Bits and Bytes

Extract from the book 'Digital Technology'

The alphabet is a collection of 26 basic symbols that are placed in sequence to create words for communication between humans.  Computers communicate in a similar manner using a stream of the two binary symbols 1 and 0 to create words or represent images and sounds. Each symbol in the stream is called a bit.

A cluster of eight bits is called a byte, for example 10011001. A cluster of 16 bits is called a word, for example 1010100110101101. The most commonly used bit stream cluster is eight bits, which is called a byte.

When computers first started manipulating and storing information a standard was devised for converting text characters into binary strings.

ASCII Characters

The ASCII chart, developed from the original language used on teleprinters, is a set of codes that was introduced by the American Standards Association to represent the alphabet in computers.

ASCII is the abbreviation for American Standard Code for Information Interchange.

Each character of the alphabet is assigned a number. For example, the letter ‘A’ is allocated the number 65 in decimal or 0100 0001 in binary code. ‘B’ is allocated 66 or 0100 0010 and so on. The lowercase ‘a’ is assigned a different number to its uppercase equivalent, namely decimal 97 or binary 0110 0001.

When alphanumeric characters are typed on a keyboard they are translated into a sequence of ‘0’s and ‘1’s. When the character ‘A’ on the keyboard is pressed it is converted into the string 0110 0001.

An 8-bit processor converts a letter that starts with ‘Dear Sir’ to the binary sequence:

010001000110010101100001011100100010000001010011011010010111001000101100

There are various parity checks carried out by the computer to ensure that the validity of the data string is correct, however, the basic translation of the binary string above is as follows:

Each alphanumeric character is converted to a binary string of 8 bits (byte).

Extract from the book 'Digital Technology'

• Next >