Binary Number System

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Unsigned binary

Binary-Decimal Conversions

This video contains lots of examples of converting binary numbers to decimal numbers, and vice versa. A good revision guide.

Updated: 2018-02-17

Unsigned binary arithmetic

Binary Addition & Overflow

Another excellent video from ComputerPhile with their usual clear explanations and worked examples. This video recaps binary numbers and then explains how to perform binary addition. It also deals with the potential problem of overflow and how it can be handled.

Updated: 2015-04-29

Signed binary using two’s complement

Why we use Two's Complement

This video explains how to represent negative numbers in binary. It explains why we can't use a simple sign bit to represent positive or negative numbers, and then looks at how one's complement solves this problem. Finally it explained how two's complement works and why it is used. Although the beginning of the video goes into a lot of detail, it is useful to understand exactly why two's complement is needed and used.

Updated: 2015-04-29

Numbers with a fractional part

A-Level appendix unit - PG Online

Floating point numbers, adders, D-type flip flops are covered in this free lesson resource unit from PG Online. The presentations and activities are designed for the AQA AS and A-Level courses, but the content is relevant to other A-Level courses too.

Updated: 2017-10-17

A-Level only content

Rounding errors

Absolute and relative errors

Range and precision

Normalisation of floating point form

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