made easy cbt

Question

Comments

answer given is -128 and i am getting -127.

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Would you please work out on how you've got -127. Also I found a somewhat similar question posted here earlier. In d link below. If you work out on some steps then it'll be way better. Yeah!!!

https://gateoverflow.in/1767/gate2014-1_9

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-128 is correct answer as  in 8 bit we have 10000000 so here sign bit is 1 so just take the magnitude as this number is in 2's complement form 

Answer 1

Size of instruction = 24 bit.

Size of register = 32 bit

No.of instructions = 49

Instruction contain opcode, R1, R2, Immediate operand

Bits for opcode= 6 bit (For representing 49)

Bits for R1 = 5 bit (For representing 32)

Bits for R2 = 5 bit (For representing 32)

Bits left for Immediate operand = 24-(6+5+5) = 8 bit 

It is given immediate operand is signed integer( by default 2's complement)

Range of 2's complement in 8 bit = -128 to 127 (Minimum is 128)

Hence -128 is the answer.

Comments

You are taking about signed magnitude representation which is not there

Floating point signed integers have three representation.

1.Signed magnitude

2. 1's complement

3. 2's complement

And by default no. is in 2's complement(if not given)

Now I think it's clear to you

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In short it's gotta be like tat d instruction code value in any case shud  be rounded? Isn't it?

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Ofcourse we have to do..