Secondary Storage Device is also called Auxiliary Storage Device. It is not a part of the computer. It is added separately to the computer. The data that is stored in it. It is permanent. That is, when the computer is turned off, the stored data in it is not deleted.

According to the requirement, it can be opened by saving files or folders in it in the future. Or you can improve it. And it can also be deleted by the user. Its storage capacity is more Secondary Storage Device can store many times more data than primary memory, which is transferable and the speed of accessing data is slower than Primary Memory. Secondary Memory includes floppy disk, hard disk, compact disk, optical disk, memory card, pen drive, etc.


Hard Disk

A hard disk or HDD is the same thing, it is a physical disk that we use to store all the small files of our computer. The difference between hard disk and RAM is that hard disk is the thing that is used to store, but RAM is used to run the things kept in that storage. When we shut down the computer, then anything lying in the RAM is cleared. However, if the computer is turned off in HDD, the erased data is not erased.

A disk rotates inside the hard disk, the faster the disk rotates, the faster it can store or read data. We measure the speed of rotation of the hard disk in RPM (Revolutions Per Minute). Most hard disks are of 5400 RPM or 7200 RPM, obviously, the hard disk of 7200 RPM is much faster than 5400 RPM.

Structure and Procedure

The hard disk consists of a magnetic disk. It has ahead for reading and writing data. The hard disk has a central shaft. In which the magnetic disk is attached. Data is not stored on the upper surface of the hard disk and on the lower surface. Data is stored on all other surfaces. The plate of the disc consists of Track and Sector. A sector has a data store, a sector has a 512-byte data store.

It takes three types of time to store and read data. Which is as follows.

1. Seek Time: -. The time taken to reach the track that reads or writes the data in the disk is called the time.

2. Latency time: - The time it takes for the data in the track to reach the sector is called latency time.

3. Transfer Rate: - The time it takes to write and read data in the sector. This is called Transfer Rate.

Floppy Disk

It is made of plastic with a layer of ferrite. It is made of very flexible plastic. Therefore it is called Floppy Disk. Which has a plastic hinge. Which is called a jacket. A point is formed in the middle of the floppy, which causes the disk of this drive (disk) to rotate. This Floppy Disk has 80 data tracks and 64 words can be stored in each track. It works against Magnetic tape. Which rotates at a rate of 360 RPM per minute. Due to which the problem of the breakdown of its recording head arises.

Floppy is of two types from the point of view: -

  • 5½ diameter floppy disk
  • 3½ diameter floppy disk
  • 5½ Diameter Floppy Disk -  It was invented in 1976 and is also protected by a plastic jacket. Its storage capacity varies from 360 KB to 2.44 MB.
  • 3½ diameter Floppy Disk -  It was first used in Apple computers. Which is smaller than the previous floppy. Its storage capacity varies from 310 KB to 2.88 MB.

Magnetic Tape

Magnetic tape is also a storage device with a thin lace on which the coating of Magnetic Ink is done, it is used to store Analog and Digital Data. It is like the old-time audio case Magnetic Tape is used to store a large amount of data. They are cheap. Even today it is used to create a data backup.

Optical Disk

Optical Disk is a flat, circular polycarbonate disk on which data is stored as pits inside a flat surface, in which data is stored by optical.

There are two types of optical discs.

CD: - First of all, let's talk about the CD, we also call the name of Compact Disc, it is an optical medium that saves our digital data. Once upon a time when we used reel cassettes, CD's encroachment completely eliminated cassettes in the market. About 700 MB of data can be saved on a standard CD. The data in the CD is saved in the form of a dot, in fact, the laser sensor in the CD drive reads the reflected light from the dot of the CD and creates an image in our device.

DVD: - DVD i.e. digital versatile disk, DVD started after CD, although both CD and DVD look the same, their data capacities differ, more data can be saved in DVD than CD. . That means the user can save data from about 4.7 GB to 17 GB in DVD. After the arrival of DVDs, the market saw a huge reduction in the demand for CDs.

Flash Drive

Pen Drive itself is known as Flash Drive, nowadays most of the Flash Drive is used to store data, it is an external device that is used separately in the computer. It is also very small and light in size, store data can be read in it and it can also be improved.

Flash Drive has a small Printed Circuit Board which is covered with plastic or metal cover so it is strong. It is a plug-and-play device. Today it is normally available in 2 GB, 4 GB, 8 GB, 16 GB, 32 GB, 64 GB, 128 GB etc. capacities.

Memory Card

A memory card is considered a small storage medium that is commonly used to store information. A memory card is a type of storage media often used to store photos, videos, or other data in electronic devices. Devices that typically use memory cards include digital cameras, digital camcorders, handheld computers, MP3 players, PDAs, cell phones, game consoles, and printers. It is also used for small, portable, and remote computing devices.

The amount of storage space can vary depending on the type of memory card. However, in general, most memory cards today range in size from 4 GB (gigabytes) to 128 GB. The old memory cards were smaller than 4 GB.

There are various types of memory cards available on the market, the links to more details of the most commonly used types of memory cards are listed below.

  • CF (CompactFlash)
  • MicroSD
  • MMC
  • SD Card
  • SDHC Card
  • SmartMedia Card
  • Sony Memory Stick
  • xD-Picture Card

Zip Drive

The zip drive is a small, portable disk drive used primarily to backup and stores personal computer files. The trademarked ZIP drive was developed by Iomega Corporation in the mid-1990s. Zip drives and disks come in two sizes. The size of 100 megabytes is actually equal to 100,431,872 bytes of data or 70 floppy diskettes.

There is also a 250-megabyte drive and disk. Iomega ZIP Drive comes with a software utility that lets you copy the entire contents of your hard drive to one or more ZIP disks. It was popular at launch because the cost per storage unit was lower than that of a hard disk, and it could store a larger amount of data than a floppy disk. The zip drive was durable and reliable capable of fast data transfer.

Magnetic Disk

A magnetic disk is a storage device that uses a magnetization process to write, rewrite, and access data. It is covered with a magnetic coating and stores data in the form of tracks, spots, and sectors. Hard disks, zip disks, and floppy disks are common examples of magnetic disks.

The magnetic disk mainly consists of a rotating magnetic surface and a mechanical arm that moves on it. The mechanical arm is used to read and write from the disk. The data on the magnetic disk is read and written using a magnetization process.

The data is organized as a track and sector on a disk, where the tracks are circular partitions of the disk. The track is divided into regions that contain blocks of data. All reading and writing operations on magnetic disks are performed on the spheres.


I am an engineer by profession but being a blogger is my old day's dream to create my site for those who are more curious about my birthplace than I am coming from (India). the current city lives in Navi Mumbai, India

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