You may be wondering what is secondary memory, common types of secondary memory, and its real-life examples. In this article, we try to make you more familiar with secondary storage and its important types with examples.
What is Secondary Memory?
Secondary memory is also called external memory. Secondary memory is used to save the software and data permanently before closing the computer. The secondary memory is slower in speed than the main memory in terms of data storage and retrieval.
Characteristics Of Secondary Memory
Following are some important characteristics of secondary:
- Store Data Externally
Secondary memory refers to external storage devices used to permanently store data or information.
- Stable In Nature
Secondary storage, on the other hand, is stable in nature, which means that instructions are first transferred to the main memory and then back to the central processing unit.
In secondary memory, information is stored on external storage devices and is not directly accessible by the processing unit.
- Permanent Data Storage
Secondary memory is unchanged in nature, meaning that information is stored permanently in the event of a power outage. The data is intact unless the user intentionally deletes it.
- Higher Storage Capacity
Secondary memory refers to external storage devices such as hard disk, optical disk, compact disk, flash drive, magnetic tape, etc. These devices have high storage memory with significant storage capacity, in the range of GIGABYTE to TB.
Types Of Secondary Memory
Following are the most common types of secondary memory:
- Floppy Disk
- Magnetic Tape
- Optical Disc
- Zip Drive
- Digital Disc
- Hard Disk
Soft disk or floppy disk is the secondary memory that is still used in offices and companies despite its low capacity compared to the new memory. It consists of a thin flexible circular piece of magnetic material enclosed in a plastic case that may be square or circular.
Information is stored in concentric circles. The name of these circles is TRACK. Each groove consists of several sectors or SECTOR. However, a whole segment is called a CLUSTER.
Floppy disks were very much in use in the 1980s and 1990s, particularly with home computers, such as the Macintosh and IBM home computers, to share programs, send and receive data, and take backups.
Before the discovery of hard disks, floppy disks were used to store the operating system and home computer programs as well. In the early nineties, the spread of the Internet was also very large, which led to the use of other storage and data transfer devices with larger storage capacities. This will lead to a decrease in the use of floppy disks.
Magnetic tape is one of the types of secondary storage that is written in tracks on magnetic plastic material. It is one of the external memories that is not used much anymore. In the past, due to its cheapness and ability to store information in high volumes and its long shelf life, it has been very suitable.
One of the most important uses of magnetic tape, due to its large storage capacity, is primarily to make backup copies of files. The scope of its use has also been expanded to save music such as (audio cassette) and audio and videotapes.
It is similar to the magnetic tape in the way it works for ordinary audio tapes or audio and videotapes, and it differs from discs where the data is accessed sequentially. Therefore, its speed is considered low and it is not used in direct interaction with the computer. But is used to create backup copies and save and is often used with large computer systems.
It is a disc coated with plastic that can save digital data in the form of small pits on the surface, read by a laser that scans the surface. . One of the disadvantages of optical discs is that they are subject to scratches, which leads to their peeling and thus leads to complete or partial damage to the disk.
Zip drive is similar to floppy disks, but it has the ability to store a very large amount of data, starting with a hundred megabytes.
DVD /Digital Disc
It is called (DVD) is an optical disc used to store data, and it can store movies of high quality in terms of clarity and sound. It is similar to a CD in terms of dimensions (12 cm) but has a different code and a much higher density. The disk can hold 4.7 gigabytes of information.
This type of disk can write information on one or two sides, as well as in one or two layers. The number of sides and layers shows the disk’s ability to absorb information. These digital disks are available with a length of 8 cm with a storage capacity of 1.5 gigabytes.
Types of DVDs
DVDs are consists of the following three main categories which are as follows:
- DVD-ROM (Read-Only): These DVDs contain media that is already recorded on them like songs, movies, etc. As the name shows, the data on these discs cannot be written or erased. So these discs are known as a read-only DVDs.
- DVD-R (Writable): These DVDs enable the users to record or write information. However, the information can only be written at once as it becomes a read-only DVD once it is full.
- DVD-RW (Rewritable or Erasable): This type of DVD is capable to be erased, written, or recorded several times.
Hard disk is another secondary memory that will be very suitable for storing programs and data for a long time. The hard disk is made of several parallel circular plates made of glass or metal that have a magnetic cover. A motor rotates it and there is a head on each side of the circular plate for reading and writing information.
One of the most important features that distinguish a hard disk from another is its storage capacity and rotation speed. There are three different types of hard disks:
- SCSI hard disk
- IDE hard disk
- SATA hard disk
Most computers today contain a hard disk. and the large computers, such as servers contains huge numbers of hard disks. But the presence of a hard disk is not necessary to operate the device. The main reason for using these billions of hard disks is that their ability to hold a lot of data after a computer is shut down.
Secondary Memory Examples
Some important examples of secondary memory are as follows:
- Solid-State Drive: SSD (Solid State Drive) is also a non-volatile memory that is used to store and retrieve data. SSD is not a hard disk. It provides faster access time, noiseless operation, less power consumption, and more.
- Pen Drive: Pen drive is compact secondary storage known as a USB flash drive. The USB port is used to connect this device with the computer. Its purpose is to store and transfer data between computers.
- SD Card: SD Card stands for Secure Digital Card. It is the most commonly used secondary memory in portable and mobile devices like smartphones and digital cameras.