Bits, bytes and words

Overview

Term word as it applies to a processor, term nibble and why a bit on its own carries very little meaning.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   What is a bit?

   Model answer

   A bit is the smallest unit of data a computer stores, holding either 0 or 1. The word bit is a contraction of binary digit.

2. 2

   How many bits make one byte?

   Model answer

   One byte is a group of eight bits. A byte is the smallest block of storage that most systems address individually.

3. 3

   Define the term word as it applies to a processor.

   Model answer

   A word is the number of bits a processor handles as a single unit. Word length is set by the width of the registers and the data bus.

4. 4

   Why does a larger word length usually give better performance?

   Model answer

   A larger word length moves more bits between memory and the processor in one transfer. Larger words also allow a wider range of numbers to be held in one register.

5. 5

   How many different values can be represented by a group of n bits?

   Model answer

   A group of n bits gives 2ⁿ different bit patterns. Eight bits therefore give 256 patterns, from 00000000 to 11111111.

6. 6

   State the largest unsigned denary value that can be held in one byte.

   Model answer

   The largest unsigned value in one byte is 255. The bit pattern 11111111 gives that value, which is 2⁸ − 1.

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