What Is A CD-ROM?

Date First Published: 11th March 2024

Topic: Computer Systems

Subtopic: Computer Hardware

Article Type: Computer Terms & Definitions

Difficulty: Medium

Difficulty Level: 4/10

CONTENTS

Advantages and Disadvantages Of CD-ROMs
Difference Between A CD and a CD-ROM
History

Learn more about what a CD-ROM is in this article.

A CD-ROM is a CD used as a read-only optical memory device. This type of CD can be read, but not written to by a computer with an optical drive. Before being replaced by higher-capacity DVDs and online downloads, CD-ROM discs were often used for storing software for distribution for suppliers in the 1990s and 2000s.

Advantages and Disadvantages Of CD-ROMs

The advantages of CD-ROMs are:

CD-ROMs can be read by most computers and CD drives, making them a widely compatible software distribution method.
They can hold large amounts of data, including text, images, and audio. This makes them ideal for storing and distributing software.
They do not require an internet connection to access them, meaning that software can be accessed online. This is useful for organisations that do not have a reliable internet connection.

The disadvantages of CD-ROMs are:

Compared to USB flash drives and hard drives, storage capacity is more limited. A single disc can only store 700 MB of data.
They are fragile and can be easily damaged by scratches, which can make them unusable.
Limited updating capacity. Once a CD-ROM has been distributed, it cannot be updated, meaning that a new version of the software must be created and distributed on a CD-ROM if a new feature is added or a bug is discovered.

Difference Between A CD and a CD-ROM

CD-ROM discs and audio CDs are physically identical and store and retrieve data in the same way. They both use a laser beam to read the data stored on them. The main difference between a CD and a CD-ROM is that a CD is used for audio content and can be written to, whilst a CD-ROM is used for storing and distributing data, such as software and can only be read, meaning that data cannot be altered.

An optical drive can spin a CD-ROM disc at a much higher speed than an audio CD player. A CD spinning at the standard rate for audio playback supports a data transfer rate of approximately 150 KB/s. CD-ROM drives are classified by how many times faster they can spin with most drives capable of over 40x (61.44 MB/s).

History

The original data format for CD-ROM was defined by Philips and Sony in the 1983 Yellow Book. Other standards are used in combination with it to define directory and file structures, including ISO 9660, HFS (Hierarchical File System, for Macintosh computers) and Hybrid HFS/ISO.