Connect the outputs of 4 XOR gates to B1-B4. Connect one of each XOR's gate input to C1. The other four inputs on the XOR gates (one input per gate) are your new inputs for B1-B4. When you apply high logic to Cin the circuit will subtract A-B , when you apply low logic to Cin the circuit will add A+B.
I just drew this up real quickly in Photoshop. So the objective is to use the IC and four inverters to create a subtractor circuit that'll do the following operation:
A4 A3 A2 A1 - B4 B3 B2 B1
So would I just invert all the B's on the circuit?
Ok then. Connect 4 NOT gates on the B inputs and apply a high logic to Cin input.Is there a way to just do it with inverters? The worksheet we were given only says "Use the IC below and 4 inverters to subtract..."
I was trying to figure out how on earth to do the 2's complement method with this, are using the XOR gates the only way?
yes the carry in is the 1 we add n the 2's complement.So the carry-in high is basically the 1 that is added when a 2's complement is performed?
I believe I understand now, thanks a bunch to the both of you! Hopefully I'll be ready for the exam come tomorrow.
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by Jake Hertz
by Jake Hertz
by Kate Smith