OR gate

We can make OR gates from switches and transistors, but we normally buy them packaged in an Integrated Circuit. A QUAD 2-input OR Gate is packaged in a 14 pin IC. A 2-input OR gate means that each gate has an A and B input (some gates have 3). QUAD means there are four gates. This accounts for 4x3=12 pins. The other two pins are for the power supply.

 

                        Australian Standard                                                  Distinctive

    

There are two ways of drawing gates. Many books still use the Distinctive symbols but the Australian Standard should be used.

Use your Logic Test Board to determine the truth table. Remember 1 is ON and 0 is OFF.

When A or B touches + then write 1. When A or B touches gnd then write 0.

TRUTH TABLE

A	B	C
0	0
0	1
1	0
1	1