Introduction of Compact Disk (CD) optical memory

Optical memory is a type of electronic storage medium that stores and retrieves data using a laser beam. If we categorize memory systems, optical memory falls under external memory in a computer system. There are numerous forms of optical memory.

What is Optical Memory?

Optical memory is a form of electronic storage that uses a laser beam to store and retrieve data. It was developed by Philips and Sony and released in 1982 in the fourth generation of computers. These memories use light beams for their operations and require optical drives for their operations. These memories are used for storing audio/video, backup and caring for data. Read/write speed is slower compared to hard disk and flash memory. Examples of optical memories are Compact Disk (CD), Digital Versatile Disk (DVD), and Bluray Disk (BD). Here, we have discussed only Compact Disk (CD) in brief.

What is Compact Disk (CD) Optical Memory?

It stores data and it has circular plastic, a single side of the plastic is coated by aluminium alloy which stores data. It is protected by an additional thin plastic covering. CD requires a CD drive for its operation. A CD could store much more data than a personal computer hard drive. The CD has storage typically up to 700 MB (up to 80 minutes audio).

Compact Disc

Types of Compact Disk (CD) Optical Memory

These are various types of CD as follows below.

1. CD-Read-Only Memory

The CD-ROM reached the market in 1985, expanding beyond audio to record optical data storage. CD-ROMs can be read by any computer that has a CD-ROM drive. The Yellow Book standard is followed by the CD-ROM.

2. CD-interactive

CD-i, which was released in 1993, could be played on CD players but not in a CD-ROM drive. The format was then adjusted so that it could be read by both. The CD-i adheres to the Green Book criteria.

3. CD-Rewritable

The metallic alloy used in the CD-RW reflected differently than normal compact discs. Because of this shift in reflectivity, a CD-RW was rendered unreadable by many early CD players. The Orange Book standard is followed by the CD-RW.

4. CD-Recordable

A compact disc (CD-R) is a disc that can be written to once and read numerous times. It follows the Orange Book, like the CD-RW, but unlike the CD-RW, the CD-R can be read by CD players released prior to its own introduction.

5. CD-ROM eXtended Architecture

The CD-ROM XA is an expansion of the conventional CD-ROM that permits simultaneous access to audio, video, and computer data. It adheres to the Yellow Book standard and was designed as a bridge between CD-ROM and CD-i.

6. Photo CD

The photo CD was invented by Kodak for the sole purpose of storing photographs in a digital format that could be accessed and altered on a computer. It first appeared in 1992 and was intended to carry 100 high-quality photos. It adhered to the Beige Book standard.

7. Video CD

The video CD, or VCD, was developed in 1993 in accordance with the White Book standard. VCD quality was designed to be equal to VHS recordings, however it has far lesser resolution than a current digital video disk (DVD).

Advantages of Compact Disk (CD)

• Portable: CDs are more compact and lightweight, they are easier to store and travel.
• Reliable: In that time, an entire software can be stored on one CD, so its very reliable for the software industries in the days.
• Multiple Applications: It is also adaptable. The higher capacity of the compact disc was exploited for uses other than storing digital audio. CDs became a popular media for distributing home films, software packages, and other digital content.
• Random Access: CD provides random data access. Users can use this random access to choose music tracks, specific files or data, or explore a menu via a user interface.
• Rewritable Formats: Another benefit of compact discs is the availability of rewritable versions such as CD-R and CD-RW.

Disadvantages of Compact Disk (CD)

• Inferior Capacity: CDs have more storage capacity than their predecessors, but subsequent storage mediums have more capacity. Storage capacity is lower than a hard drive or DVD, nowadays CD is not used at all.
• Older Technology: A compact disc’s limitation stems from its older read and write mechanism technology, which is based on 780nm wavelength.
• Inferior Quality: It should be noted that audio-video files with higher audio and video quality can be stored on DVDs and Blu-ray Discs.
• Durability Issues: Magnetic tapes are less durable than CDs. However, it is still fragile because it is easily scratched if not treated carefully. When exposed to severe heat and humidity, it might deform and become unusable.
• Obsolete Medium: Another issue of CDs is that they have become obsolete as better storage methods have become available.
• It’s also worth noting that compact discs aren’t suitable for backup storage because of their limited storage capacity, susceptibility to breakage, and obsolescence. It is preferable to use hard drives or solid-state drives.

Frequently Asked Interview Questions

1. Can the data on an optical disc be recovered?

If the data on a damaged optical disc is not too badly damaged, it can usually be retrieved. However, even if the data is being read from the disc, it may be corrupted.

2. What do you understand by CD-ROM?

It became a ROM (read only memory), in which you can not update or delete data. Only you can read data using a CD-drive.

3. What is optical memory storage of a Compact Disk?

The standard CD can store 72 minutes of music or 650 MB of data. An 80 minute CD can store 700 MB of data