Secondary memory is computer memory that is non-volatile, persistent and not immediately accessible by a computer or processor. It allows users to store data and information that can be retrieved, transmitted, and used by apps and services quickly and easily. Secondary storage is another name for secondary memory.
In this article, we will dive deeper into Secondary Memory according to the GATE Syllabus for (Computer Science Engineering) CSE. Keep reading ahead to learn more.
Table of Contents
- What is Secondary Memory?
- Use of Secondary Memory
- Types of Secondary Memory
- Secondary Memory Devices
- Video on Secondary Memory
What is Secondary Memory?
Memory in a computer refers to the physical components that are used to temporarily or permanently store programmes or data. It’s a collection of registers.
Primary memory is very volatile and has a finite amount of storage space. As a result, having a second type of memory with a bigger storage capacity- from which programs and data are not lost whenever the computer is turned off is critical. Secondary memory is the term for this form of memory. Programs and data are stored in secondary memory. Auxiliary memory is another name for it. It differs from primary memory in that it is non-volatile and not directly accessible by the CPU. Secondary storage devices, often known as external storage devices, have substantially more storage space and are less expensive than primary memory.
Use of Secondary Memory
Secondary memory is mainly used for different purposes. The primary purpose of using it is as follows:
1. Permanent storage – Primary memory, as we all know, retains data only when the power is on and loses data when the power is turned off. As a result, we require a secondary memory that can keep data indefinitely even if the power supply is turned off.
2. Large storage – Secondary memory provides a significant amount of storage space, allowing us to store large amounts of data such as films, photographs, audio files, and other items permanently.
3. Portable – Some of the secondary devices can be removed. As a result, one can store data and transfer them effortlessly from one device to another.
Types of Secondary Memory
There are two types of secondary memory:
1. Fixed Storage
A fixed storage device in secondary memory is an internal media device used to store data in a computer system. Fixed storage is sometimes known as hard drives or the fixed disc drives. In most cases, the computer system’s data is saved in the fixed storage device that’s incorporated into a given system. Fixed storage does not preclude their removal from the computer system; with the assistance of an expert or engineer, you may remove the fixed storage device for repairs, upgrades, or maintenance, among other things.
Types of fixed storage:
Here are the different types of fixed storage:
- Hard disk drives (HDD)
- SSD (solid-state disk)
- Internal flash memory (rare)
2. Removable Storage
Removable storage refers to an external media device that is mainly used to store data on a computer system in secondary memory. The disk drives or the external drives are common names for removable storage. It’s a removable storage device that can be inserted or withdrawn from the computer as needed. We can uninstall them effortlessly from a computer system while it’s still running. We can transfer data from any computer to another one simply using removable storage devices because they are portable. Also, removable storage devices provide high data and information transfer speeds that the storage area networks (or SANs) are known for.
Types of Removable Storage:
Here are the types of removable storage:
- Optical discs (such as DVDs, CDs, Blu-ray discs, etc.)
- Floppy disks
- Memory cards
- Disk packs
- Magnetic tapes
- Paper storage (such as punched cards, punched tapes, etc.)
Secondary Memory Devices
Here are the most commonly utilised secondary memory devices:
1. Floppy Disk – A floppy disc refers to a magnetic disc housed in a square plastic container. It is primarily used to store information and then transfer it from one device to another. There are two sizes of floppy discs (a) Size: 3.5 inches, 1.44 MB storage capacity (b) Size: 5.25 inches and 1.2 MB storage capacity. A computer must consist of a floppy disc drive for using a floppy disc. Such a storage device is now obsolete, and DVDs, CDs, and flash drives have taken its place.
2. Compact Disc – A Compact Disc or the CD is a type of secondary storage media that is widely utilised. Its surface is covered in tracks and sectors. It is composed of polycarbonate plastic and has a round form. CDs have a data storage capacity of up to 700 MB. A CD is also known as a CD-ROM (Compact Disc Read-Only Memory) because computers can read the data on it but not write new data onto it.
There are two types of CDs:
- CD-R or compact disc recordable – It is not possible to remove data that has been written onto it; it can only be read.
- CD-RW or compact disc rewritable – It’s a particular kind of CD that allows us to wipe and rewrite data as many times as we desire, so It’s also known as an erasable CD.
3. Digital Versatile Disc – DVD stands for Digital Versatile Disc. It resembles a CD, but it has a larger storage capacity; up to 4.7 GB of data can be stored. To use a DVD on a computer, a DVD-ROM drive is required. Video files, such as movies or video recordings, are commonly saved on DVDs, which may be played with a DVD player. There are three different kinds of DVDs available:
- DVD-ROM or Digital Versatile Disc Read-Only Memory – The manufacturer writes the data on the DVD-ROM, and the users can only read it; they cannot create new data on it. For example, a movie DVD has already been written by the maker, and we can only watch it; we cannot add new data to it.
- DVD-R or Digital Versatile Disc Recordable – You can write data on a DVD-R, but only once. It is not possible to remove data that has been written onto it; it can only be read.
- DVD-RW or Digital Versatile Disc RW (Rewritable and Erasable) – It’s a particular kind of DVD that allows us to wipe and rewrite data as many times as we desire. It’s also known as an erasable DVD.
4. Blu-ray Disc – It resembles a CD/VD, but it can actually hold up to 25 GigaBytes data or information. You’ll need a Blu-ray reader if you wish to use a Blu-ray disc. The name Blu-ray comes from the technology used to read the disc: ‘Blu’ comes from a blue-violet laser, and ‘ray’ comes from an optical ray.
5. Hard Disk – Hard discs are storage devices designed to hold a lot of information. Hard discs, often known as hard disc drives, are available in a variety of storage capacities. (For example, 256 GB, 500 GB, 1 TB, and 2 TB). It is made up of platters, which are a collection of discs. The dishes are stacked one on top of the other. They have a magnetic coating on them. Each platter is made up of a number of invisible circles, each of which has the same central track. Internal and external hard discs are the two types of hard discs.
6. Flash Drive – A flash drive or pen drive is available in a variety of storage capacities, including 1, 2, 4, 8, 16, 32, 64 GB, and 1 TB. Data is transferred and stored using a flash drive. To use a flash drive, it must be plugged into a computer’s USB port. A flash drive is quite popular nowadays because it is simple to use and small in size.
7. Solid-state Disk – A Solid-state Disk (SSD) is a data storage and retrieval device that is non-volatile. It’s faster, makes no noise (since it doesn’t have any moving parts like a hard drive), uses less electricity, and so on. If the price is right, it’s a perfect replacement for regular hard drives in laptops and desktops, and it’s also ideal for tablets, notebooks, and other devices that don’t require a lot of storage.
8. SD Card – A Secure Digital Card (SD Card) is commonly used to store data in portable devices such as cell phones and cameras. It comes in a variety of capacities, including 1, 2, 4, 8, 16, 32, and 64 GB. You can access the data present in the SD card by removing it from the device and inserting it into a computer using a card reader. The data in the SD card is stored in memory chips (which are included in the SD card), and there are no moving elements like there are on a hard disc.
Video on Secondary Memory
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