How Data is Held

A base 2 number system represented through the digits 1 and 0.

All data is held using on/ off signals

Computer systems are based on switches, which can only have two states, on or off. Binary numbers use two digits. Binary is high tolerance and robust.

one binary digit 1 or 0

a group of 8 bits

a group of 4 bits

128, 64, 32, 16, 8, 4, 2, 1

Add up the values of all place values where there is a 1

Subtract place values from the denary starting with the highest. When you do this, put a 1 in that place value

A base 16 number system. The digits 0-9 are the same as denary, while the digits 10-15 are A-F alphabetically.

-easy to convert to and from binary -easier to understand than binary

divide the denary number by 16. The quotient goes in the 16s column, the remainder goes in the 1s column.

Split the number into nibbles and write the matching hexa number under each group of 4.

Write 4 bits under each hexa digit

A character set that represents each keyboard character (265 charas) as 8- bit binary codes.

An extended character code sequence. Old ascii files can still be read with unicode.The first 8 bits of unicode are the same as ascii, but it used 16-32 bits so needs more storage space.

• All global alphabets including braille. • Currency, maths, map, and musical symbols • Ancient languages eg. hieroglyphics • Codes for emojis and other pictures • Control and Formatting signs

• the unicode consortium • if you invent a new emoji or code you want to be used, you have to submit it to them . If they agree they will give it a code.

Every make of computer / phone may interpret unicode characters slightly differently , eg apple vs android emojis look different.

(using the example c) 1) ord(“c”) 2) chr(67)

the most significant bit stores the sign ( 0 for + , 1 for - )

The most signigicant bit is a negative value and the rest are positive

it can be used in calculations, whereas sign and magnitude can’t.

flip all the bits, then increment the least significant bit