hw23Hints - Problem 6. Your circuit must operate in two...

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//home/vdimitrov/5860/4f8b1ff018827231e4bb26974c96b255b2ac87c5.doc Hints for HW Set 23 Problem 4. The Full Adder adds three bits. Add the first two using a Half Adder, then the add the result to the third bit using a second Half Adder. When does the 3-bit sum produce a carry? Problem 5. Consider the Full Adder by itself. Shown below is the circuit realization that works for active- High inputs and outputs. Also shown are active-Low inputs and outputs connected to the circuit. (a) Write the logic expressions for F, G, each in terms of p, q, r. (b) Evaluate your expressions in a Truth Table. (c) Does your F function agree with the s output of a Full Adder (with inputs p, q, r) ? (d) Does your G function agree with the c output of a Full Adder (with inputs p, q, r) ? (e) What do you conclude about the 4-bit adder with active-Low inputs?
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Unformatted text preview: Problem 6. Your circuit must operate in two different modes, determined by the value of S. When S = 0, the circuit output is ( A plus B ); When S = 1, the output is ( A - B ) = ( A plus B ' plus 1 ). Organize your circuit as shown below. Design the circuit module C1 so that Output bits = Corresponding input bits when S = 0. Output bits = The negation of the corresponding input bits when S = 1. [ To further simplify this module, consider only one input bit b. The output is equal to b when S = 0, is equal to b' when S = 1. Design this circuit, then use three copies of it for the other bits.] Design the module C2 so that Error is asserted properly for the addition or subtraction operation: Error equals co when S = 0, Error equals co ' when S = 1. Finally, decide how to connect the ci input....
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hw23Hints - Problem 6. Your circuit must operate in two...

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