Binary addition, subtraction, overflow and two’s complement
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The teaching part (1 min) is free to watch. A free account opens the whole lecture: 2 worked examples, 5 practice questions, 2 real past-paper questions with the answers explained, the mistakes that lose marks, the full-marks tip, a one-card summary and a quick quiz.
What this lecture covers
- Adding in columns, as at school
- The four rules of binary addition
Read the transcript of the teaching part
Adding in columns, as at school
You add denary numbers in columns, carrying when a column passes nine. Binary works the same way, but you carry when a column passes one. And once the answer needs more bits than the register has, you get overflow.
The four rules of binary addition
Zero plus zero is zero. Zero plus one is one. One plus one is zero, carry one. One plus one plus a carry of one is one, carry one.
Chapter 1: Information representation
- Binary, denary, hexadecimal, BCD and prefixes 6 min
- Binary addition, subtraction, overflow and two’s complement 7 min
- Character sets, run-length encoding and compression 6 min
- Bitmap images, vector graphics and sound 6 min
Also for A Level Computer Science 9618
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