Inside the computer are bits and bytes. To really understand what is going on, you need to know something about bits and bytes.

A bit, for binary digit, can represent two values.

The two values of a bit are often written as 0 and 1.

But you cannot actually see a 0 or 1 inside a computer.

How are the 2 values of a bit represented?

Here are some ways to represent 2 values of a bit.

• low or high voltage level
• low or high light level
• low or high magnetic field
• low or high reflection level

A original standard CD (Compact Disc) can hold 650 MB of data, or about 5 billion bits. Each bit is either a burned hole or not a burned hole at a certain position on the CD that either reflects light or does not reflect light. That is how the 5 billion bits are created and accessed.

A byte is made up of 8 bits.

Question: How many values can a byte represent?

A byte can represent 256 values.

Since each bit can represent 2 values, 8 bits can represent 256 values as follows.

A nibble is half a byte

Yes, the technical term for four bits, or half a byte, is a nibble.

• A group of 4 bits make a nibble that can represent 16 values.
• A hexadecimal digit represents one nibble, or 4 bits.

Computer engineers are often concerned with the upper nibble (upper 4 bits) and lower nibble (lower 4 bits) of a byte.

• A group of 16 bits (i.e., 2 bytes) is called a word or WORD.
• A group of 32 bits is called a dword, for double-word or DWORD.
• A group of 64 bits is called a qword, for quad-word or QWORD.

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