Student "edition" found at {csi dot journalspace dot com}.

Maybe I shouldn't have started this blog now, not with everything that's been going on.

In the last meeting of my Computer Systems Organization lecture class for the fifth week of the third term, I discussed using alternative gates for completing logical Boolean circuits that we have already taken up.

I introduced the NAND, the NOR and the XOR gates which are short for Not-And, Not-Or and Exclusive Or.

The first and second I only demonstrated as having the output of the “And” and “Or” gates inverted.

To explain the logic behind the XOR gate I had to give concrete everyday examples.

In the regular “Or” gate, it is like someone who had two preferences for a person applying for a job, such as a Master’s degree OR ten years’ industry experience.

But it an applicant comes along who has both, that person would also be hired. That’s where the “1 or 1 equals 1” comes in.

Another example is that game show format diaper TV commercial where a housewife is being asked to choose between economy and quality, and she wants both.

Sometimes though, there are situations where choosing only one of the options is correct or possible, but not both.

For this one I gave the instance of a person having just enough money to buy one thing for lunch, such as a burger or a salad, but he cannot eat both.

Another situation is in one of those standard Korean TV series where a girl can only choose one of the two guys in the end – but not both.

From there we went to using the NAND and NOR, which according to the book are easier and cheaper to manufacture, to simulate the “Not”, “And” and “Or” gates.

To round out the period, I gave them two functions they were supposed to get regular truth tables and circuits to, and change the gates to either all “NOR” gates or all “NAND” gates.

Session 989 can’t have both.