SECONDARY MEMORY
The Secondary Memory is a permanent memory that used for the large amount of the information or data like : Audio, Video, Graphics, Image's, and other.
The secondary storage devices which are built into the computer or connected to the computer are known as a secondary memory of the computer. It is also known as external memory or auxiliary storage.
The secondary memory is accessed indirectly via input/output operations. It is non-volatile. The CPU can't directly access the secondary memory. First, the secondary memory data is transferred to primary memory then the CPU can access it.
CHARACTERISTICS OF SECONDARY MEMORY
These are some characteristics of secondary memory, which distinguish it from primary memory −
- It is non-volatile, i.e. it retains data when power is switched off
- It is large capacities to the tune of terabytes
- It is cheaper as compared to primary memory
Depending on whether secondary memory device is part of CPU or not, there are two types of secondary memory – fixed and removable . So permanently stores the data even when the computer is turned off or until this data is overwritten or deleted.
1) HARD DISK
It is a rigid magnetic disc that is used to store data. It permanently stores data and is located within a drive unit. The hard disk is also known as a hard drive. It is a rigid magnetic disc that stores data permanently, as it is a non-volatile storage device. The hard disk is located within a drive unit on the computer's motherboard and comprises one or more platters packed in an air-sealed casing. The data is written on the platters by moving a magnetic head over the platters as they spin. The data stored on a computer's hard drive generally includes the operating system, installed software, and the user's files and programs, including pictures, music, videos, text documents, etc.
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| Hard Disk |
COMPONENTS OF HARD DRIVE
The main components of a hard drive include a head actuator, read/write actuator arm, read/write head, platter, and spindle. A circuit board, which is called the disk controller or interface board, is present on the back of a hard drive. It allows the hard drive to communicate with the computer.
2) SOLID-STATE DRIVE
SSD (Solid State Drive) is also a non-volatile storage medium that is used to hold and access data. Unlike a hard drive, it does not have moving components, so it offers many advantages over SSD, such as faster access time, noiseless operation, less power consumption, and more.
As the cost of SSD has come down, it has become an ideal replacement for a standard hard drive in desktop and laptop computers. It is also suitable for notebooks, and tablets that don't require lots of storage.
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| Solid State Drive |
3) PEN DRIVE
Pen drive is a compact secondary storage device. It is also known as a USB flash drive, thumb drive or a jump drive. It connects to a computer via a USB port.
It comprises an integrated circuit memory chip that stores the data. This chip is housed inside a plastic or aluminum casing. The data storage capacity of the pen drive generally ranges from 2 GB to 128 GB. Furthermore, it is a plug and play device as you don't need additional drives, software, or hardware to use it.
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PEN DRIVE |
4) SD CARD
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SD CARD |
5) COMPACT DISK (CD)
CD stands for Compact Disk. CDs are circular disks that use optical rays, usually lasers, to read and write data. They are very cheap as you can get 700 MB of storage space for less than a dollar. CDs are inserted in CD drives built into CPU cabinet. They are portable as you can eject the drive, remove the CD and carry it with you. There are three types of CDs −
- CD-ROM (Compact Disk – Read Only Memory) − The data on these CDs are recorded by the manufacturer. Proprietary Software, audio or video are released on CD-ROMs.
- CD-R (Compact Disk – Recordable) − Data can be written by the user once on the CD-R. It cannot be deleted or modified later.
- CD-RW (Compact Disk – Rewritable) − Data can be written and deleted on these optical disks again and again.
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COMPACT DISK (CD) |
6) DVD (DIGITAL VERSATILE DISC)
DVD is short for Digital Versatile Disc or Digital Video Disc. It is a type of optical media used for storing optical data. Although it has the same size as a CD, its storage capacity is much more than a CD. So, it is widely used for storing and viewing movies and to distribute software programs as they are too large to fit on a CD. DVD was co-developed by Sony, Panasonic, Philips, and Toshiba in 1995.
TYPES OF DVDS
DVDs can be divided into three main categories which are as follows:
- DVD-ROM (Read-Only): These types of DVDs come with media already recorded on them, such as movie DVDs. As the name suggests, data on these discs cannot be erased or added, so these discs are known as a read-only or non-writable DVD.
- DVD-R (Writable): It allows you to record or write information to the DVD. However, you can write information only once as it becomes a read-only DVD once it is full.
- DVD-RW (Rewritable or Erasable): This type of discs can be erased, written, or recorded multiple times.