SS 2 Computer Studies/Information Technology (1st, 2nd & 3rd Term) Computer Studies/ICT/IT (All Classes) SS 1 Computer Studies (1st, 2nd & 3rd Term)

Differences between primary and secondary memory

Differences between primary and secondary memory

Primary storage devices Secondary storage devices
1 These devices are temporary. These devices are permanent.
2 These devices are expensive. These devices are cheaper.
3 These devices are faster, therefore expensive. These devices connect via cables and are slow, therefore cheaper.
4 These devices have less storage capacity. These devices have high storage capacity.
5 These 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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