De Morgan's theorems

Augustus De Morgan was the first who found the link between logic and mathematics.

Fig. 2-8: Logic circuits with the same output

Although the circuits are different but the output, as we can see in the truth table, is equal. Therefore we can write:

De Morgan's First Theorem

Also if we compare the two circuits on the next page we can easily see that the output is the same, although the circuits are different.

(see Fig. 2-9)

Fig. 2-9: Logic circuits with the same output

So we can write:

De Morgan's Second Theorem

HO: How can you connect a NAND gate to get an inverter

Solution:

Figure

HO: How can you connect NAND gates to get an OR gate?

Solution:

Figure