What is an operating system?
Listening to music while searching, and getting messages too. How does one computer do all of this at once? Behind the screen is an invisible keeper.
All we see are the apps
When you turn on a computer,
what we see
are the apps.
Messages, music, the browser.
But underneath them,
someone we can't see
is always working.
Shall we lift the lid?
Lift up what's under the screen.
This thing holding up the apps.
This is the operating system.
We shorten it to OS.
Windows, Android, iOS.
You've heard the names.
These are all operating systems.
It sits between apps and hardware
The OS's place
is right in the middle.
Above are the apps we use,
below is the hardware we saw earlier,
parts like the CPU and memory.
The OS
sits between them
and connects the two.
Where the OS sits.
Apps don't touch
the parts directly.
Instead they ask the OS.
"Give me some memory,
open this file for me."
The OS
takes those requests and handles them.
It looks after countless apps at once
On a computer,
many apps always run at once.
Music has to make sound,
the browser has to draw the screen,
messages have to pop up alerts.
The OS takes all these requests
at once
and handles them in order.
The OS handles the apps' requests.
To our eyes
it all seems to happen at once,
but really the OS
is switching back and forth very fast,
looking after them.
We'll see how it does that
in detail next time.
It mediates so things get shared
There's only one of a part,
but many apps want to use it.
The speaker, for example, is one.
If music and an alert
both try to make sound at once?
The OS mediates.
It's the referee
deciding who uses it and when.
Sharing a part there's only one of.
What if there were no referee?
Two apps at once
would fight over the same part,
crash, and freeze.
Because the OS keeps order,
we use many apps with peace of mind.
What if there were no OS
The best way to feel
what an OS does
is to imagine there isn't one.
Switch the toggle below.
How different it is
with and without
will be clear at a glance.
Switch the toggle.
With an OS
the apps run together nicely,
without it they collide into a mess.
Thanks to this invisible keeper,
we use a computer with ease,
without knowing the complicated parts.