Differences between primary and secondary memory

Differences between primary and secondary memory

Primary storage devicesSecondary storage devices
1These devices are temporary.These devices are permanent.
2These devices are expensive.These devices are cheaper.
3These devices are faster, therefore expensive.These devices connect via cables and are slow, therefore cheaper.
4These devices have less storage capacity.These devices have high storage capacity.
5These devices refer to RAM, ROM etc.These devices refer to FDD, HDD etc.

(a) BIT (Binary digit): It is the smallest possible unit of information. It can be either 0 or 1.

(b) NIBBLE: Four bits form one nibble

(c) BYTE: It is a unit of information consisting of fixed number of bits. It is a combination of 8 bits

(d) CHARACTER: It is represented by one byte. It can be a letter, digit, punctuation mark or special characters.

(e) WORD: The combination of 2 bytes or 4 bytes or 8 bytes is a word.


The data measurement

8 bits – 1 byte

1024 bytes – 1 kilobyte (KB)

1024 KB – 1 Mega Byte (MB)

1024 MB – 1 Giga Byte (GB)

1024 GB – 1 Tetra Byte (TB)

The teacher summarizes the lesson and allows student to ask questions to clear doubts.

Assessment :

1.       Convert 144mb to byte


Make a research online about secondary storage devices and uses


See also

Types of Secondary Storage

Memory Unit

Central Processing Unit



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