# binary questions

Need Help plsDesign the following digital circuits using AND, OR and NOT gates:

a) A binary addtition- substraction circuit that adds or subtracts two 4 bit binary numbers. The circuit has a selection bit that controls whether addition or substraction is to be performed.

b) Draw a combinational circuit that convverts a single hexadecimal number to an equivalent BCD (binary coded decimal)number.

c) A 2 bit counter that counts till 2 that is the counting states are: 00,01,10,00,01,10,00.. .. .. etc

thanks

• : Need Help plsDesign the following digital circuits using AND, OR and NOT gates:
:
: a) A binary addtition- substraction circuit that adds or subtracts two 4 bit binary numbers. The circuit has a selection bit that controls whether addition or substraction is to be performed.
:
:
:
: b) Draw a combinational circuit that convverts a single hexadecimal number to an equivalent BCD (binary coded decimal)number.
:
:
:
: c) A 2 bit counter that counts till 2 that is the counting states are: 00,01,10,00,01,10,00.. .. .. etc
:
: thanks
:
:
:
:

For a)

1. Combine 2 half-adder's to make a 1 bit adder
Use this equation to do a half-adder.

((not (A) && ) A && || ((not (B) && A))

Your A && B is the carry over bit, || is the output result.

To do a 4 bit minus you need to include a inverter going to each of your adders and the one carry in.

I'm a little fuzzy on these so check the equation for truth. The selector switch is a given once you construct your circuit.