Question

Can be read many times, but written after its manufacture only once

Short answer

The object is a CD-R, DVD-R, or BD-R.

Step-by-step solution

Identify Clues

Consider the properties of the item described. The item is something that can be read multiple times but can only be written on once after its manufacture. This suggests that once written, the content cannot be altered, which is key to identifying the object.

Assessing and Matching Characteristics

Next, match these characteristics to potential candidates. Items known for being read multiple times include books, documents, CDs, DVDs, and Blu-Rays. Among these, digital storage media like CDs, DVDs, and Blu-Ray discs are typically written once after manufacture, such as in the case of CD-R, DVD-R, and BD-R formats.

Selection

From the potential options, choose the one that fits all the specified criteria. A CD-R, DVD-R, or BD-R fits the description as they can be read many times but are designed to only allow data to be written once.

Key concepts

CD-R

A CD-R, which stands for Compact Disc-Recordable, is a type of digital storage medium that allows data to be written onto it once. After the initial information is recorded, it cannot be overwritten or erased.
This characteristic makes CD-Rs ideal for storing files that need to be preserved without modification. People often use them to save music, software, and important documents.
The technology behind a CD-R involves a special dye layer that changes when exposed to a laser. This dye layer creates marks that a CD player reads as data, remaining unchanged over time.

• Capacity: Typically holds up to 700 MB of data.
• Usability: Suited for single-time data storage with frequent reading.
• Durability: Sensitive to scratches and sunlight but good for archival purposes if handled properly.

DVD-R

A DVD-R, or Digital Versatile Disc-Recordable, works similarly to a CD-R but offers more storage capacity, making it valuable for videos, software, and extensive data storage. Like a CD-R, once data is burned onto a DVD-R, it cannot be erased or rewritten.
The technology uses a laser to alter a dye layer in the disc, creating marks that represent data. This makes the disc readable in standard DVD players.
DVD-Rs are often preferred over CD-Rs when more space is needed.

• Capacity: Usually holds up to 4.7 GB of data per side.
• Applications: Ideal for storing video content and large files.
• Durability: Similar to CD-Rs, they require careful handling to avoid damage.

BD-R

BD-R, standing for Blu-Ray Disc Recordable, is a high-capacity digital storage medium commonly used for HD video and large data archives. Like CD-Rs and DVD-Rs, data is written to a BD-R using a laser but cannot be rewritten or erased once set.
The advanced Blu-Ray technology allows for even higher densities by recording onto a smaller area, enabling it to store large amounts of data.
Because of its high storage capacity and quality, BD-Rs are popular in digital video recording and storage of significant amounts of data.

• Capacity: Typically provides up to 25 GB per layer, with multiple layers increasing total capacity.
• Preferred use: Ideal for high-definition video and massive data backups.
• Handling: Requires careful storage to maintain data integrity due to susceptibility to scratches.

Read-Only Memory (ROM)

Read-Only Memory (ROM) is a type of memory in computers and other electronic devices that is pre-written with data. Once this data is written during the manufacturing process, it cannot be modified or erased.
ROM is crucial for storing firmware or software that is essential for hardware operation. This makes it non-volatile, meaning it retains its information even when the device is powered off.
Various types of ROM exist, each catering to different needs in computing and electronics.

• Characteristics: Permanent data storage, not intended for frequent changes.
• Applications: Commonly used for firmware in computers, mobile phones, and embedded systems.
• Comparison: Unlike writable media like CD-Rs, ROMs are factory-set with data and not used for outside data storage.