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Secondary Memory
Secondary memory is permanent in nature
and is not directly accessed by the CPU. It The human brain can hold about
allows users to store data that may be easily 2.5 petabytes of information, equivalent
retrieved. It is cheaper as compared to to a TV show being played for
primary memory. approximately 342 years non stop.
Secondary memory devices are also called
secondary storage devices. They are
categorised into three types: Magnetic disk, Optical disc and Flash drive.
Secondary Memory
Magnetic Disk Optical Disc Flash Drive
Hard Disk CD DVD Blu-ray Disc Pen Drive Memory Card SSD
Magnetic Disk
A device, covered with a magnetic coating is called a magnetic disk. You can record and
erase data on a magnetic disk any number of times.
Hard Disk
The hard disk consists of one or more magnetic disks. Each
disk in the pack has top and bottom surfaces on which data
is recorded using magnetic head. It is permanently fixed in the
system unit. The most important function of the hard disk is to
store program files and data files. Hard disk
Hard disks are available in a variety of sizes with storage capacities as high as 5 TB (Terabyte)
or even more. The CPU can access data stored on a hard disk much faster than other storage
devices.
External hard disks are also available. They are the hard disks that
can be connected to any computer with the help of a USB port. They
offer the convenience of expanding storage capacity without the
need for internal installation and are commonly used for backing up
External hard disk data, transferring files, or increasing storage space on laptops and
desktops.
Data Storage and Memory 9

