Storage Devices: CD-ROM MCQs Quiz | Class 9
Test your knowledge with this quiz for Class: IX, Subject: Computer Applications (Code 165), from Unit 1: Basics of Information Technology. This quiz focuses on the topic of CD-ROM, covering its role as optical storage, its read-only nature, and its common uses. Answer all the questions and click “Submit Quiz” to see your score and download a PDF of your answers.
Understanding CD-ROM Storage
A CD-ROM (Compact Disc Read-Only Memory) is a type of optical disc used to store data. It was a revolutionary technology for distributing software, music, and large volumes of information before the widespread availability of high-speed internet. Understanding its characteristics is fundamental to learning about the history and evolution of computer storage.
How CD-ROMs Work: Optical Storage
Unlike magnetic storage devices like hard disks or floppy disks, CD-ROMs use optical technology. A high-powered laser is used to burn microscopic indentations, called “pits,” onto the surface of a master disc. Flat, unburned areas are called “lands.” When you insert a CD-ROM into a drive, a low-powered laser beam scans this track of pits and lands. The reflection of the laser changes depending on whether it hits a pit or a land, and a sensor reads these changes as binary data (0s and 1s).
Key Characteristics of CD-ROM
- Read-Only Memory: The “ROM” in CD-ROM is crucial. It means the data is written once during manufacturing and cannot be altered, erased, or rewritten by the user. This made it ideal for permanent data distribution, like software or music albums.
- Optical Technology: It uses light (a laser) to read data, making it less susceptible to magnetic fields than floppy disks.
- Storage Capacity: A standard CD-ROM can hold approximately 700 MB of data, which was a massive amount at the time of its introduction. This is equivalent to over 450 floppy disks.
- Portability: CDs are lightweight and portable, making it easy to transport large files from one computer to another.
Common Uses of CD-ROM
CD-ROMs were the primary medium for a variety of applications, including:
- Software Distribution: Operating systems, applications (like Microsoft Office), and video games were sold on CD-ROMs.
- Audio CDs: The standard format for commercially released music albums for decades.
- Reference Materials: Digital encyclopedias (like Microsoft Encarta), dictionaries, and large databases were distributed on CDs.
- Multimedia Content: They were used for storing video clips, photo collections, and interactive educational content.
Comparison of Optical Discs
| Feature | CD-ROM | DVD-ROM | Blu-ray Disc |
|---|---|---|---|
| Typical Capacity | 700 MB | 4.7 GB (Single Layer) | 25 GB (Single Layer) |
| Laser Wavelength | 780 nm (Infrared) | 650 nm (Red) | 405 nm (Blue-Violet) |
| Primary Use | Software, Music | Standard Definition Movies | High Definition Movies, Games |
Quick Revision Points
- CD-ROM stands for Compact Disc Read-Only Memory.
- It is an optical storage medium, not magnetic.
- Data is read by a laser beam reflecting off pits and lands.
- Data on a CD-ROM is permanent and cannot be changed by the user.
- A standard disc holds about 700 MB of data.
- Successors to the CD include DVD and Blu-ray, which offer higher storage capacities.
Extra Practice Questions
- What is the main advantage of the read-only nature of a CD-ROM for a software company?
- Why is a CD-ROM called an “optical” disc?
- Name two types of data that were commonly distributed on CD-ROMs.
- How does a DVD store more data than a CD, even though they are the same physical size?
- What device in a computer is required to read a CD-ROM?
