Exercise on Digital Logic


Examine the following logic circuit.

a)   Identify the following logic gates.

b)  Construct the truth table for the logic circuit shown above.

c)   Represent the circuit above as a logical expression.


An embedded system monitoring a room consists of the following:

      A door sensor D which is ON when the door is closed and OFF when the door is open.

      A motion sensor M which is ON when there is someone inside the room and OFF when the room is empty.

      A temperature sensor T which is ON if the temperature is too high and OFF if the temperature is normal.

The output of a system is a sound alarm A which is activated (ON) if one of the following conditions occurs.

      The door is open when there is no one in the room.

      The temperature inside the room is too high.

a)  Draw the logic diagram of this system.

b)  Write the logical expression that represents this system.

c)   Construct the truth table of the system.