Extra practice questions on digital logic circuits

1. Draw a truth table for function m0 in the circuit shown below.
   

2. Draw a karnaugh map for function sum1 in the circuit shown below, and use it to produce a minimal sum-of-products expression for the function.
   

3. Apply DeMorgan's rules to the OR gates in the circuit below, and draw the resulting circuit (note that one input will need to change to y1' instead of y1).