Floppy Disk and Optical Memory

Floppy disk:  

It has a magnetic covering and is a flat, 3.5-inch disk made of polyester film. This disk has a storage capacity between 720KB and 2.88MB (as shown in picture). There is only one plastic disk inside. It provides access at a slower rate than a hard drive. Sector technique is used to store the data. Pie-shaped segments sever the disk's surface. A distinct number is given to every section. An address consisting of the sector number and the individual data record number can be used to locate data. It is extremely portable, light, and the data can be moved around with ease. Originally employed as the primary storage device, it is now utilized to transfer data between computers. Floppy drives are required for it to function. Due to the open or uncovered surface where data is stored, it is unreliable as a hard disk. As a result, it might be impacted by nearby magnetic fields and dust particles.

Optical Memory:

It is the most suitable replacement for magnetic storage. A light beam is used in the process of optical memory. The fourth generation of computers is where it was developed. It is mostly used to carry or transmit data from one device to another as well as to store music and video and make backups. For it to function, an optical drive is required. Compared to hard drives and flash memory, it reads and writes data more slowly.

Advantages:

• Optical disks cost less.
• Data can be retained for a longer time.
• Because of their compact size and light weight, they are manageable and portable.

The following categories of optical memory exist:

• CD-ROM: Compact Disk Read-Only Memory is what it stands for. It can hold 700 MB worth of data. It has a 90-minute audio storage capacity. A layer of aluminum alloy is placed on one side of the hard circular plastic used to cover CDs. This metal preserves data. It is covered in a very thin plastic layer for protection. For CD to function, CD-drive was required. Large-scale static data storage applications like directories, online database encyclopedias, and multimedia application archiving are best stored on CD-ROM.
• WORM: The phrase means "Write Once, Read Many." It has a similar appearance to CD-ROM, except they typically have golden tones rather than silver. These disks can be used by the end-user organization to store its own data or material, typically stiff graphic or photographic pictures. A magnetic substance that can switch magnetic polarity once when heated coats the disk surface. A strong laser beam warms tiny areas in the magnetic medium that enable it to accept magnetic patterns for data storage. By illuminating the magnetic layer with a weaker laser beam and observing the reflected light, data can be read. In place of microfilm, WORM is utilized to store digitized document images.
• VCD: Its name, Video CD, refers to a type of compact disk that can hold video for up to 74 minutes. Additionally, VCD can be used to store audio data associated with video pictures.
• CDRW: For Compact Disk Rewritable, it is an acronym. The user can write and read several times using this drive. A CDRW drive can play a standard CDROM disk.
• DVD: For Digital Versatile Disk, it is an acronym. It can store anything from 4.7GB to 17GB. Its size and shape are comparable to CDs (Compact Disks), but its storage capacity is different. It's because chemical components and data are compressed before being stored. For it to function, a DVD drive is needed. DVDs move at a slower pace than CDs (basically read and write). Multimedia programs and movies that need a lot of room for both video and graphics storage are stored on DVDs.
• BD: Its acronym is Blu-ray disk. It has a storage capacity ranging from 25 GB to 50 GB. For it to function, a BD drive is necessary. Its size and form are comparable to DVDs and CDs.
• Erasable Optical Disks: The erasable optical disks (EOD), which are essentially magneto-optical disks, can be written onto several times. Access occurs more slowly (i.e. 48 Milliseconds with 1 Megabytes per second transfer rate). Large read and write heads with a laser and a magnetic coil are used. They have large capacity for PC configuration. As opposed to fixed magnetic disks, several Gigabytes per cartridge are detachable.

Virtual Memory

As main memory and secondary disk storage, computers can store many kinds of memories. While main memory is expensive and has a small or limited amount of storage, secondary disk memory is inexpensive and offers a large amount of storage. Therefore, it is important to employ some secondary disk memory as a main memory when doing data processing; this type of memory is referred to as virtual memory. Virtual memory is typically used for the following two reasons:

• Users agree to broad accessible memory space without actual main memory size restrictions.
• To enable the effective and cost-effective sharing of memory space among several users in a multi-programming system.

Reference:

Ghishing, Er.Ashim. Computer Science. Kathmandu, Nepal: Benchmark , 2008.