what is a negative 17 in hexadecimal value

Question

I am a little bit confused in converting -17 into hex. I know that 17 in hex is 11h but answer is in weird form. -17= 17=11h

Answer is 0ffefh. I don't understand how this is done. can anyone show me the steps thanks.

Invert all the bits, then add one. Alternatively, you can first subtract one, then invert all the bits. — harold, Oct 10 '13 at 18:45
You have 11h, so 0000 0000 0001 0001, complement is 1111 1111 1110 1110, add one to get the result you observe — harold, Oct 10 '13 at 18:51
The concept is explained here http://en.wikipedia.org/wiki/Two's_complement#Why_it_works — janos, Oct 10 '13 at 19:06
negative 17 in **twos complement** is something else people have described — Andyz Smith, Oct 10 '13 at 19:19
1Ah = 0000 0000 0001 0010 = 1111 1111 1110 1110 =ffee i am getting wrong result. correct answer is. 0ffffffe6h — ngoche, Oct 10 '13 at 19:55
yea rite..can you explain me how you did it. I was thinking like each hexadecimal value is four bits. 1 = 0001 and A = 0010 i am justing adding zeros in front of hexadecimal characters but thats wrong. Could you explain it pls.. thanks — ngoche, Oct 10 '13 at 20:15
This question appears to be off-topic because it is suited for [math.se] — hjpotter92, Oct 12 '13 at 20:56

score 0 · Answer 1 · answered Oct 12 '13 at 20:54

I don't think the question has anything to do with masm. Just a little dealing with binary numbers.

Since, you've already arrived at 17 = 11H, let's proceed from there. Following 2's complement scheme/representation, 11H is 0001 0001B (just taking one byte). Since the first 8 bits are all 0s, they'll result in FF after we're done.

0001 0001B give you on complementing every bit -> 1110 1110B. Adding one to this result will yield: 1110 1111B which in hexadecimal is EF.

Thus, the 2 byte representation becomes 0xFFEFH

what is a negative 17 in hexadecimal value

1 Answers1