Hexadecimal Revision
ASCII and Unicode
ASCII The ASCII character set is a 7-bit set of codes that allows 128 different characters. That is enough for every upper-case letter, lower-case letter, digit and punctuation mark on most keyboards. ASCII is only used for the English language.
Hexadecimal and character sets
Text and numbers can be encoded in a computer as patterns of binary digits. Hexadecimal is a shortcut for representing binary. ASCII and Unicode are important character sets that are used as standard.
Converting hexadecimal
To convert denary numbers to hex, you need to remember the equivalent binary numbers for the first 16 hex digits.
This table shows each hex digit with the equivalent values in binary and denary
https://rajatcomputing.files.wordpress.com/2013/10/binary-to-decimal-and-hexadecimal-conversion-memorization-chart.jpg
Converting hexadecimal Table
https://www.bbc.com/bitesize/guides/zp73wmn/revision/3
ASCII and Unicode table
https://www.bbc.com/bitesize/guides/zp73wmn/revision/5
Hexadecimal (or hex)
is a base 16 system used to simplify how binary is represented. A hex digit can be any of the following 16 digits: 0 1 2 3 4 5 6 7 8 9 A B C D E F. Each hex digit reflects a 4-bit binary sequence.
This means an 8-bit binary number can be written using only two different hex digits - one hex digit for each nibble (or group of 4-bits). It is much easier to write numbers as hex than to write them as binary numbers.
For example: 11010100 in binary would be D4 in hex FFFF3 in hex would be 11111111111111110011 in binary
Colours
Hex can be used to represent colours on web pages and image-editing programs using the format #RRGGBB (RR = reds, GG = greens, BB = blues). The # symbol indicates that the number has been written in hex format. This system uses two hex digits for each colour, eg #FF6600 pic:https://www.bbc.com/bitesize/guides/zp73wmn/revision/2
Using hexadecimal
Hex codes are used in many areas of computing to simplify binary codes. It is important to note that computers do not use hexadecimal - it is used by humans to shorten binary to a more easily understandable form. Hexadecimal is translated into binary for computer use. Some examples of where hex is used include: colour references assembly language programs error messages
