View full lesson: http://ed.ted.com/lessons/inside-your-computer-bettina-bair
How does a computer work? The critical components of a computer are the peripherals (including the mouse), the input/output subsystem (which controls what and how much information comes in and out), and the central processing unit (the brains), as well as human-written programs and memory. Bettina Bair walks us through the steps your computer takes with every click of the mouse.
Lesson by Bettina Bair, animation by Flaming Medusa Studios.
Do you remember when you first realizethat your computer was morthan just a monitor and keyboardThat between the mouse clicand the video playingthere was somethinthat captured your intentionunderstood itand made it realWhat is that somethingIs it gremlinsLet's imagine that we can shrink dowto the size of an electroand inject ourselveinto a click of a mouse.
If you took your mouse apartyou'd see that it's realla very simple machine.
It has a couple buttonand a system for detectinmotion and distance.
You might have an optical mousthat makes these measurementwith lights and sensorsbut older ones did thiwith a hard rubber baland some plastic wheels.
Same concept.
When you click the button on your mouseit sends a message to the computewith information about its position.
When your mouse click is receivedit's handled by the basiinput/output subsystem.
This subsystem acts like the eyes and earand mouth and hands of the computer.
Basically, it providea way for the computeto interact with its environment.
But it also acts like a buffeto keep the CPU from beinoverwhelmed by distractions.
In this case, the I/O subsystem decidethat your mouse click is pretty importanso it generates an interrupt to the CPU.
"Hey, CPU! Got a click here.The CPU, or central processing unitis the brains of the whole computer.
Just like your brain doesn'take up your whole bodythe CPU doesn't takup the whole computerbut it runs the show all the same.
And the CPU's job, its whole jobis fetching instructions from memorand executing them.
So, while you're typing, typing, typingmaybe really fastlike 60 words a minutethe CPU is fetching and executinbillions of instructions a second.
Yes, billions every secondinstructions to move your mousaround on the screento run that clock widget on your desktopplay your internet radiomanage the files you'rediting on the hard driveand much, much more.
Your computer's CPis one heck of a multitasker"But oh my gosthere's a very important mouse cliccoming through nowLet's drop everything noand deal with that!There are programs for everythinthat the CPU does.
A special program for the mousefor the clock widgetfor the internet radioand for dealing with lettersent by the keyboard.
Each program was initiallwritten by a humain a human-readable programming languagelike JavaC++or Python.
But human programs take up a lot of spacand contain a lot of unnecessarinformation to a computerso they are compiled and made smalleand stored in bits of oneand zeros in memory.
The CPU realizes that ineeds instructionfor how to deal with this mouse clickso it looks up the addresfor the mouse prograand sends a requesto the memory subsystefor instructions stored there.
Each instructioin the mouse device driveis duly fetched and executed.
And that's not nearlthe end of the storyBecause the CPU learnthat the mouse was clickewhen the cursor was over a picturof a button on the monitor screenand so, the CPU asks memorfor the monitor prograto find out what that button is.
And then the CPU has to ask memorfor the program for the buttonwhich means that the CPU needthe monitor program agaito show the videassociated with the buttonand so it goes.
And let's just say therare a lot of programs involvebefore you even sethe button on the screelight up when you clicked it.
So, just the simple tasof clicking your mousmeans visitinall of the critical componentof your computer's architectureperipheralsthe basic input-output systemthe CPUprogramsand memoryand not one gremlin.