Bits and Bytes

https://web.stanford.edu/class/cs101/bits-bytes.html

Bit

• a “bit” is atomic: the smallest unit of storage
• A bit stores just a 0 or 1

Byte

Group 8 bits together to make 1 byte

• e.g. 0 1 0 1 1 0 1 0
• One byte can store one character, e.g. ‘A’ or ‘x’ or ‘$’

Bytes and Characters - ASCII Code

• ASCII is an encoding representing each typed character by a number
• Each number is stored in one byte (so the number is in 0..255)
• A is 65
• B is 66
• a is 96
• space is 32
• “Unicode” is an encoding for mandarin, greek, arabic, etc. languages, typically 2-bytes per “character”

https://www.asciitable.com/

Typing, Bytes, and You

• Each letter is stored in a byte, as below
• 100 typed letters takes up 100 bytes
• When you send, say, a text message, the numbers are sent
• Text is quite compact, using few bytes, compared to images etc.
  

Numeral systems conversion table

Decimal	Binary	Octal	Hexadecimal
0	0000	0	0
1	0001	1	1
2	0010	2	2
3	0011	3	3
4	0100	4	4
5	0101	5	5
6	0110	6	6
7	0111	7	7
8	1000	10	8
9	1001	11	9
10	1010	12	A
11	1011	13	B
12	1100	14	C
13	1101	15	D
14	1110	16	E
15	1111	17	F

HEX，英文全称 Hexadecimal system，表示十六进制。

DEC，英文全称 Decimal system，表示十进制。

OCT，英文全称 Octal system，表示八进制。

BIN，英文全称 Binary system，表示二进制。