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Adder and substrate with signed number
- Thread starter Ahahah
- Start date
The basic circuits are called a Half Adder and a Full Adder.
The Half-Adder takes two input bits and produces a sum and a carry. So it is a Boolean function with two inputs and two outputs.
The Full-Adder takes three inputs, a carry in and two input bits. It produces a sum and a carry. So it is a Boolean function with three inputs and two outputs.
Once you have those two function blocks, the rest is done with input multiplexers.
The Half-Adder takes two input bits and produces a sum and a carry. So it is a Boolean function with two inputs and two outputs.
The Full-Adder takes three inputs, a carry in and two input bits. It produces a sum and a carry. So it is a Boolean function with three inputs and two outputs.
Once you have those two function blocks, the rest is done with input multiplexers.
I tried but it give wrong answer in -3 minus -1 and -1 minus -3
Show me.
Sorry ,I don't have laptop now
But I tried to think it with comparator
If it possible to make it on logisim as I have it as assignment and deadline is near
Feel free to help me when you have free time
I don't have logisim so I can't help you with that.
So, with 3 bits you can represent 8 different numbers in the range [-4,...3]
So subtraction is the same as adding the two's complement
-3 minus -1 is the same operation as -3 + 1 = -2, and
-1 minus -3 is the same operation as -1 + 3 = +2
Do you agree with that or is there some other result you can share?
I shouls also point out that adding the twos complement is the same as adding the 1's complement and adding 1.
Does that give you any clues about what you should do?
So, with 3 bits you can represent 8 different numbers in the range [-4,...3]
So subtraction is the same as adding the two's complement
-3 minus -1 is the same operation as -3 + 1 = -2, and
-1 minus -3 is the same operation as -1 + 3 = +2
Do you agree with that or is there some other result you can share?
I shouls also point out that adding the twos complement is the same as adding the 1's complement and adding 1.
Does that give you any clues about what you should do?
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