Write VHDL code that gives a behavioral description of a

Chapter 10, Problem 10.21

(choose chapter or problem)

Write VHDL code that gives a behavioral description of a circuit that converts the representation of decimal digits in BCD to the representation using the 2-4-2-1 weighted code, as follows:

                   

For the six input combinations that do not represent valid BCD digits, the circuit output should be “XXXX”. Make the inputs and outputs of type std_logic.

(a) Write the code using the when else assignment statement.

(b) Use the VHDL simulator to verify the code of part (a) for the inputs x = 0011, 0100, 1001, and 1010.

(c) Write the code using the with select when assignment statement.

(d) Use the VHDL simulator to verify the code of part (c) for the inputs x = 0100, 0101, 1001, and 1010.