eli5: At the most basic level, how is a computer programmed to know how long a unit of time is?
In: 2404
There are certain crystals that vibrate when we apply electricity to them. We can exploit that vibration to make a device that opens and closes an electrical switch as it vibrates. That sends a “pulse” of electricity and we call this a “clock”.
The neat thing about these crystals is they vibrate at pretty much exactly the same frequency no matter what. So if we build a circuit that counts how many “pulses” have been sent, we know when it reaches a certain number 1 second has passed. We can use math to figure out smaller units of time.
The CPU in a computer already has to have a “clock” line. That periodic on and off pulsing is what tells it to perform its next instruction, it’s kind of like turning the crank on a jack in the box. So it can count these “cycles” to have an idea of the passage of time.
There are certain crystals that vibrate when we apply electricity to them. We can exploit that vibration to make a device that opens and closes an electrical switch as it vibrates. That sends a “pulse” of electricity and we call this a “clock”.
The neat thing about these crystals is they vibrate at pretty much exactly the same frequency no matter what. So if we build a circuit that counts how many “pulses” have been sent, we know when it reaches a certain number 1 second has passed. We can use math to figure out smaller units of time.
The CPU in a computer already has to have a “clock” line. That periodic on and off pulsing is what tells it to perform its next instruction, it’s kind of like turning the crank on a jack in the box. So it can count these “cycles” to have an idea of the passage of time.
Imagine you are listening to the sound of a continuously bouncing football kept inside a small transparent box. Every time it bounces, you hear the sound non-stop.
Inside a computer, there is a tiny chip or material called a quartz crystal, which is made of silicon dioxide (SiO2), the same material that makes up sand and most rocks. Quartz crystals are piezoelectric, meaning that they generate an electric charge at precise and consistent intervals when subjected to an electric voltage.
Just like listening to the continuous bouncing of a football, in computers, there is a chip that senses the generated electric charge by this crystal. It sends this electric charge (signal) to all other chips that require this continuous signal to alter their own chip structure, which at a higher level is what we perceive as computation, processing, and programming.
There is a chip in the pc that contains a quartz crystal that vibrates at a known speed when a small amount of electricity is run through it. That chip is connected to a watch battery – and contains a counter that counts how many times it has vibrated – which is essentially a count of fractions of a second since the battery was connected. You set the time to tell it a point to start counting from, and then from there, it counts.
Open your PC, you will see a battery the size of a quarter. If your PC stops keeping time correctly when you turn it off, replace that battery.
Imagine you are listening to the sound of a continuously bouncing football kept inside a small transparent box. Every time it bounces, you hear the sound non-stop.
Inside a computer, there is a tiny chip or material called a quartz crystal, which is made of silicon dioxide (SiO2), the same material that makes up sand and most rocks. Quartz crystals are piezoelectric, meaning that they generate an electric charge at precise and consistent intervals when subjected to an electric voltage.
Just like listening to the continuous bouncing of a football, in computers, there is a chip that senses the generated electric charge by this crystal. It sends this electric charge (signal) to all other chips that require this continuous signal to alter their own chip structure, which at a higher level is what we perceive as computation, processing, and programming.
We build every computer with a tiny electronic watch inside of them that can keep time. It works the same way as electronic watches do. It’s not perfectly accurate, but it works very, very well on its own, and then if you really need to you can also use the internet to synch it up with external references.
The tech used for electronic timekeeping is called the [quartz crystal oscillator](https://en.wikipedia.org/wiki/Crystal_oscillator). Basically, it works because quartz crystals change their shape when electric currents are applied to them. If you make the amount of electric current applied to the quartz crystal dependent on the crystal’s shape, then you can make a circuit that oscillates back and forth in a really-regular way, and then count those oscillations to do timekeeping.
There is a chip in the pc that contains a quartz crystal that vibrates at a known speed when a small amount of electricity is run through it. That chip is connected to a watch battery – and contains a counter that counts how many times it has vibrated – which is essentially a count of fractions of a second since the battery was connected. You set the time to tell it a point to start counting from, and then from there, it counts.
Open your PC, you will see a battery the size of a quarter. If your PC stops keeping time correctly when you turn it off, replace that battery.
Imagine you are listening to the sound of a continuously bouncing football kept inside a small transparent box. Every time it bounces, you hear the sound non-stop.
Inside a computer, there is a tiny chip or material called a quartz crystal, which is made of silicon dioxide (SiO2), the same material that makes up sand and most rocks. Quartz crystals are piezoelectric, meaning that they generate an electric charge at precise and consistent intervals when subjected to an electric voltage.
Just like listening to the continuous bouncing of a football, in computers, there is a chip that senses the generated electric charge by this crystal. It sends this electric charge (signal) to all other chips that require this continuous signal to alter their own chip structure, which at a higher level is what we perceive as computation, processing, and programming.
There is a chip in the pc that contains a quartz crystal that vibrates at a known speed when a small amount of electricity is run through it. That chip is connected to a watch battery – and contains a counter that counts how many times it has vibrated – which is essentially a count of fractions of a second since the battery was connected. You set the time to tell it a point to start counting from, and then from there, it counts.
Open your PC, you will see a battery the size of a quarter. If your PC stops keeping time correctly when you turn it off, replace that battery.
We build every computer with a tiny electronic watch inside of them that can keep time. It works the same way as electronic watches do. It’s not perfectly accurate, but it works very, very well on its own, and then if you really need to you can also use the internet to synch it up with external references.
The tech used for electronic timekeeping is called the [quartz crystal oscillator](https://en.wikipedia.org/wiki/Crystal_oscillator). Basically, it works because quartz crystals change their shape when electric currents are applied to them. If you make the amount of electric current applied to the quartz crystal dependent on the crystal’s shape, then you can make a circuit that oscillates back and forth in a really-regular way, and then count those oscillations to do timekeeping.
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