+ 3

Why 256 ASCII combinations?

I keep hearing about the number 256 thrown about in reference to bytes, ASCII, and/or hexadecimal. What does it mean? Aren't there way more than 256 8-bit combinations?

25th Aug 2019, 3:22 AM
Clavis Janes
Clavis Janes - avatar
5 Answers
+ 14
One bit has two possible values 0 or 1, (2^1=2) Two bits has 2^2= 4 Three 2^3= 8 ... 2^4= 16 ... 2^5= 32 ... 2^6= 64 ... 2^7= 128 And Eight bits has 2^8= 256 Notice how the values double for every bit? You are probably confusing total number of values possible in 8 bits with 32, 64 or even 128 bits. 2^8= 256 # 8 bits 2^16 = 65536 # 16 bits 2^32 = 4.29497*10^9 # 32 bits 2^64 = 1.84467*10^19 # 64 bits
25th Aug 2019, 4:18 AM
Lord Krishna
Lord Krishna - avatar
+ 8
The possible values of 8-bit, or a single byte, would be 0000 0000 0000 0001 0000 0010 ... 1111 1110 1111 1111 This ranges from 0000 0000 (0) to 1111 1111 (255), which is a total of 256 distinct values.
25th Aug 2019, 4:01 AM
Hatsy Rei
Hatsy Rei - avatar
+ 6
Just adding little more to what Hatsy said.... The number of values that a number system can represent is is equal to its base.. Binary has base of 2 so it uses only 0 and 1 bits to represent any number. The number of values we can represent using bits is equal to 2^n where n is number of bits in representation . Ex. using 2 bits we can represent 2^2 =4 values 00 01 10 11 Using 3 bits 2^3=8 000 001 010 011 100 101 110 111 ASCII is 8 bit code system it has 2^8=256 characters. These are enough to represent all alphabets, numbers and special symbols and some functions also.
25th Aug 2019, 4:13 AM
🇮🇳Omkar🕉
🇮🇳Omkar🕉 - avatar
+ 4
Also, ASCII has 128 possible values, not 256. There are a lot more than 256 possible letters in all of the word which is why we use unicode (up to 32 bits per letter) instead of ASCII (7 bits per letter) most of the time!
25th Aug 2019, 7:20 AM
Schindlabua
Schindlabua - avatar
+ 2
Thanks everyone!
25th Aug 2019, 2:56 PM
Clavis Janes
Clavis Janes - avatar