Questions about digital electronics fundamentals

Thread Starter


Joined Sep 29, 2011
I am currently studying at university. Unfortunately due to illnes I was forced to skip one month and now I fear that I was left behind.

I would really appreciate any pointers about those topics.

Basically, I want to know what kind of rules do I need to learn to solve these problems. Also, if possible, can you show step by step solution of those problems or similar problems so I get some idea what they want me to do there.


Joined Nov 25, 2009
Take a note on the codes below the blue "boxes". These codes represent which Integrated Circuit that box is. For example, 7486 is a 2-input XOR gate. You can google those codes and find out about them. I assume you are familiar with all of the logic gates such as AND, NOR and XOR. Correct me if I 'm wrong.

What you should do is look at the timing diagrams and notice that any vertical line crosses all of the input diagrams (ie. A,B and C in the first question) represents an instance in time.
If a graph is high in that instance then the value of that input is HIGH (or 1). If it lies on the x-axis it's LOW (or 0).
You have to draw the output diagram versus the time, in a manner that shows the output of the gate, throughout the time, given the gate inputs.

Is that clear?