Why operators model combinational logic behavior in VHDL - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to assign the output as the AND of inputs A and B.

VHDL

output_signal <= input_a [1] input_b;

Drag options to blanks, or click blank then click option'

Anand

Bor

Cxor

Dand

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'or' instead of 'and' changes the logic behavior.

The and operator models combinational AND logic between two signals.

2fill in blank

medium

Complete the code to assign output as the OR of inputs A and B.

VHDL

output_signal <= input_a [1] input_b;

Drag options to blanks, or click blank then click option'

Aor

Bnand

Cxor

Dand

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'and' instead of 'or' changes the logic behavior.

The or operator models combinational OR logic between two signals.

3fill in blank

hard

Fix the error in the code to correctly assign output as XOR of inputs A and B.

VHDL

output_signal <= input_a [1] input_b;

Drag options to blanks, or click blank then click option'

Axor

Bnand

Cor

Dand

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'or' or 'and' instead of 'xor' changes the logic behavior.

The xor operator models combinational exclusive OR logic between two signals.

4fill in blank

hard

Fill both blanks to create a combinational expression that outputs 1 only when both inputs are 1 and then inverts the result.

VHDL

output_signal <= [2] (input_a [1] input_b);

Drag options to blanks, or click blank then click option'

Aand

Bor

Cnot

Dxor

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'or' instead of 'and' changes the logic.

The expression uses and to combine inputs, then not to invert the result, modeling NAND logic.

5fill in blank

hard

Fill both blanks to create a combinational expression that outputs 1 when input_a is 1, input_b is 0, and input_c is 1.

VHDL

output_signal <= (input_a [1] (not input_b)) [2] input_c;

Drag options to blanks, or click blank then click option'

Aand

Bor

Cxor

Dnand

Attempts:

3 left

💡 Hint

Common Mistakes

Using OR or XOR changes the logic behavior.

The expression uses and operators to combine conditions, modeling combinational logic that outputs 1 only when input_a and input_c are 1 and input_b is 0.