Understanding Gates – NOT Gate - Know the Code

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The NOT gate in both circuitry and software represent an inverse or opposite state. It’s an inverter, meaning it flips the state and returns the opposite of it.

Your key takeaways for this episode are:

NOT works the same in circuitry as it does in code
The NOT gate (or the ! in your code) gives you the opposite-or inverse-state

Study Notes

NOT = Inverse (Opposite state)

What is the opposite state of the following?:

On (off)
Ok (not ok)
True (false)
1 (0)
Go (stop)

Inverse Relay Logic

In inverse relay logic, when the relay is off, the natural state is connected. It is connected because it has a full circuit from the source to the ground.

NOT Gate Relay

Truth Tables

Switch (input)	Light bulb (output)
Off	On
On	Off

NOT Gate

Let’s check out this piece of code for example:

	<?php
	if (! is_page() ) {
	showTopbar();
	}

view raw not-gate.php hosted with ❤ by GitHub

So, if the state is true, that is, if it’s NOT a page, then the showTopbar() function will run.

`is_page()`	`showTopbar()`
False (off)	Fires (on)
True (on)	Does not fire (off)

NOT Gate circuit

External Reference Articles

Electrical contacts – normally open vs normally closed

Break. Go rest your noodle for a couple of minutes.

Episodes

Total Lab Runtime: 01:53:22

1 Lab Introductionfree 02:20
2 Understanding Switch Logicfree 13:36
3 Introduction to Pseudocode and Truth Tablesfree 16:28
4 Understanding Gates – NOT Gatefree 10:10
5 Understanding Gates – AND Gatefree 15:07
6 Understanding Gates - OR Gatefree 10:33
7 Understanding Gates – XOR Gatefree 10:42
8 Understanding Gates – NAND Gatefree 07:10
9 Understanding Gates – NOR Gatefree 06:34
10 Basics of Memory Circuit – S-R Latchfree 04:41
11 Basics of the Adder Circuitfree 16:01

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