two's complement numbers



A format for number representation in which negative numbers are

	indicated by the to bit effectively having a negative value




	-32	16	8	4	2	1


	1	1	1	1	1	1		-1

	0	0	0	0	0	1		1

	1	1	1	1	0	0		-4

	0	0	0	1	1	0		6



Positive values are the same (as normal binary numbers) as long as

	the number is not so large that it would involve the top

	bit being set


Zero is all zero bits

-1 is all bits set to 1

-2, -3 etc. as according to the pattern above


Normal algorithms for addition, subtraction etc. tend to produce these

	numbers automatically without changing the algorithm


Range is -2^(n-1) to +2^(n-1)-1


Extra blocks can be added to the left side without altering the number

	if all set to 0 or 1 as appropriate



