Bits and Bytes Theory

A binary number is either a 0 or a 1 and is known as a 'bit' or

b inary dig it .

However, the CPU cannot deal with just one bit at a time, it is just too small.  It usually deals with 8 bits at a time, which is known as a Byte . 

11100101 is a byte, 10000111 is also a byte, or any other combination you can think of which contains 8 zeros and ones.

Why does all this matter?

We often need to process words, so the computer must be able to store letters and other keyboard characters.  This is done by making up a code.  Each number represents a character.

One common code is A=65, B = 66 and so on.  This is called ASCII code or A merican S tandard C ode for I nformation I nterchange. 

Each ASCII character occupies just one byte.  The eight bit binary code or byte which represents the letter A is

The word JOHN would take 4 bytes of memory to store.

RAM can store millions of bytes.  So of course all that information needs to be accessed by the CPU.  It does this through a method called, 'addressing'.  Every location in RAM has a unique address.

 Each storage location (address) contains a byte which represents data in the form of:

• a number
• a character or string of characters
• a computer instruction
• part of a picture
• the address of a location in store

But remember - all this information is stored as strings of 1s and 0s i.e. binary code