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March 3rd, 2013, 07:10 AM  #1 
Member Joined: Sep 2012 Posts: 69 Thanks: 0  Signed hexadecimal computation!
Hello, I have questions about signed number representation in computer. It is about the computation of two hexadecimal number. Lets say there are two hexadecimal numbers and . How do I compute this?? What I know is that I have to convert these two hex into binary and the hex that subtract from another, I have to convert that binary into negative binary and add them up. So will be converted into binary as this.. 8bits And will be . If I convert second number into negative by using two's complement, it will be . If I add them up, I get the result. is this correct?? I think I heard that I have to throw the carry out... so the result becomes . 
March 3rd, 2013, 12:43 PM  #2 
Global Moderator Joined: May 2007 Posts: 6,805 Thanks: 716  Re: Signed hexadecimal computation!
Your final result is correct. You can check it by ordinary subtraction, FF  7F = 80.

March 3rd, 2013, 01:40 PM  #3 
Member Joined: Sep 2012 Posts: 69 Thanks: 0  Re: Signed hexadecimal computation!
so I have throw the carry out right?? Thanks 
March 4th, 2013, 02:59 PM  #4  
Global Moderator Joined: May 2007 Posts: 6,805 Thanks: 716  Re: Signed hexadecimal computation! Quote:
 

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computation, hexadecimal, signed 
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