Thursday, June 2, 2011

How a computer boots

I believe I also mentioned I am a computer nerd. Yesterday a friend got back her laptop after having it repaired due to a bad monitor or something. They actually replaced the monitor, the monitor cable, and her motherboard, which I don't understand why the motherboard, based on her symptoms it sounded more like monitor itself. She asked what a motherboard is and my response was:

Usually in a laptop thats one of the first to die since it gets bent around so much. As for your motherboard, based on your symptoms I highly doubt they needed to replace it. Based on the symptoms you listed a while back…the issue should have been fixed with just one thing being replaced. Please tell me it was covered under warranty.

The motherboard connects the CD drive, monitor, keyboard, touchpad, CPU (brain of computer), GPU (makes stuff pretty), wireless card, USB ports, and EVERYTHING else to EVERYTHING. Oh, and it has the BIOS/CMOS chips…the chips needed to even start the computer. The fact that you could at least see the manufacturer logo means the motherboard was ok (or was it you could see the windows logo?)

Ok, thats not too bad, just simple explanation of what the mother board does. Problem is I don't stop and this happens:

****Start of technical stuff which can be skipped if desired****

1. When you press the power button a chip in the computer senses the current travel from the power source (PSU) of either wall or battery, and the chip locks open, sending power to

2. BIOS, which when first given power check every major component of the system, the motherboard itself, the CPU, the memory (RAM), GPU, and on some computer the keyboard. This tends to be in roughly that order. Depending on the system and settings the system will also check the WIFI, CD-Rom, Harddrive, and Floppy drive

a. When the motherboard fails, you might not hear anything start up.

b. The CPU is then checked. From this point on, if there is a problem, either the onboard speaker will beep a pattern or flash lights in a certain pattern. This pattern can be used to identify what component has failed.

c. The RAM is checked to make sure it can be read/written. BIOS also checks to see if you have added or removed any.

d. If there is one, the GPU is checked. If there is a separate GPU, this is when the manufacturer logo appears. Otherwise the graphic is handled by the CPU at this time

0. When given power the monitor backlights, either florescent tubes or LED lights are lit.

1. The BIOS sends the image of the logo and some text to the GPU, which then sends it via cable to the monitor

2. The monitor screen is then updated extremely quickly (usually 5-8 milliseconds) one pixel at a time.

a. Each pixel contains 3 sub pixels, one red, one green, and one blue. sometimes a sub pixel will break and the shutter of the sub pixel is either open or closed, leaving a small color dot at that spot. Most manufacturers allow unto 8 stuck pixels, after which they replace the screen during or even after production. In the case of your old computer there are 1024*768*3=2,359,296 sub pixels, each of which could go dead when the screen is made or after being used

e. Other systems are checked

3. When this check is complete, the computer is said to have passed POST, the Pre-Operating System Test.

4. During the last three steps, the hard drive is spun up from a dead stop to 45,000 RPM-100,000 RPM depending on the type of drive.

5. Once the hard drive is spinning at full speed, BIOS looks for the Master Boot Record (MBR) which says which partition(s) to boot from

6. As per the MBR, the BIOS looks for a certain file on the drive, normally hidden to you, which tell the BIOS to then load more files.

7. These file are loaded into RAM and ran. At this point these boot files take over and the BIOS is no longer in charge.

8. One of these files that are loaded makes the windows logo onscreen which is displayed while drivers and other system files are loaded into RAM and activated. This is when a Blue Screen of Death can start occurring.

9. Once all drivers kick in and everything needed is loaded, you can finally start using the computer.


10. When you tell Windows to shutdown or restart, the quit command is sent to everything currently running.

11. After waiting, if stuff is still running the kill command will be sent…this will force the program to shut

12. Once all of the top stuff is done, the very basics of the operating system clean up caches and write anything that needs to be written

13. When Windows is done, it sends the halt (shutdown) or reboot (restart) command to the BIOS.

14. if reboot is sent, then we go back to step 2

15. if halt is sent, then the power system is disconnected to almost all components. The power button chip is then set to off

a. there is always some power going to the BIOS so BIOS can remember your last settings (there is also a watch battery to give it power if the normal PSUs are disconnected

b. there is also a little power that goes to the wired internet connection for something called Wake on Lan, which when a special signal is received by your network card, the computer will boot

****End of technical stuff****

It is quite informative but long really, did anyone read all of it? Its ok if you didn't, I understand. What is worse is sometimes I talk like this too. But hey, some day you will be trying to start your computer and something is going wrong and you see the Windows Startup Screen before it crashes to the blue screen, and you take it into get it repaired and they will tell you its 500$ to fix since they need to replace some parts. But you know better, you know your computer made it to step 8, and if they need to replace the motherboard, it wouldn't have made it to step 3. (IF its getting that far its a problem with the OS and depending on the issue it is EASY to fix.

Oh, and after that, I did the same thing to her twice more in the same message!

From the guy with his eye on the sky, Travis...the Camping Lifeguard

And just incase anyone wants to read the other to make a periscope, and how to get enough of a voltage for electrofishing when the water is not conductive enough, that is below

****Technical stuff to follow*****

all you would need is a PVC tube including a 90° bend with a mirror at the corner/corners. it would be ok if there was water in it even if I remember correct. Hardest part would be the mirror, but as I think about it, you cut one tube at a 45° joint, then turn one section 180 and reconnect it to get the bend. Then you just need a correctly sized piece of cardboard with smooth tinfoil glued into the corner at a 45° angle from both tubes, where the bottom of the mirror is lined up with the inner side of the vertical piece. I can draw you a picture if you want. if the inner diameter of the tube is x, the shape of the mirror would be oval shaped and size of the mirror would be for width would be x, the length of it would be 2√(2) (because the mirror would form a triangle where the base and height are x since you want no overlap of the mirror to the pipe, else you will lose some of what you could see)

I am not as knowledgeable on the fly in optics but with the right pieces you can make it like binoculars where they magnify
****End Technical stuff****

Oh…now I want to build one of these for the beach
As for zapping them, would either of these ideas work:
1. To increase the ions of the water, have someone upstream add salt? Salt increases the conductivity of the water and is temporary.
2. I just wikipeidad the electroshocking of fish and see it uses DC current.
a. A tazer can produce as much as 500,000V DC. To use that, two things need to happen, first you need to put rubber between the two contacts to prevent the normal arc. second you would want to run wires from both ends of the tazer into the water.

****Begin yet more crazy technical stuff****

I know this sounds dangers, but here is what you have to remember, and you may already know this, but when trying to generate a spark from a tazer or just current flow, you need a high enough voltage to overcome the resistance of whats in the way, such as air or water. In air, the resistance is about 2x10^16 Ω/m where as the eater you are probably in is closer to like drinking water at 200Ω/m if its really clean and salt water is .2Ω/m. Ohm's law says I=V/R, which I is current in Amps, V is voltage of device, and R is resistance. According to, the voltage you need to zap a fish is about 3 amps. To achieve that, using your fish thing at 990V, I=V/R --> 3A=990/R*3M (about the distance from your rod and line for the fish thing. get R to one size and you get 1/3 = R*3/990 --> 990/(3*3m) = a max water resistance of 100Ω/m, which is the lower end of really good drinking water ( A tazor with the contacts 3 meters apart would be 3A=500000V/R*3M -->500000/3A*3M = R = 55555Ω/M or 5.6x10^4Ω/M, which is about ⅓ that of deionized water. so if its really bad you can do 1 meter separation you can catch anything in any kind of water!!

****End of the technical stuff…still not sure where crazy ends****

b. Ok, with that insane idea out of the way, what if you took like sticks or holes in PVC and ran 2 or more wires across the stream bed. lets say the stream is 1 meter deep. if a positive wire was running at the surface and negative along the bottom of the river bed, you would get (from above) 3A=990V/R = 330Ω/m water resistance limit, 3 times as much! But electricity is cool. add in a third wire, so positive at the top, negative in the middle, and positive on the bottom of the edge. now you get 3A=990V/R*.5m -->990/3A/.5m = R is 600Ω/m. you can see where I am going, and a 4th wire (from top to bottom is PNPN) and you get 1000Ω/m limit! That should look like

≃≃≃≃≃≃≃≃≃≃≃≃≃ -water level, top power line: P
\____________/ - N
\__________/ - P
\________/ - N

Just by moving the parts of the zapper closer together we have increased shock level by 10! What happens is the amps are spread out but the voltage between two wires is still the same. When the fish gets passes thru, it will get zapped no matter which level, and the flow that would go to other wires go to the two zapping the fish, which does make the others temporally weaker. Got it? its ok if you don't. Oh, and when you connect the P wires together, do it out of the water where they touch the positive end of your zapper, and same with the negative. at least in the water you don't want them too close together. out of the water as long as you don't see sparks its fine. To test stick your hand thru it…i don't know if you have done it with the fish zapper just sticking your hand into the water…3 volts itsnt bad at all…our electric sheep fence is measuring a possible 1KV and it just tingles a little (though I do have shoes on)(we need about 6KV to actually prevent the sheep from getting out *roll eyes*

Why are there fruit flies in my room? All I have is some peanuts and catnip.

No comments:

Post a Comment