Sign & Modulus

(integer representation)

 

This is a method to represent negative numbers. The leading bit indicates “+” or “-“

 

“0” indicates “+” or positive

“1” indicates “-“ or negative

 

Four bit representation gives us the numbers 7 to -7

 

7		1	1	1				7		0	1	1	1
6		1	1	0				6		0	1	1	0
5		1	0	1				5		0	1	0	1
4		1	1	0				4		0	1	1	0
3		0	1	1				3		0	0	1	1
2		0	1	0				2		0	0	1	0
1		0	0	1				1		0	0	0	1
0		0	0	0				0		0	0	0	0	also 1000
								-1		1	0	0	1
								-2		1	0	1	0
								-3		1	0	1	1
								-4		1	1	0	0
								-5		1	1	0	1
								-6		1	1	1	0
								-7		1	1	1	1

 

Eight bit representation extends the maximum and minimum numbers

The highest positive number is 0111 1111 or 127

The lowest negative number is 1111 1111 or -127

 

 

	8			0	0	0	0		1	0	0	0
	7			0	0	0	0		0	1	1	1
	6
	5
	4
	3
	2
	1
	0			0	0	0	0		0	0	0	0	Also 1000 0000
	-1
	-2
	-3			1	0	0	0		0	0	1	1
	-4
	-5
	-6
	-7			1	0	0	0		0	1	1	1
	-8			1	0	0	0		1	0	0	0