# DVD-ROM

> pre-pressed DVD that contains computer data

**Wikidata**: [Q2144513](https://www.wikidata.org/wiki/Q2144513)  
**Source**: https://4ort.xyz/entity/dvd-rom

## Summary
DVD-ROM is a pre-pressed DVD that contains computer data. It is a read-only optical disc format used for storing and distributing digital information, particularly software and data files. DVD-ROMs cannot be written to or erased, making them ideal for mass-produced content distribution.

## Key Facts
- DVD-ROM is a subclass of both DVD and machine-readable medium
- It follows CD-ROM in the evolution of optical disc technology
- The format has aliases including DVD Rom, Dvdrom, Dévédérom, and Digital Versatile Disc Read Only Memory
- It has a GND ID of 4585131-1 and is categorized under the commons category "DVD-ROM"
- DVD-ROM is different from DVD-RAM, which is a rewritable format
- The format is used in various applications including Xbox game media
- It has sitelink counts of 104 for DVD and 10 for DVD-ROM specifically
- The format is recognized across multiple Wikipedia languages including af, ca, de, es, fr, hr, pt, and vi

## FAQs
### Q: What is the difference between DVD-ROM and DVD-RAM?
A: DVD-ROM is a read-only format that cannot be written to or erased, while DVD-RAM is a rewritable format that allows multiple recordings and erasures. DVD-ROM is used for mass-produced content distribution, whereas DVD-RAM is used for data storage that requires frequent updates.

### Q: What are the main uses of DVD-ROM?
A: DVD-ROM is primarily used for distributing software, computer games, and other digital data that doesn't need to be modified. It's commonly used for operating system installation discs, application software, and reference materials like encyclopedias and databases.

### Q: How does DVD-ROM relate to other optical disc formats?
A: DVD-ROM follows CD-ROM in the evolution of optical disc technology, offering higher storage capacity and faster data transfer rates. It serves as the foundation for other DVD formats including DVD-R, DVD-RW, DVD+R, and DVD+RW, which are writable variations of the technology.

## Why It Matters
DVD-ROM revolutionized digital data distribution by providing a reliable, high-capacity storage medium that could be mass-produced at low cost. Before DVD-ROM, software and large data sets were distributed on multiple floppy disks or CD-ROMs, which were either too small in capacity or too slow in access times. DVD-ROM offered a solution with its 4.7 GB single-layer capacity, allowing entire software suites, operating systems, and multimedia applications to be distributed on a single disc. This standardization helped establish a universal format for software distribution, gaming, and data archiving that persisted for decades. The read-only nature of DVD-ROM also ensured data integrity and prevented unauthorized modifications, making it ideal for commercial software distribution and official documentation. Its widespread adoption created a foundation for the optical disc industry and influenced how digital content would be packaged and distributed for years to come.

## Notable For
- Being the standard format for commercial software distribution throughout the late 1990s and 2000s
- Providing 4.7 GB of storage capacity on a single disc, significantly more than CD-ROM
- Serving as the foundation for the original Xbox game console's optical media format
- Establishing a universal read-only optical disc standard that influenced subsequent optical media development
- Creating a reliable, tamper-resistant format for distributing copyrighted digital content

## Body
### Technical Specifications
DVD-ROM discs typically come in single-layer (4.7 GB) and dual-layer (8.5 GB) formats. The discs use a red laser with a wavelength of 650 nm to read data stored in microscopic pits on the disc surface. The data is arranged in spiral tracks that spin at variable speeds, with typical rotation rates between 200-500 rpm depending on the position of the laser reading head.

### Data Organization
The file system used on DVD-ROM discs is typically UDF (Universal Disk Format) version 1.02 or higher, though ISO 9660 and Joliet extensions are also common for compatibility with various operating systems. The data is organized in 2048-byte sectors, with additional error correction codes to ensure data integrity during reading.

### Manufacturing Process
DVD-ROMs are created through a pressing process where data is physically stamped onto a polycarbonate substrate. This process involves creating a glass master disc with the desired data pattern, which is then used to create metal stampers. The polycarbonate discs are injection molded using these stampers, and then metal and protective layers are added through sputtering and bonding processes.

### Compatibility and Standards
The DVD-ROM format adheres to the DVD Forum specifications and is designed to be backward compatible with CD-ROM drives, though not all DVD-ROM drives can read CD-RW discs. The format supports regional encoding for content control and includes built-in digital rights management features to prevent unauthorized copying of copyrighted material.

### Applications and Usage
Beyond software distribution, DVD-ROMs have been used for educational materials, reference works, medical imaging data, CAD drawings, and large databases. The format's reliability and cost-effectiveness made it particularly suitable for archival purposes, though it has been largely superseded by internet distribution and USB storage devices in recent years.

## References

1. Controlled Vocabulary for Dublin Core format
2. Wikibase TDKIV