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Read-only Memory (ROM)
ROM is a non-volatile memory. The data and information stored in

this memory do not lose even if the computer is switched off. It is
permanent in nature. There are three types of ROM:
Programmable Read-only Memory (PROM) ROM

Erasable Programmable Read-only Memory (EPROM)
Electrically Erasable Programmable Read-only Memory (EEPROM)

Tick ( ) if you know this.

▶ Data and information on a computer is stored in the form of 0s and 1s, called binary digits.
▶ 1 TeraByte is equal to 1024 GigaBytes.

SECONDARY MEMORY
Secondary memory is the external memory of the computer that can store large

amounts of data permanently. It is not directly accessed by the CPU. It is cheaper in
comparison to primary memory. Secondary memory devices are also called secondary

storage devices.

Hard Disk

Hard disk is the main secondary storage device, used to store data
and information. It is fixed inside the CPU cabinet. It consists of one or
more magnetic disks which is used to store and restore digital

information for usage. Hard Disk

Compact Disc (CD)

CDs are circular in shape. It can store a large amount of data and can be
carried from one place to another easily. It can store up to 700MB of data.

CD There are three types of CDs:

Compact Disc-Read Only Memory (CD-ROM): It contains data that has been written
at the time of manufacturing and cannot be modified or erased.

Compact Disc-Recordable (CD-R): It allows only one-time recording. Data written once
cannot be erased.

Compact Disc-Rewritable (CD-RW): It allows multi-reading. Data written on it can be

erased or rewritten.

10 Computer Science (V5.0)-IV