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Electronics and Communication Engineering - Digital Electronics - Discussion

Discussion Forum : Digital Electronics - Section 1 (Q.No. 22)
Digital Electronics
22.
The greatest negative number which can be stored is 8 bit computer using 2's complement arithmetic is
- 256
- 128
- 255
- 127
Answer: Option
Explanation:

The largest negative number is 1000 0000 = -128.

Discussion:
16 comments Page 1 of 2.
Dhanya said:   7 years ago
For 2's compliment representation, Range is {-2^(n-1) ) to +(2^(n -1))-1}.
Here n=8 ,then { (-2^(8-1)) to +(2^(8-1))-1}.
-2^7 to +(2^7)-1.
-128 to +127.

So, the greatest negative number in 2'compliment representation is - 128.
(2)
Sumesh said:   7 years ago
+128 = 10000000,
-128 =2's compliment of 10000000,
=1's compliment of 10000000 +1,
= 01111111 +1,
=1000000.
(1)
Dhanya said:   7 years ago
-128 in 2's compliment form = 2's compliment of + 128.
+128 in binary form=01111111.
2's compliment of 01111111=10000001.
(1)
Tshering Dorji said:   5 years ago
Then, what is the way to find the largest negative and positive number for 1s complement and signed number?

Please, anyone, tell me.
(1)
Geetha adainjan said:   1 decade ago
Why 1111 1111= -255 not came here? Please clarify it.
Pratik said:   1 decade ago
It is not largest number.
Rekha.v said:   1 decade ago
The greatest negative number which you can represent using N bit (of course signed) could be -2^(N-1).

So for 8 bit 2^7 = -128.
Rekha.v said:   1 decade ago
The greatest negative number which you can represent using N bit (of course signed) could be -2^(N-1).

So for 8 bit 2^7 = -128.
Sudipta Majumder said:   1 decade ago
Greatest positive number = 01111111.

Taking 2's complement to get greatest negative number that is = 10000001.

Now put the formula and we get = -127.
Sunanda said:   9 years ago
Greatest positive number is 255, right?
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