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Binary Numbers

It's time to take a look at the binary number system!

Digital electronic devices like the PICmicro microcontroller chip can't cope with the decimal number system (0, 1, 2, ..9 etc.). Instead, they use the binary system. This uses only two numbers 0 and 1. For the PICmicro chip, a number 1 could be a high voltage signal (such as 5V,) while a number 0 could be a low voltage, like 0V.

The table shows how the two systems compare.

Decimal number	Same number in binary
0	0
1	1
2	10
3	11
4	100
5	101
6	110
7	111
8	1000
9	1001
10	1010

With the decimal system, there are ten number figures - 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9. When we get to the last of these figures - 9 - we start again with 0, but we add another number in front of it, e.g. 8, 9, 10 and 18, 19, 20 and so on. When we reach 99, we turn both of these numbers back to 0's and add a 1 in front of them, to make 100.

In binary, the same thing happens, but a lot more often, because there are only two number figures - 0 and 1.
Counting up, we start with 0, then 1, then we go back to 0 and add a '1' in front to make 10 (but this isn't ten - it's two) next comes 11 (three) and then we have to go back and start again with 0's and add a '1' in front, to give 100 (four) and so on.