What is Secondary Memory?
SECONDARY MEMORY
This type of memory is outside the CPU, hence it is also called external or auxiliary memory. Due to the fact that the primary memory of the computer is very expensive and most of the information kept in it gets destroyed when the power is turned off, neither we can expand it as desired nor we can store any information in it permanently. So we have to use secondary memory. Its price is comparatively less and the capacity to store data is very high. It has only one drawback that it takes time to write (ie store) and read (ie receive) data in these mediums.
That's why we store such information in it which has to be kept safe for a long time and which is not needed continuously. We can increase the secondary memory to any limit as per our requirement. This memory is in the form of some magnetic devices; For example, floppy disk, hard disk, magnetic tape, CD-ROM etc. Secondary memory is used for backup. When we do not need any data urgently, then it can be stored in a magnetic medium; For example, copying on floppy disk or magnetic tape is saved separately. This is often done to free up the hard disk, so that it can be filled with data that is needed and there is no space on the disk. The data stored in the backup device can be backed up or copied to the hard disk again whenever needed. Devices or devices related to secondary memory are also called mass storage media and devices.
TYPES OF SECONDARY SRORAGE DEVICES
- SEQUENTIAL ACCESS DEVICE
- DIRECT ACCESS DEVICE
■ Sequential Access Device :-
In computing, sequential access memory is a class of data storage devices that read stored data in a sequence. This is in contrast to random access memory where data can be accessed in any order. Sequential access devices are usually a form of magnetic storage or optical storage. While sequential access memory is read in sequence , arbitrary locations can still be accessed by " seeking " to the requested location . This operation , however , is often relatively inefficient .
Types of Sequential Access storage Device
□ Magnetic Tap
A storage technology that is read and written in a serial term. Magnetic tape is the common sequential access storage device.
Magnetic tape is also called magnetic tape. These are considered very safe and cheap means of backing up old files. Magnetic tape is a plastic tape half inch or 12.7 mm wide and hundreds and thousands of feet long, which is wrapped on a spool. On one of its surfaces is a thin layer of a magnetic material.The data is written on this layer by making a magnetic mark. Magnetic tape is very slow, as it is a sequential medium. This means that the work of writing or reading data is done sequentially from one end to the other. We cannot start writing/reading from the middle. The work of reading and writing data on the magnetic tape is done by the tape drive. Its capacity ranges from 40 megabytes to 100 megabytes.
■ Direct Access Device
A direct - access storage device ( DASD ) is another name for secondary storage devices that store data in discrete locations with a unique address , such as hard disk drives , optical drives and most magnetic storage devices . It is a technology and term coined for storage devices that IBM developed for use with mainframe computers and some microcomputers. These developed into the modern hard disk and its variants like the optical disk, which today we would simply secondary storage.
Types of Direct Access Device
Magnetic Disk
Optical Disk
Memory Storage Device
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.
Types of Magnetic Disk
Floppy Disk
Hard Disk
*👉 Floppy Disk
* 👉 Hard Disk
OPTICAL DISK
Originally developed in the late 1960s , the
first optical disc , created by " James T.
Russell " , stored data as micron - wide dots
of light and dark . Russell's optical
storage system used a powerful backlight
to read the dots through a transparent
sheet of material on which the dots were
encoded. In later optical disc systems, a
laser read the dots and the data was
converted to an electrical signal. Then the
data was converted to audio or visual
TYPES OF OPTICAL DISK
- 👉 HVD
■ HVD (Hosted Virtual Desktop)
A hosted virtual desktop ( HVD ) is a user
interface that connects to applications and
data that are stored on a cloud provider's
servers rather than on the user's computer
or the corporate network. An HVD is
sometimes referred to as a cloud - hosted
virtual desktop .
HVD is an optical disc technology
developed between April 2004 and mid -
2008 that can store up to several terabytes
of data on an optical disc 10 cm or 12 cm
in diameter .
The company responsible for HVD went
bankrupt in 2010 , and the product was
not launched
Memory Storage Device
It is divide into two parts
USB Flash Drive (Pendrive)
Memory Card (Memory Stick)
■ USB (USB FLASH DRIVE )
A USB flash drive may also be known as a
flash drive or USB drive. A USB flash
drive is a device used to store data, Most
USB flash drives are removable and
rewritable. Physically, they are small,
durable and reliable. The larger their
storage space, the faster they operate. They
derive the power to operate from the device
to which they are connected (typically a
computer) via the USB port. USB flash
drives can store more data and also
transfer it at a faster rate. It is mainly used
to transfer audio, video and data files
from the hard drive of a computer to
another computer. A USB flash drive
consists of a USB connector, which is well
protected and electrically insulated inside a
plastic or rubber case. A small printed
circuit board with surface-mounted
integrated circuits are found within the
device's casing. The main components of
the USB flash drive are: -
Standard USB plug- This connects the flash
drive to a device.
USB mass storage controller- This is a
microcontroller for the USB. It has a small
Flash memory chip - The data is stored in
this.
Crystal oscillator- The data output is
controlled by this component.
■ Memory Card (Memory Stick)
A memory stick is a type of memory card.
This is a USB based memory. Its size is 50.0
x 21.5 x 2.8 mm. Its storage capacity
ranges from 4 megabytes to 256
gigabytes.
Read More :
What is ROM (Read Only Memory) ? & Types of ROM.
Output device and his types define and
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