Numeric and Character Encodings

A computer can only store and manipulate 0’s and 1’s .  All data that is passed through the system must be represented as 0’s and 1’s.

A bit can store a 0 or a 1.

Given n bits we can represent 2n different values.

A byte is a sequence of 8 bits.

A byte can hold 256 distinct values: from 00000000 to 11111111.

Representing Unsigned Decimal Values

  • Count to 20 in binary

Numeric Conversions

  • Binary – Decimal
  • Binary – Hexadecimal

Ascii Code

  • ASCII = American Standard Code for Information Interchange
  • Created by IANA
  • Characters in .txt file stored as single bytes.


  • The most recent version of Unicode contains 136,755 different characters for 139 scripts.
  • Unicode uses up to 4 bytes per character.
  • The first 127 Unicode characters are the ASCII characters.


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