Digital-Grand Test -Q5

+1 vote

We know what a full-adder and full-subtractor is. Now consider a 1-bit full adder/subtractor. The two input bits a and b are to be operated on, under the control of a signal k (k=0 for addition, k=1 for subtraction). Another input c_{in} is for either the carry or borrow from the lower bit. The outputs include the result r(sum or difference) and c_{out} for carry or borrow to the next higher bit. 

This 4-input 2-output circuit is implemented using logic gates. The two outputs r( k,a,b,c_{in} ), c_{out}( k,a,b,c_{in} )  are functions of the four inputs k,a,b,c_{in}. The number of prime implicants of r, number of essential prime implicants of r, number of prime implicants of c_{out}, and number of essential prime implicants of c_{out}, respectively, are P,Q,R,S. Then P+Q+R+S is ____?

asked Jun 10 in Digital by gbeditor (44,490 points)
reshown Jun 12 by gbeditor

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r has 4 PI and all these four PI are EPI.

Cout has 5 PI and 5 EPI.

So, total 18.

answered Jun 25 by deepak-gatebook (112,390 points)