How does a computer actually work?

That requires a pretty complicated answer if you want to get down to the microscopic level.

Processors have millions of transistors
Video cards often have their own processors with transistors.

Basically
The keyboard sends a signal to the computer to designate which key was pressed.
The processor constantly cycles through running processes.
When the processor gets to the specific program that is active and waiting for keyboard input it reads the signal from the keyboard.
The keyboard input is processed based on the program to figure out what it is supposed to do with it.
If it is to be outputted to the screen then it figures out where it should go and creates the proper screen output.
The screen output is kept in a certain part of memory on the computer board or now often on the video card.
When the output is changed in that memory then the screen changes and you see the character on your screen.



Unless you are an engineer designing the system from ground up what is happening at the microscopic level isn't that important. You only want certain input to give the required output.

Think of the transistors as a million switches. Most of the switches are controlled by which other switches are turned on or off. You only need to turn on and off 16 of the switches to control what your final output is. You don't really care what the other million switches are doing as long as you turn the 16 on correctly to give you the result you want out the other end.

I would like to know if threre is time to explain,

where I lose the understanding is in the electrical signal and binary levels.

Many pages of detail and images on the subject can be found here:

http://computer.howstuffworks.com/computer-hardware-channel.htm

http://computer.howstuffworks.com/pc.htm

Thanks i have read quite abit about how computers work from various sites but cant find anything really in depth like the question im asking.

what i'd like to see is the electrical signal going on its journey in text or animation.

like para said if i was an engineer i would need to know how to build from nothing.

The question you ask isn't that simple and I don't have the time to do a lot of the leg work for you. I will point you in a few directions that you can explore on your own.

This is a comprehensive topic index. You basically need to understand how all these components work to also understand how the power flows to and through them.

http://www.pcguide.com/topic.html

I would start with this section on the basic electrical components then use the index to navigate to the sections on Power and then move through the section on Mother Boards.

The first thing you need to learn is how a transistor works.


Then you can start to learn how an electrical circuit works.

http://www.kpsec.freeuk.com/trancirc.htm

Then you can start to see what counters and gates do.
http://www.kpsec.freeuk.com/components/74series.htm#74163
and flip flops and all other manner of binary circuitry

All binary means is that there are 2 levels of electrical signal on/off. In order to find what electrical level is considered on and what level is off you need to look at the specifications of the device.

Considering the fact that a processor can do millions of instructions per second and each of those instructions requires the use of thousands if not millions of transistors you will never find an "in depth" explanation of the electrical signals journey. It would be impossible to do so. Usually you will see block diagrams designating the device types that interact in the chip.


Technical sheet for a simple microprocessor, the atmel 89C2051. Check out the block diagram on page 2.
http://www.atmel.com/dyn/resources/prod_documents/doc0368.pdf

I will read all of it, but quickly.......

this really clicked in my brain, when you say levels of signal, how would this equate?

like morse dot and dash is sound and length of signal

what would be a 0 signal and a 1 signal in common use?

0 is 0 volts. 1 is 5 volts in most ICs. I think the newer processor chips use lower voltage such as 3.4 or 2.7 volts.

Basically what happens is there is a clock chip which varies from 0 to 1.
The atmel specs I posted earlier shows timing wave forms at section 21. When the clock moves from 0-1 then the other pins are read.

If the chip is 8 bit then it may have 8 pins to read an 8 bit number, for instance 1111101
So it would read the pins on one clock cycle. When the clock changes it would read the pins again for a new number.

Of course that ignores the fact that keyboards and modems actually send it as a series of on/off pulses on one cable. In that case you would need a counter to count which single number of the 8 is being read and then translate that into the 8 bits needed for the processor.

thats spot on, Thanks i will contiune to read.