i am having trouble to understand complement.. - Electronic Circuits Projects Diagrams Free

transgalactic · 2nd May 2008, 07:54 AM

i am having trouble to understand the meaning
of complement 1 and complement 2 of a certain number

after looking a this table:http://s290.photobucket.com/albums/l...t=IMG_8817.jpg

i came to the conclution that the complement 1 and complement 2 of a positive stays the same
but in the case of a negative number
there is a unique transformation for each type
of complement.

how does the complement to 1 and the complement to 2
changes the value of a negative number

and why it doesnt change possitive numbers

Pommie · 2nd May 2008, 08:08 AM

Twos compliment subtracts the number from zero and so the top bit gets set. To obtain a twos compliment number you invert all the bits and add 1 to the result. So, 1 (00000001) gets inverted (11111110) and then incremented (11111111) to get -1. Also, -1 (11111111) gets inverted (00000000) and then incremented to get (00000001) 1.

Ones compliment is the same except you don't do the increment after the inversion. So, -1 = 11111110.

In both systems the largest positive number is 127.

Check wikipedia for a longer explanation.

Mike.

transgalactic · 2nd May 2008, 02:28 PM

is it ok???

" Ones complement and twos complement are methods of representing negative numbers. Therefore, they don't affect positive numbers.

To represent a negative number in ones complement, the positive value simply has all its bits inverted. Example: to represent -25 in ones complement, take the binary representation of +25 which is 00011001, then invert the bits: 11100110. Done.

To represent a negative number in twos complement, take the ones complement from the previous example, and add one to it: 11100110 + 00000001 = 11100111
"

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2nd May 2008, 07:54 AM	(permalink)
transgalactic	i am having trouble to understand complement.. i am having trouble to understand the meaning of complement 1 and complement 2 of a certain number after looking a this table:http://s290.photobucket.com/albums/l...t=IMG_8817.jpg i came to the conclution that the complement 1 and complement 2 of a positive stays the same but in the case of a negative number there is a unique transformation for each type of complement. how does the complement to 1 and the complement to 2 changes the value of a negative number and why it doesnt change possitive numbers

2nd May 2008, 08:08 AM	(permalink)
Pommie	Twos compliment subtracts the number from zero and so the top bit gets set. To obtain a twos compliment number you invert all the bits and add 1 to the result. So, 1 (00000001) gets inverted (11111110) and then incremented (11111111) to get -1. Also, -1 (11111111) gets inverted (00000000) and then incremented to get (00000001) 1. Ones compliment is the same except you don't do the increment after the inversion. So, -1 = 11111110. In both systems the largest positive number is 127. Check wikipedia for a longer explanation. Mike.

2nd May 2008, 02:28 PM	(permalink)
transgalactic	i was told some thing else.. is it ok??? " Ones complement and twos complement are methods of representing negative numbers. Therefore, they don't affect positive numbers. To represent a negative number in ones complement, the positive value simply has all its bits inverted. Example: to represent -25 in ones complement, take the binary representation of +25 which is 00011001, then invert the bits: 11100110. Done. To represent a negative number in twos complement, take the ones complement from the previous example, and add one to it: 11100110 + 00000001 = 11100111 "