROM?

What is ROM?

ROM, or Read-Only Memory, is a type of computer storage containing non-volatile, permanent data.

This data cannot be altered or deleted. ROM includes several types of memory devices that are used for different purposes.

For example, devices with an integrated ROM chip store their basic operating instructions. ROM also stores the firmware for peripheral devices like printers and scanners.

What is ROM Used For?

You might have heard of the term “ROM,” but do you know what it is and what it does? ROM stands for Read-Only Memory, and it’s used for the following purposes:

  • To hold the software that runs when the computer is powered on
  • To hold the software that generally can’t be changed by the user
  • To hold data that generally can’t be changed by the user
  • To hold the firmware for some hardware devices

What Can We Store in a ROM?

ROM is a type of non-volatile memory that can hold information. ROM can store the program that runs the computer, the firmware for the device, the data, which is useful for some types of devices, and the information about the device and its manufacturer.

The information stored in ROM can’t be modified once set, as it would damage other aspects of a device’s components or software. However, this doesn’t mean it’s useless!

For example, suppose you don’t need a particular feature on your phone but don’t want to lose your settings or data due to compatibility issues with another phone model.

In that case, you could use ROM to store those settings and get them back when upgrading.

The BIOS or UEFI is Stored in The ROM

If you’re having trouble getting your computer to boot up, or if it’s a new computer that you just bought, or you’re trying to get a virus or malware off of your computer, then you need to know how BIOS works.

The BIOS is stored in the PC’s ROM drive, which is the hard drive that looks like an old floppy drive with letters and numbers on it.

The BIOS is a set of instructions read by the motherboard when it powers up. If there were no BIOS in the PC, there would be nothing for the motherboard to read!

Types of ROM

There are several different kinds of ROM chips. The most common type is PROM (programmable read-only memory), which allows a microprocessor to save its setup information onto a chip.

This chip can be programmed, but once it’s programmed, you can’t change any of its data; it functions as a lock for the data on the chip.

Something else that sets PROM apart from all other chips is that you can program it in a unique way called mask programming, which involves creating an image of what the data should look like once you’ve written it onto the chip.

PROM and EPROM chips are usually based on SIMM technology or thin-film technology, which are related to EPROM (electronically erasable programmable ROM). Both types have their advantages and disadvantages.

For instance, SIMMs draw power while they’re being used (they use two nibbles per word) but don’t require as much power when they’re not being used because they only store one byte per word instead of two bits per word as with PROMs and EPROMs.

With these new forms of ROM come some new terms: PROMs are sometimes referred to as X-ROMs or CERAMIC RAMs because they’re manufactured using a ceramic material in an X shape with wires going through them.

EPROMs are often called EEPROMs because they contain tiny transistors that make them electrically erasable and programmable via electron beam, and flash memory is sometimes referred to as NOR or NAND memories because it uses bits at either end rather than alternating ones like SRAM does.

With flash memories you have determinate storage, meaning you know where each bit position starts and ends within each given sector so that it doesn’t matter if a bit isn’t in the proper position properly when reading or writing to it.

Difference Between ROM and Other storage Devices

ROM is the term used to describe memory that’s not removable. It is permanent but non-volatile.

Data you put in there won’t disappear when you turn off your computer or remove the disc from its reader. In contrast, other storage devices—like flash drives and USB memory sticks are more like “read-write” media because they can store and retrieve things depending on their power source.

In many cases, these devices have lower storage capacity than ROM does; for example, a 4 GB USB stick might only hold 4 GBs of data instead of storing everything at once.

But as you’ve probably noticed, “ROM” and “RAM” are sometimes used interchangeably in casual conversation. RAM isn’t part of the computer itself.

It’s an additional component inside your machine that provides temporary storage for some temporary data when necessary. Suppose you look at a website’s code or hear someone talking about playing video games on their phone/tablet/laptop/whatever.

In that case, the chances are good that both RAM and ROM skills will come up somewhere in their discussion!



Blinking Switch

RAM and ROM are two types of memory that play important roles in modern computing. RAM is volatile (meaning the power can be shut off, but the data can’t be), while ROM is non-volatile (the data stays on the computer even when the power is off).

Although they both store information, RAM handles everything happening on a computer, including running programs and storing data.

On a basic level, ROM stores specific instructions needed to boot up your computer—these instructions are in memory before your operating system boots up.

One type of program for your computer called an EPROM or EEPROM is erasable but writeable, so you can erase it and rewrite it.

ROM is Embedded on The Motherboard

ROM is Embedded on The Motherboard


A ROM (read-only memory) is a type of non-volatile memory that can be written to, but only by the manufacturer of your PC.

This means you can’t write new data to it. Still, it’s possible to make existing information in your computer persistent and safe from accidental changes. ROM chips are usually found on the motherboard of most PCs.

However, many newer models have made them removable so you can update them. Unlike hard drives, which contain all the information about what’s on your computer and how it works, ROM does not contain any programs or files.

It just holds many “pages” that tell the computer what things look like at specific points during startup and when certain tasks are performed.

Think of it as a map for your computer—it’s just not one where you can go from place A to B without hitchhiking over the Atlantic first.


Now you know everything there is to know about ROM. The most important thing to remember is that it’s a memory chip that holds data without any power source.

That makes it ideal for use in any small device or appliance because even if the power goes out, your clock radio will still be able to tell you the correct time when the power comes back on.