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+15 votes

The octal representation of an integer is $(342)_8$. If this were to be treated as an eight-bit integer in an $8085$ based computer, its decimal equivalent is

  1. $226$
  2. $-98$
  3. $76$
  4. $-30$
asked in Digital Logic by Veteran (59.6k points)
edited by | 1.7k views

1 Answer

+21 votes
Best answer
$(3\; 4\; 2)_8 = (011 \; 100 \; 010)_2 = (11100010)_2.$

If we treat this as an 8 bit integer, the first bit becomes sign bit and since it is "1", number is negative. 8085 uses 2's complement representation for integers and hence the decimal equivalent will be $-(00011110)_2 = -30.$
answered by Veteran (359k points)
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Sir, why haven't you considered 0 ( 011100010 ) as the sign bit? I calculated the answer as 226.

they said its 8 bit integer
Yes, I missed it. Thanks
@arjun_sin, it is not mentioned anywhere in question, first bit will be signed bit, i am confused here when we consider 1st bit is signed bit and when we ignore 1st bit
In this question they have mentioned 8bit integer in an 8085 therefore we are considering 8 bit from LSB to MSB, if nothing is mentioned then we have to consider it as a +ve number.
can uh tell me meaning of 8085 based computer,

Main thing is we have to take 8 bit from LSB to MSB 

@Arjun @ Arjun

Sir , why we are considering it as signed no?

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