Logic gates are like tiny little switches that can turn electricity on or off in a computer. They are used to make decisions, like whether to let electricity flow through or to stop it. Computers use logic gates to store and process information, like numbers and words.
For example, if you wanted to make a simple computer that can add two numbers together, you would need to use some logic gates. You would start by using a logic gate called an “AND” gate to check if the two numbers are both bigger than zero. If they are, then the AND gate would let electricity flow through.
There are 3 basic types of logic gates which you should know about and which we will cover below.
Basic Logic Gates
An AND gate is a type of logic gate that only lets electricity flow through if both of the inputs are “on” or “true”. Imagine it like a door that only opens if you have the right key AND the right password.
An OR gate is a type of logic gate that lets electricity flow through if either of the inputs is “on” or “true”. Imagine it like a door that opens if you have the right key OR the right password.
A NOT gate is a type of logic gate that inverts the input. If the input is “on” or “true”, the output will be “off” or “false”. If the input is “off” or “false”, the output will be “on” or “true”. Imagine it like a light switch – if the light is on, flipping the switch will turn it off, and if the light is off, flipping the switch will turn it on.
These logic gates are all very simple, but they are the building blocks that computers use to store and process information. They are like the letters of the alphabet – by themselves, they are simple, but when you put them together in the right way, you can create all sorts of complex and interesting things.
Logic Circuits
A logic circuit is a way of using logic gates to process information. Imagine it like a bunch of tiny little switches that are all connected together in a specific way. Each switch can turn electricity on or off, and the way they are connected determines what the logic circuit does.
Imagine you want to build a logic circuit that can turn a light on or off based on the time of day. You could use a NOT gate followed by an OR gate. The NOT gate would invert the input from the light sensor, and the OR gate would have two inputs, A and B. Input A would represent the inverted output from the light sensor, and input B would represent whether it is nighttime. If either A or B is “true”, then the OR gate will allow electricity to flow through and turn the light on. If both A and B are “false”, then the OR gate will not allow electricity to flow, and the light will stay off.
To make this logic circuit work, you would need to use some sensors to detect the time of day and send a “true” or “false” signal to the OR gate. For example, you could use a light sensor to detect if it is daytime and a temperature sensor to detect if it is night time. If it is daytime, the light sensor would send a “true” signal to the NOT gate, which would invert the signal and send a “false” signal to input A of the OR gate. The temperature sensor would send a “false” signal to input B of the OR gate. This would cause the OR gate to not allow electricity to flow, and the light would stay off.
If it is night time, the light sensor would send a “false” signal to the NOT gate, which would invert the signal and send a “true” signal to input A of the OR gate. The temperature sensor would send a “true” signal to input B of the OR gate, which would cause the OR gate to allow electricity to flow and turn the light on.
This is just one example of a simple logic circuit. There are all sorts of different logic circuits that can do all sorts of different things, and they are all very important for making computers work.
