All things in all posts will help you visualize about the way that computers work generally. Note that it is not the real structure of modern computers, but the way that modern computers work is nearly the same as in my posts. I am sure that if you understand about the way that computers work in my posts, you will easy to learn about all fields of computer afterward. Thank you !!!
As I mentioned in previous posts, the only thing that is needed to create a computer are gates. Gates must be connected together somehow to perform a specific work. Computers can not perform any work if gates are not connected together.
The first gate that I want to introduce to you is NOT gate. Maybe you remember NAND gate in a previous post. Now we connect two input signals together. When we do, we will have a new gate that is often used in computers. Let’s look at the symbol and truth table below to understand more about it:
You can see that input signals (a and b) will be the same because they are connected together by one wire. Therefore, we will only really have one signal and it can be represented by a triangle instead of D-shape in the NAND gate. Concurrently, the truth table will be simplified very much. Look at the picture below to see the difference:
The second gate that I want to introduce to you is AND gate. Now, the action that we perform is to connect two gates NAND and NOT together to form a new gate with different results. Like this:
This gate is used regularly and regarded as a single gate in computers (although it is a combination of two gates). So, we can modify symbol and truth table of the AND gate like this:
You can see the little circle after the D-shape of the NAND gate is deleted. Concurrently, “x” wire and NOT gate disappeared from the symbol and so the truth table will be simpler than before (“x” column is deleted from the truth table).
Look at the truth table of AND gate. You can see the results are opposite to the NAND gate. You can easily think that NAND = NOT + AND. From there, you can see the result of NAND gate is negative of AND gate.
In conclusion, we only have one thing in computers, that are bits. Bits are controlled by gates and all gates will be formed from NAND gates (as demonstrated above). So, all things that you need to know for understanding how computers work is understanding NAND gates. Thanks for reading and see you again.
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