What Is A ROM In A Computer? Types & Importance Explained!

A computer is composed of tons of small and big hardware components, and ROM is one of them. It is a small machine and one of the have-must hardware of a computer system that allows it to store the data permanently.

what is a rom
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What does it mean? I know, now your curious mind is coming up with zillions of questions about the ROM, including a possible question about its understandable definition that could sit well in your mind.

This page would provide you with all the information about ROM, ranging from the list of its types to its main operational objective and the components. So, grab a cup of hot coffee and relax for a brief tour of the world of ROM. It’s going to be worth it!

What Is A ROM Chip?

ROM (Read Only Memory) is a data storage device that comes with a computer system. When it comes to a computer system, ROM is attached to a Motherboard using a BIOS chip that covers a small area. Although ROMs were only associated with computers in the past, now they can be found in several types of electronic devices.

A ROM is a non-volatile memory type which means if you turn off a computer and turn it on afterward, the previously stored data would be still saved. In other words, it does not require a continuous power supply. ROM is a non-editable type of memory and can not be changed. The main intent of manufacturing this type of memory device is the permanent storage of data to be used for specific types of software like video games, video editors, and business applications.

What Is ROM Used For In A Computer?

ROM, like any other small or big hardware, allows the computer to perform specific operations. It is tasked with responsibilities in assisting the computer during the system start-up. When you press the ”Start” button of the computer, ROM takes charge to perform the initial operations. 

It includes ensuring all the hardware devices are attached to the computer system and are functional. If a critical importance device is not functioning, it would warn the user and would not proceed further. Without completing these initial operations, your computer system would not hand over the charge to the CPU which is supposed to initiate the Windows Software. 

Yes, the windows would not start without successful initial operations which require the involvement of ROM. The importance of ROM lies in the fact that it carries the start-up codes of a computer. No ROM means no start-up codes, and no start-up codes mean the computer can’t be run.

History Of ROMs

The history of ROM is a series of significant events hinting at the massive change Read-Only-Memory has gone through over the decades. It started with the Post-war era which proved to be crucial for the evolution of general-purpose computers and their hardware components. From GPUs to RAMs and Motherboards, every hardware component went through a major digital evolution in the Post-war era. 

The first recorded use of the ancient type of Read-Only-Memory was made by ENIAC in 1948 which relied on a disintegrated circuitry system. When the Disintegrated Circuitry System was dominant in computers, Wen Tsing Chow came up with his invention of  PROM (Programmable-Read-Only Memory) In 1956.

This invention allowed the users to make modifications to the non-programmable ROM depending upon the purpose and was a relief for many. Despite all of this, Disintegrated Circuitry Systems were common in the early 60s, and disintegrated ROMs were being utilized by major tech companies, such as IBM, for their early computer families. 

However, the norm of using disintegrated ROMs changed with the invention of Integrated Circuitry systems in the mid-60s. This invention led to the rise of Mask ROMs which were basically non-programmable. Soon, the major tech companies modified their general-purpose computer systems for the inclusion of Mask ROMs. 

For a few years, Mask ROMs and PROMs retained the global ROM market and remained undefeated. But in 1972, a team of Yasuo Tarui, Yutaka Hayashi, and Kiyoko Naga invented EEPROM (Electrically erasable programmable Read-Only Memory) which was intended at solving the issues posed by Mask ROMs and PROMs. 

Unlike Mask ROM, EEPROM could be programmed in place to make the necessary modifications to the program hosted. A Flash Memory is a fine example of an EEPROM that can be reprogrammed as many times as one wants. Both the Flash Memory and Mask ROMs are used by a large number of PC users today and are expected to remain part of the computer systems until the invention of their successors. 

Here is a short timeline of the major events involving the invention of different types of ROMs that, more or less, contributed to the history of ROMs.

1965SylvaniaThe company built Bipolar TLL type ROM capable of 256 bit
1969Intel1kb ROM containing 3301 chip made it to the market
1970RadiationBuilt one of the earliest 512-bit PROMs in the 70s
1972IntelFirst-ever 2 kb EPROM introduced under the title of 1702
1976ToshibaFirst-ever EEPROM capable of 2kb invades the international market
1980MotorollaThe American company introduced 16kb EEPROM 
1984NECOne of the first 1Mb EPROM devices appeared
1990NECAn EPROM type memory device powered by 16Mb capacity is introduced
1995AKM, Hitachi Hitachi presented the 16Mb MROM supported by CMOS

Types Of ROMs

The following are the Three primary types of Read-Only-Memory with each carrying different properties.

PROMAs the name suggests, PROM is a programmable type of memory. A PROM is like an empty chip that can be used to program it the way one wants
EPROMAn EPROM is a revolution in the world of computer memory. It is because of the fact that you can add and erase its data as many times as you want
EEPROMUnlike an EPROM which requires one to completely erase the data for a single edit, an EEPROM allows the editor to make small edits without going through a long process of completely erasing the data

Parts Of Computer ROM

A Read-Only-Memory aka ROM is the result of a union among three components. These components together make a ROM operational. Without any of these, a ROM would not be a ROM but a piece of junk. For better understanding, check out these components below.


A decoder is a component of a Read-Only-Memory which is composed of a circuitry system that decodes the Binary form to the Decimal form.

OR Logic Gates

Logic Gates are directly connected to the decoders using their input and output system. In other words, Logic gates communicate with the decoder using the output of the latter. While it is an output for the decoder, it acts as an input for the logic gates.


In the ROM chip, a diode is used to establish a connection with a capacitor in each row. This connection is meant to get control of capacitors and to turn them on and off. Apart from that, unlike its counterparts, the diode enables a one-sided current flow to the various parts of the Read-Only-Memory.

Frequently Asked Questions

Wrap Up

In biological terms, a Read-Only-Memory is like the nerve cells of a computer brain allowing it to permanently store the data and operate accordingly. It is like the default memory of a computer which, if deleted, would disable the computer to start up and perform data-storage-related tasks. 

It’s also like the internal radar system of a computer, specifically designed to scan the functionality status of each and every hardware component of a computer and to ensure these components are properly integrated into the computer system.

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Bilal Khan
Bilal Khan

Bilal might look like a Bearded Caucasian right out of a Viking movie but trust me he's a native Pakistani. He has a long list of hobbies among which staying updated on the Latest Technology and Hardware happens to be on the top. If you are looking for detailed hardware explanations through no tricky terminologies, follow him to read Tech Content curated perfectly for the human brain.

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