SS2 WEEK: 5 TOPIC: MEMORY UNIT II

CONTENT 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 is as follows: 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)