## PHYS345 Electricity and Electronics

**Hint for S9.3**
Refer to your notes from our recent class and model after the proof of DeMorgan's first
theorem that was presented.

**Hint for D9.20**

This is the gate combination constructed directly from the Boolean expression.

**Hint for S9.4**

Refer to your class notes on our discussion of segment a.
Also, warm up on the Karnaugh map started for the simpler gate combination for segment c.

**Hint for P9.18**

Construct a truth table with three inputs, A, F, and B_{i} and two outputs,
D and B_{o}.

Think back to elementary subtraction facts:

A=1, F=1, B_{i}=0: With no borrow input, 1-1=0 and no borrow output. Right?

A=0, F=1, B_{i}=0: With no borrow input, 0-1=1 with the borrow output set.

A=1, F=0, B_{i}=1: With the borrow input set, 1-0-1=0 with no borrow output.

Determine the rest of the truth table entries.

Convert to two Karnaugh maps, one for each output. Follow the textbook's example for
the full adder.

"http://www.physics.udel.edu/~watson/phys345/protected/exercises/hints/1029.html"

Last updated Oct. 30, 1998.

Copyright George Watson, Univ. of Delaware, 1998.