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hi, recently, i had the wonderful opportunity to have watched a video on how bacteria communicate with each other. Bonnie Bassler and her fellow colleagues have carried out a research on how bacteria 'talk' to each other and the possible ways of curing infectious diseases caused by pathogenic bacteria. She reckons that using a reverse way of how bacteria communicate with each other, the possibility of hindering the collective attack of these pathogenic bacteria may one day be a realized dream. 

 this is the talk which she has given to the audience during one of the programmes organised by a famous ideas sharing website, TED


Bacteria are the oldest living organisms on the earth. They've been here for billions of years, and what they are are single-celled microscopic organisms. So they are one cell and they have this special property that they only have one piece of DNA. They have very few genes, and genetic information to encode all of the traits that they carry out. And the way bacteria make a living is that they consume nutrients from the environment, they grow to twice their size, they cut themselves down in the middle, and one cell becomes two, and so on and so on. They just grow and divide, and grow and divide -- so a kind of boring life, except that what I would argue is that you have an amazing interaction with these critters.

I know you guys think of yourself as humans, and this is sort of how I think of you. This man is supposed to represent a generic human being,and all of the circles in that man are all of the cells that make up your body. There is about a trillion human cells that make each one of us who we are and able to do all the things that we do, but you have 10 trillion bacterial cells in you or on you at any moment in your life. So, 10 times more bacterial cells than human cells on a human being. And of course it's the DNA that counts, so here's all the A, T, Gs and Cs that make up your genetic code, and give you all your charming characteristics. You have about 30,000 genes.Well it turns out you have 100 times more bacterial genes playing a role in you or on you all of your life.At the best, you're 10 percent human, but more likely about one percent human, depending on which of these metrics you like. I know you think of yourself as human beings, but I think of you as 90 or 99 percent bacterial.

(Laughter)

These bacteria are not passive riders, these are incredibly important, they keep us alive. They cover us in an invisible body armor that keeps environmental insults out so that we stay healthy.They digest our food, they make our vitamins, they actually educate your immune system to keep bad microbes out. So they do all these amazing thingsthat help us and are vital for keeping us alive, and they never get any press for that. But they get a lot of press because they do a lot of terrible things as well. So, there's all kinds of bacteria on the Earththat have no business being in you or on you at any time, and if they are, they make you incredibly sick.

And so, the question for my lab is whether you want to think about all the good things that bacteria do, or all the bad things that bacteria do. The question we had is how could they do anything at all? I mean they're incredibly small, you have to have a microscope to see one. They live this sort of boring life where they grow and divide, and they've always been considered to be these asocial reclusive organisms. And so it seemed to us that they are just too small to have an impact on the environment if they simply act as individuals.And so we wanted to think if there couldn't be a different way that bacteria live.

The clue to this came from another marine bacterium, and it's a bacterium called Vibrio fischeri. What you're looking at on this slide is just a person from my lab holding a flask of a liquid culture of a bacterium, a harmless beautiful bacterium that comes from the ocean, named Vibrio fischeri. This bacterium has the special property that it makes light, so it makes bioluminescence, like fireflies make light. We're not doing anything to the cells here. We just took the picture by turning the lights off in the room, and this is what we see.

What was actually interesting to us was not that the bacteria made light, but when the bacteria made light. What we noticed is when the bacteria were alone, so when they were in dilute suspension, they made no light. But when they grew to a certain cell number all the bacteria turned on light simultaneously. The question that we had is how can bacteria, these primitive organisms, tell the difference from times when they're alone, and times when they're in a community, and then all do something together.What we've figured out is that the way that they do that is that they talk to each other, and they talk with a chemical language.

This is now supposed to be my bacterial cell.When it's alone it doesn't make any light. But, what it does do is to make and secrete small moleculesthat you can think of like hormones, and these are the red triangles, and when the bacteria is alonethe molecules just float away and so no light. But when the bacteria grow and double and they're all participating in making these molecules, the molecule -- the extracellular amount of that molecule increases in proportion to cell number.And when the molecule hits a certain amount that tells the bacteria how many neighbors there are,they recognize that molecule and all of the bacteria turn on light in synchrony. That's how bioluminescence works -- they're talking with these chemical words.

The reason that Vibrio fischeri is doing that comes from the biology. Again, another plug for the animals in the ocean, Vibrio fischeri lives in this squid. What you are looking at is the Hawaiian Bobtail Squid, and it's been turned on its back, and what I hope you can see are these two glowing lobes and these house the Vibrio fischeri cells,they live in there, at high cell number that molecule is there, and they're making light. The reason the squid is willing to put up with these shenanigansis because it wants that light. The way that this symbiosis works is that this little squid lives just off the coast of Hawaii, just in sort of shallow knee deep water. The squid is nocturnal, so during the day it buries itself in the sand and sleeps, but then at night it has to come out to hunt. On bright nights when there is lots of starlight or moonlight that light can penetrate the depth of the water the squid lives in, since it's just in those couple feet of water.What the squid has developed is a shutter that can open and close over this specialized light organ housing the bacteria. Then it has detectors on its back so it can sense how much starlight or moonlight is hitting its back. And it opens and closes the shutter so the amount of light coming out of the bottom -- which is made by the bacterium -- exactly matches how much light hits the squid's back, so the squid doesn't make a shadow. It actually uses the light from the bacteriato counter-illuminate itself in an anti-predation device so predators can't see its shadow,calculate its trajectory, and eat it. This is like the stealth bomber of the ocean.

(Laughter)

But then if you think about it, the squid has this terrible problem because it's got this dying, thick culture of bacteria and it can't sustain that. And so what happens is every morning when the sun comes up the squid goes back to sleep, it buries itself in the sand, and it's got a pump that's attached to its circadian rhythm, and when the sun comes up it pumps out like 95 percent of the bacteria. Now the bacteria are dilute, that little hormone molecule is gone, so they're not making light -- but of course the squid doesn't care. It's asleep in the sand. And as the day goes by the bacteria double, they release the molecule, and then light comes on at night, exactly when the squid wants it.

First we figured out how this bacterium does this,but then we brought the tools of molecular biology to this to figure out really what's the mechanism.And what we found -- so this is supposed to be, again, my bacterial cell -- is that Vibrio fischeri has a protein -- that's the red box -- it's an enzyme that makes that little hormone molecule -- the red triangle. And then as the cells grow, they're all releasing that molecule into the environment, so there's lots of molecule there. And the bacteria also have a receptor on their cell surface that fits like a lock and key with that molecule. These are just like the receptors on the surfaces of your cells.When the molecule increases to a certain amount -- which says something about the number of cells -- it locks down into that receptor and information comes into the cells that tells the cells to turn onthis collective behavior of making light.

Why this is interesting is because in the past decade we have found that this is not just some anomaly of this ridiculous, glow-in-the-dark bacterium that lives in the ocean -- all bacteria have systems like this. So now what we understand is that all bacteria can talk to each other. They make chemical words, they recognize those words, and they turn on group behaviors that are only successful when all of the cells participate in unison. We have a fancy name for this, we call it quorum sensing. They vote with these chemical votes, the vote gets counted, and then everybody responds to the vote.

What's important for today's talk is that we know that there are hundreds of behaviors that bacteria carry out in these collective fashions. But the one that's probably the most important to you is virulence. It's not like a couple bacteria get in youand they start secreting some toxins -- you're enormous, that would have no effect on you. You're huge. What they do, we now understand, is they get in you, they wait, they start growing, they count themselves with these little molecules, and they recognize when they have the right cell numberthat if all of the bacteria launch their virulence attack together, they are going to be successful at overcoming an enormous host. Bacteria always control pathogenicity with quorum sensing. That's how it works.

We also then went to look at what are these molecules -- these were the red triangles on my slides before. This is the Vibrio fischeri molecule.This is the word that it talks with. So,then we started to look at other bacteria, and these are just a smattering of the molecules that we've discovered. What I hope you can see is that the molecules are related. The left-hand part of the molecule is identical in every single species of bacteria. But the right-hand part of the molecule is a little bit different in every single species. What that does is to confer exquisite species specificities to these languages. Each molecule fits into its partner receptor and no other. So these are private, secret conversations. These conversations are for intraspecies communication.Each bacteria uses a particular molecule that's its language, that allows it to count its own siblings.

Once we got that far we thought we were starting to understand that bacteria have these social behaviors. But what we were really thinking about is that most of the time bacteria don't live by themselves, they live in incredible mixtures, with hundreds or thousands of other species of bacteria. And that's depicted on this slide. This is your skin. So this is just a picture -- a micrograph of your skin. Anywhere on your body, it looks pretty much like this, and what I hope you can see is that there's all kinds of bacteria there. And so we started to think if this really is about communication in bacteria, and it's about counting your neighbors, it's not enough to be able to only talk within your species. There has to be a way to take a census of the rest of the bacteria in the population.

So we went back to molecular biology and started studying different bacteria, and what we've found now is that in fact, bacteria are multilingual. They all have a species-specific system -- they have a molecule that says "me." But then, running in parallel to that is a second system that we've discovered, that's generic. So, they have a second enzyme that makes a second signal and it has its own receptor, and this molecule is the trade language of bacteria. It's used by all different bacteria and it's the language of interspecies communication. What happens is that bacteria are able to count how many of me and how many of you. They take that information inside, and they decide what tasks to carry out depending on who's in the minority and who's in the majority of any given population.

Then, again we turn to chemistry, and we figured out what this generic molecule is -- that was the pink ovals on my last slide, this is it. It's a very small five carbon molecule. What the important thing is that we learned is that every bacterium has exactly the same enzyme and makes exactly the same molecule. So they're all using this moleculefor interspecies communication. This is the bacterial Esperanto.

(Laughter)

Once we got that far, we started to learn that bacteria can talk to each other with this chemical language. But what we started to think is that maybe there is something practical that we can do here as well. I've told you that bacteria do have all these social behaviors, they communicate with these molecules. Of course, I've also told you that one of the important things they do is to initiate pathogenicity using quorum sensing. We thought, what if we made these bacteria so they can't talk or they can't hear? Couldn't these be new kinds of antibiotics?

Of course, you've just heard and you already knowthat we're running out of antibiotics. Bacteria are incredibly multi-drug resistant right now, and that's because all of the antibiotics that we use kill bacteria. They either pop the bacterial membrane,they make the bacterium so it can't replicate its DNA. We kill bacteria with traditional antibioticsand that selects for resistant mutants. And so now of course we have this global problem in infectious diseases. We thought, well what if we could sort of do behavior modifications, just make these bacteria so they can't talk, they can't count, and they don't know to launch virulence.

And so that's exactly what we've done, and we've sort of taken two strategies. The first one is we've targeted the intraspecies communication system.So we made molecules that look kind of like the real molecules -- which you saw -- but they're a little bit different. And so, they lock into those receptors, and they jam recognition of the real thing. By targeting the red system, what we are able to do is to make species specific, or disease specific anti-quorum sensing molecules. We've also done the same thing with the pink system.We've taken that universal molecule and turned it around a little bit so that we've made antagonistsof the interspecies communication system. The hope is that these will be used at broad spectrum antibiotics that work against all bacteria.

To finish I'll just show you the strategy. In this one I'm just using the interspecies molecule, but the logic is exactly the same. What you know is that when that bacterium gets into the animal, in this case, a mouse, it doesn't initiate virulence right away. It gets in, it starts growing, it starts secretingits quorum sensing molecules. It recognizes when it has enough bacteria that now they're going to launch their attack, and the animal dies. What we've been able to do is to give these virulent infections, but we give them in conjunction with our anti-quorum sensing molecules -- so these are molecules that look kind of like the real thing, but they're a little bit different which I've depicted on this slide. What we now know is that if we treat the animal with a pathogenic bacterium -- a multi-drug resistant pathogenic bacterium -- in the same time we give our anti-quorum sensing molecule, in fact, the animal lives.

We think that this is the next generation of antibiotics and it's going to get us around, at least initially, this big problem of resistance. What I hope you think, is that bacteria can talk to each other,they use chemicals as their words, they have an incredibly complicated chemical lexicon, that we're just now starting to learn about. Of course what that allows bacteria to do is to be multicellular. So in the spirit of TED they're doing things togetherbecause it makes a difference. What happens is that bacteria have these collective behaviors, and they can carry out tasks that they could never accomplish if they simply acted as individuals.

What I would hope that I could further argue to youis that this is the invention of multicellularity.Bacteria have been on the Earth for billions of years. Humans -- couple hundred thousand. We think bacteria made the rules for how multicellular organization works. We think, by studying bacteria,we're going to be able to have insight about multicellularity in the human body. We know that the principles and the rules, if we can figure them out in these sort of primitive organisms, the hope is that they will be applied to other human diseases and human behaviors as well. I hope that what you've learned is that bacteria can distinguish self from other. By using these two molecules they can say "me" and they can say "you." Again of course that's what we do, both in a molecular way, and also in an outward way, but I think about the molecular stuff.

This is exactly what happens in your body. It's not like your heart cells and your kidney cells get all mixed up every day, and that's because there's all this chemistry going on, these molecules that say who each of these groups of cells is, and what their tasks should be. Again, we think that bacteria invented that, and you've just evolved a few more bells and whistles, but all of the ideas are in these simple systems that we can study.

The final thing is, again just to reiterate that there's this practical part, and so we've made these anti-quorum sensing molecules that are being developed as new kinds of therapeutics. But then, to finish with a plug for all the good and miraculous bacteria that live on the Earth, we've also made pro-quorum sensing molecules. So, we've targeted those systems to make the molecules work better. Remember you have these 10 times or more bacterial cells in you or on you, keeping you healthy. What we're also trying to do is to beef up the conversation of the bacteria that live as mutualists with you, in the hopes of making you more healthy, making those conversations better,so bacteria can do things that we want them to dobetter than they would be on their own.

Finally, I wanted to show you this is my gang at Princeton, New Jersey. Everything I told you about was discovered by someone in that picture. I hope when you learn things, like about how the natural world works -- I just want to say that whenever you read something in the newspaper or you get to hear some talk about something ridiculous in the natural world it was done by a child. Science is done by that demographic. All of those people are between 20 and 30 years old, and they are the engine that drives scientific discovery in this country. It's a really lucky demographic to work with. I keep getting older and older and they're always the same age, and it's just a crazy delightful job. I want to thank you for inviting me here. It's a big treat for me to get to come to this conference.

(Applause)

Thanks.

(Applause)

What to watch next

anyway, that was the wonderful speech which she has delivered... hope it had been informative... 

 

 

WHY DOES A CRANE LIFT UP A LEG WHEN IN THE WATER?

WHILE MANY MIGHT PONDER ON THAT QUESTION , IT IS NOT AN ASTROLOGICAL SURPRISE THAT SOME MIGHT EVEN RESORT TO SHRUG OFF THAT QUESTION FROM THE INNARDS OF THEIR MIND. IT IS A DEFINITELY WONDERFUL THING TO EVER IMAGINE WHY A  FLAMINGO OR PERHAPS A CRANE , IN THE DEPTHS OF A POND, WOULD EVER WANT TO LIFT UP A LEG. WELL, LET ME ANSWER YOU

  THE CRANE HAS TO RETAIN AND MAINTAIN ITS BODY TEMPERATURE AT THE OPTIMUM POINT. HOWEVER, IT HAS THE ABILITY TO DO SO ONLY WHEN IT IS COVERED WITH FEATHERS. THAT MEANS FOR THE UPPER PART OF THE BODY, IT DOESNT SEEM TO HAVE ANY PROBLEMS IN KEEPING THE HEAT IN ITS BODY AS WE ALL KNOW THAT IT IS ENTIRELY COVERED WITH FEATHERS..... HOWEVER, WITH GOD'S GRACE, IT DOESNT HAVE FEATHERS ON ITS LEGS AND HENCE LOSES THE HEAT TO THE WATER ( SINCE IT STANDS IN THE WATER ). TO REDUCE THE HEAT LOSS TO THE WATER, IT LIFTS UP A LEG AT LEAST ( OBVIOUSLY NOT BOTH !!) AND TUCKS IT CLOSE TO ITS BODY TO ABSORB THE HEAT BEING LOST.... ANS IT OFF COURSE DOESNT MIND STANDING ON THE ONE LEG FOR A NIGHT LONG....

 HOW CALCULATORS WORK???????


 Most calculators depend on integrated circuits, commonly known as chips. These circuits use transistors to add and subtract, as well as to perform computations on logarithms in order to accomplish multiplication, division and more complicated operations such as using exponents and finding square roots. Basically, the more transistors an integrated circuit has, the more advanced its functions may be. Most standard pocket calculators have identical, or very similar, integrated circuitry.

Like any electronic device, the chips inside a calculator work by reducing any information you give it to its binary equivalent. Binary numbers translate our numbers in a base-two system, in which we represent each digit by a 1 or a 0, doubling each time we move up a digit. By "turning on" each of the positions -- in other words, by putting a 1 in it -- we can say that that digit is included in our overall number.

Microchips use binary logic by turning transistors on and off literally, with electricity. So, for example, if you wanted to add 2 + 2, your calculator would convert each "2" to binary (which looks like this: 10) and then add them together. Adding the "ones" column (the two 0s), gives you 0: The chip can see that there is nothing in the first position. When it adds the digits in the "tens" column, the chip gets 1+1. It sees that both are positive, and -- since there are no 2's in binary notation -- moves the positive reply one digit to the left, getting a sum of 100 -- which, in binary terms, equals 4 [source: Wright].

This sum is routed through the input/output chip in our integrated circuit, which applies the same logic to the display itself. Have you ever noticed the way the numbers on a calculator or alarm clock are made up of segmented lines? Each one of those parts of the numerals can be turned on or off using this same binary logic. So, the processor takes that "100" and translates it by lighting up or turning on certain segments of the lines in the display to create the numeral 4.

The calculator has had a profound impact on the world, making computations quicker and more exact. In the classroom, calculators have given many students the ability to learn about and put complex formulas and concepts into practice more easily. Especially in lower-grade mathematics courses, some instructors still don't allow their use to make sure students truly understand mathematical concepts and learn problem-solving techniques. But for many calculus and trigonometry courses in high school, for example, graphing calculators are a requirement.

However, there has been some controversy regarding the use of powerful calculators in class, because some believe that using the devices to do the work that people's brains once did can result in the loss of true mathematical ability. Recent research suggests that advanced physics students, for example, can often be hampered in their learning by an overreliance on mathematical aids [Source: Bing]. Graphing calculators have even been banned in some classes because of their high memory capability. Students can use their calculators' memory to cheat by storing other information -- like periodic tables or test answers -- in them.

Engineers continue to make advancements in calculator technology, and as they become more and more complex, the lines between personal computers and classic calculators may continue to blur. For their current models, some companies are exploring more ecologically sound components, including the development of more efficient and recyclable power sources, and even using materials like recycled cellular phones in their manufacturing.

Calculators have even moved online and have a number of practical applications. Here are some specific types of calculators you might find online:

  • Weight-loss calculators can measure body mass, caloric content and workout impact.
  • College loan and mortgage calculators that can help you determine the cost and length of a loan according to a wide array of variables.
  • Conversion calculators give you everything from measurements of volume and length to up-to-the-minute currency exchanges.
  • Carbon footprint calculators may help you get an idea of your impact on the environment.


How PCs Work


The word computer refers to an object that can accept some input and produce some output. In fact, the human brain itself is a sophisticated computer, and scientists are learning more about how it works with each passing year. Our most common use of the word computer, though, is to describe an electronic device containing a microprocessor.

A microprocessor is a small electronic device that can carry out complex calculations in the blink of an eye. You can find microprocessors in many devices you use each day, such as cars, refrigerators and televisions. The most recognized device with a microprocessor is the personal computer, or PC. In fact, the concept of a computer has become nearly synonymous with the term PC.

When you hear PC, you probably envision an enclosed device with an attached video screen, keyboard and some type of a pointing device, like a mouse or touchpad. You might also envision different forms of PCs, such as desktop computers, towers and laptops. The term PC has been associated with certain brands, such as Intel processors or Microsoft operating systems. In this article, though, we define a PC as a more general computing device with these characteristics:

  • designed for use by one person at a time
  • runs an operating system to interface between the user and the microprocessor
  • has certain common internal components described in this article, like a CPU and RAM
  • runs software applications designed for specific work or play activities
  • allows for adding and removing hardware or software as needed

PCs trace their history back to the 1970s when a man named Ed Roberts began to sell computer kits based on a microprocessor chip designed by Intel. Roberts called his computer the Altair 8800 and sold the unassembled kits for $395. Popular Electronics ran a story about the kit in its January 1975 issue, and to the surprise of just about everyone, the kits became an instant hit. Thus, the era of the personal computer began [sources: Cerruzi, Lasar].

While the Altair 8800 was the first real personal computer, it was the release of the Apple II a couple of years later that signaled the start of the PC as a sought-after home appliance. The Apple II, from inventors Steve Jobs and Steve Wozniak, proved that there was a demand for computers in homes and schools. Soon after, long-established computer companies like IBM and Texas Instruments jumped into the PC market, and new brands like Commodore and Atari jumped into the game.

In this article, we'll look inside the PC to find out about its parts and what they do. We'll also check out the basic software used to boot and run a PC. Then, we'll cover mobile PCs and examine the future for PC technology.

Core PC Components

To see how a PC works, let's start with the pieces that come together to make up the machine. The following are the components common to PCs in the order they're typically assembled:

Case -- If you're using a laptop, the computer case includes keyboard and screen. For desktop PCs, the case is typically some type of box with lights, vents, and places for attaching cables. The size of the case can vary from small tabletop units to tall towers. A larger case doesn't always imply a more powerful computer; it's what's inside that counts. PC builders design or select a case based on the type of motherboard that should fit inside.

Motherboard -- The primary circuit board inside your PC is its motherboard. All components, inside and out, connect through the motherboard in some way. The other components listed on this page are removable and, thus, replaceable without replacing the motherboard. Several important components, though, are attached directly to the motherboard. These include the complementary metal-oxide semiconductor (CMOS), which stores some information, such as the system clock, when the computer is powered down. Motherboards come in different sizes and standards, the most common as of this writing being ATX and MicroATX. From there, motherboards vary by the type of removable components they're designed to handle internally and what ports are available for attaching external devices.

Power supply -- Other than its CMOS, which is powered by a replaceable CMOS battery on the motherboard, every component in your PC relies on its power supply. The power supply connects to some type of power source, whether that's a battery in the case of mobile computers, or a power outlet in the case of desktop PCs. In a desktop PC, you can see the power supply mounted inside the case with a power cable connection on the outside and a handful of attached cables inside. Some of these cables connect directly to the motherboard while others connect to other components like drives and fans.

Central processing unit (CPU) -- The CPU, often just called the processor, is the component that contains the microprocessor. That microprocessor is the heart of all the PC's operations, and the performance of both hardware and software rely on the processor's performance. Intel and AMD are the largest CPU manufacturers for PCs, though you'll find others on the market, too. The two common CPU architectures are 32-bit and 64-bit, and you'll find that certain software relies on this architecture distinction.

Random-access memory (RAM) -- Even the fastest processor needs a buffer to store information while it's being processed. The RAM is to the CPU as a countertop is to a cook: It serves as the place where the ingredients and tools you're working with wait until you need to pick up and use them. Both a fast CPU and an ample amount of RAM are necessary for a speedy PC. Each PC has a maximum amount of RAM it can handle, and slots on the motherboard indicate the type of RAM the PC requires.

Drives -- A drive is a device intended to store data when it's not in use. A hard drive or solid state drive stores a PC's operating system and software, which we'll look at more closely later. This category also includes optical drives such as those used for reading and writing CD, DVD and Blu-ray media. A drive connects to the motherboard based on the type of drive controller technology it uses, including the older IDE standard and the newer SATA standard.

Cooling devices -- The more your computer processes, the more heat it generates. The CPU and other components can handle a certain amount of heat. However, if a PC isn't cooled properly, it can overheat, causing costly damage to its components and circuitry. Fans are the most common device used to cool a PC. In addition, the CPU is covered by a metallic block called a heat sink, which draws heat away from the CPU. Some serious computer users, such as gamers, sometimes have more expensive heat management solutions, like a water-cooled system, designed to deal with more intense cooling demands.

Cables -- All the components we've mentioned so far are connected by some combination of cables. These cables are designed to carry data, power or both. PCs should be constructed so that the cables fold neatly within the case and do not block air flow throughout it.

A PC is typically much more than these core components. Next, we'll look at the ports and peripherals that let you interact with the computer and how you can add even more components using expansion slots

Ports, Peripherals and Expansion Slots

The core components we've looked at so far make up a PC's central processing power. A PC needs additional components, though, for interacting with human users and other computers. The following are the PC parts that make this happen:

Graphics components -- While somemotherboards have on-board graphics, others include what's called an expansion slot, where you can slide in a separate video card. In both cases, the video components in a PC process some of the complex graphics data going to the screen, taking some of the load off your CPU. A motherboard accepts video cards based on a specific interface, such as the older AGP standard or one of the newer PCI standards.

Ports -- The word port is often used to describe a place on the outside of your PC where you can plug in a cable. Describe a port by its use, such as a USB port or an Ethernet port. (Note that the word port is also used to describe a software connection when two pieces of hardware try to communicate.) Many ports are affixed directly to the motherboard. Some of the ports you'll find on a PC include the following:

  • USB ports
  • network ports, typically Ethernet and FireWire
  • video ports, typically some combination of VGA, DVI, RCA/component, S-Video and HDMI
  • audio ports, typically some combination mini analog audio jacks or RCA
  • legacy ports, or ports that follow old standards which are rarely used in modern computers, such as parallel printer ports and PS2 ports for a keyboard and mouse

Peripherals -- Any piece of hardware that isn't mounted inside a PC's case is called a peripheral. This includes your basic input and output devices: monitors, keyboards and mice. It also includes printers, speakers, headphones, microphones, webcams and USB flash drives. Anything you can plug in to a port on the PC is one of the PC's peripherals. The essential peripherals (such as monitors) aren't necessary on laptops, which have them built in instead.

Expansion slots -- On occasion, you'll want to add components to a PC that don't have a designated slot somewhere on the motherboard. That's why the motherboard will include a series of expansion slots. The removable components designed to fit into expansion slots are called cards, probably because of their flat, card-like structure. Using expansion slots, you can add extra video cards, network cards, printer ports, TV receivers and many other custom additions. The card must match the expansion slot type, whether it's the legacy ISA/EISA type or the more common PCI, PCI-X or PCI Express types.

Now that we've looked at the parts of a PC, let's press the power button and see what makes it boot.

Powering Up a PC

When you first power up a PC, the machine goes through several internal processes before it's ready for you to use. This is called the boot process, or booting the PC. Boot is short for bootstrap, a reference to the old adage, "Pull yourself up by the bootstraps," which means to start something from the very beginning. The boot process is controlled by the PC's basic input-output system (BIOS).

The BIOS is software stored on a flash memory chip. In a PC, the BIOS is embedded on the motherboard. Occasionally, a PC manufacturer will release an update for the BIOS, and you can carefully follow instructions to "flash the BIOS" with the updated software.

Besides controlling the boot process, the BIOS provides a basic configuration interface for the PC's hardware components. In that interface, you can configure such things as the order to read drives during boot and how fast the processor should be allowed to run. Check your PC's documentation to find out how to enter its BIOS interface. This information is often displayed when you first boot the computer, too, with a message such as, "Press DEL to enter Setup Menu."

The following is a summary of the boot process in a PC:

  1. The power button activates the power supply in the PC, sending power to the motherboard and other components.
  2. The PC performs a power-on self-test (POST). The POST is a small computer program within the BIOS that checks for hardware failures. A single beep after the POST signals that everything's okay. Other beep sequences signal a hardware failure, and PC repair specialists compare these sequences with a chart to determine which component has failed.
  3. The PC displays information on the attached monitor showing details about the boot process. These include the BIOS manufacturer and revision, processor specs, the amount of RAM installed, and the drives detected. Many PCs have replaced displaying this information with a splash screen showing the manufacturer's logo. You can turn off the splash screen in the BIOS settings if you'd rather see the text.
  4. The BIOS attempts to access the first sector of the drive designated as the boot disk. The first sector is the first kilobytes of the disk in sequence, if the drive is read sequentially starting with the first available storage address. The boot disk is typically the same hard disk or solid-state drive that contains your operating system. You can change the boot disk by configuring the BIOS or interrupting the boot process with a key sequence (often indicated on the boot screens).
  5. The BIOS confirms there's a bootstrap loader, or boot loader, in that first sector of the boot disk, and it loads that boot loader into memory (RAM). The boot loader is a small program designed to find and launch the PC's operating system.
  6. Once the boot loader is in memory, the BIOS hands over its work to the boot loader, which in turn begins loading the operating system into memory.
  7. When the boot loader finishes its task, it turns control of the PC over to the operating system. Then, the OS is ready for user interaction.

Now that we're all powered up, what's next? A great deal of how PCs work depends on the operating system you use. In the next section, let's examine how operating systems work on a PC.


PC Operating Systems

After a PC boots, you can control it through an operating system, or OS for short. As of this writing, most non-Apple PCs run a version of Microsoft Windows or a Linux distribution. These operating systems are designed to run on various kinds of PC hardware, while Mac OS X is designed primarily for Apple hardware.

An operating system is responsible for several tasks. These tasks fall into the following broad categories:

  • Processor management -- breaks down the processor's work into manageable chunks and prioritizes them before sending them to the CPU.
  • Memory management -- coordinates the flow of data in and out of RAM, and determines when to use virtual memory on the hard disk to supplement an insufficient amount of RAM.
  • Device management -- provides a software-based interface between the computer's internal components and each device connected to the computer. Examples include interpreting keyboard or mouse input or adjusting graphics data to the right screen resolution. Network interfaces, including managing your Internet connection, also fall into the device management bucket.
  • Storage management -- directs where data should be stored permanently on hard drives, solid state drives, USB drives and other forms of storage. For example, storage management tasks assist when creating, reading, editing, moving, copying and deleting documents.
  • Application interface -- provides data exchange between software programs and the PC. An application must be programmed to work with the application interface for the operating system you're using. Applications are often designed for specific versions of an OS, too. You'll see this in the application's requirements with phrases like "Windows Vista or later," or "only works on 64-bit operating systems."
  • User interface (UI) - provides a way for you to interact with the computer.

From there, make a note to see our article How Operating Systems Work for more details about how an OS functions on a PC. Also, check with HowStuffWorks when you want to know how specific applications and devices work on your PC.

Now let's look at the future of PCs overall and the way that PC manufacturers have conquered the portability challenges of mobile computing.


The Future of PCs

Since the first PC hit the market, newer and better models have made older models obsolete within months of production. Drive technologies like SATA replaced IDE, and PCI expansion slots replaced ISA and EISA. The most prominent gauge for technological progress in a PC, though, is its CPU and the microprocessor within that CPU.

Silicon microprocessors have been the heart of the computing world since the 1950s. During that time, microprocessor manufacturers have crammed more transistors and enhancements onto microprocessors. In 1965, Intel founder Gordon Moore predicted that microprocessors would double in complexity every two years. Since then, that complexity has doubled every 18 months, and industry experts dubbed the prediction Moore's Law. Many experts have predicted that Moore's Law will reach an end soon because of the physical limitations of silicon microprocessors [source: PBS].

As of this writing, though, processors' transistor capacities continue to rise. This is because chip manufacturers are constantly finding new ways to etch transistors onto the silicon. The tiny transistors are now measured in nanometers, which is one billionth of a meter. Atoms themselves are approximately 0.5 nm, and the most current production processes for microprocessors can produce transistors that measure 45 nm or 32 nm. The smaller that number goes, the more transistors will fit onto a chip and, thus, the more processing power the chip is capable of. As of May 2011, Intel was working on a 22-nm manufacturing process, code-named Ivy Bridge, which uses transistors with an energy-conserving design called Tri-Gate [sources: BBC, Intel].

So what happens when we reach the end of Moore's Law? A new means of processing data could ensure that progress continues. Potential successors are those that prove to be a more powerful means of performing the basic computational functions of a processor. Silicon microprocessors have relied on the traditional two-state transistor for more than 50 years, but inventions such as quantum computers are changing the game.

Quantum computers aren't limited to the two states of 1 or 0. They encode information as quantum bits, or qubits. A qubit can be a 1 or a 0, or it can exist in a superposition that is simultaneously 1 and 0 or somewhere in between. Qubits represent atoms that are working together to serve as both computer memory and microprocessor. Because a quantum computer can contain these multiple states simultaneously, it has the potential to be millions of times more powerful than today's most powerful supercomputers. Quantum computing technology is still in its early stages, but scientists are already proving the concept with real, measurable results. Be sure to check out How Quantum Computers Work for more on this amazing breakthrough.

Time will tell whether the power of quantum computers will ever make it to the average PC. In the meantime, you can still carry a lot of processing power with you thanks to mobile PCs, which we'll look at next.

Portable Personal Computing

Even before the PC, computer manufacturers were conceptualizing portable computers. It was the 12-pound IBM PC Convertible that brought the laptop concept into production in 1986. Since then, laptop computers have become smaller and lighter, and their processing power has improved alongside desktop PCs [source: IBM].

Today, the computer industry recognizes other classes of mobile computers. One class, the notebook, has become almost synonymous with the laptop. The term was originally used to indicate a smaller, lighter cousin to the laptop. Another class, the netbook, is even smaller than notebooks, while also being cheaper and less powerful. The classification is probably named for its target audience: those that want a very basic interface for using the Internet.

Mobile computing goes even further than notebooks and netbooks. Many smartphones and tablets have as much processing power as notebooks, packed into smaller packages. The key differences include a smaller screen size and resolution, fewer external ports, cellular phone capability and touch-screen technology, in addition to or in place of a keyboard.

On the software side, PC operating systems are also improving portability. For example, Google Chrome OS minimizes the need for hard drive space by relying on access to Web applications and cloud storage. This means a netbook that's limited to a 64 GB solid-state drive has the potential to be as useful as a laptop with a 500 GB disk drive. Naturally, large applications that aren't Web-enabled are the exception to this space-saving advantage.

In this article, we've looked at how a PC works and where PC technology is going. One thing is certain: the PC will evolve. It will get faster. It will have more capacity. And it will continue to be an integral part of our lives.


How Graphics Cards Work


The images you see on yourmonitor are made of tiny dots called pixels. At most common resolution settings, a screen displays over a million pixels, and the computer has to decide what to do with every one in order to create an image. To do this, it needs a translator -- something to take binary data from the CPU and turn it into a picture you can see. Unless a computer has graphics capability built into themotherboard, that translation takes place on the graphics card.

A graphics card's job is complex, but its principles and components are easy to understand. In this article, we will look at the basic parts of a video card and what they do. We'll also examine the factors that work together to make a fast, efficient graphics card.

Think of a computer as a company with its own art department. When people in the company want a piece of artwork, they send a request to the art department. The art department decides how to create the image and then puts it on paper. The end result is that someone's idea becomes an actual, viewable picture.

A graphics card works along the same principles. The CPU, working in conjunction with software applications, sends information about the image to the graphics card. The graphics card decides how to use the pixels on the screen to create the image. It then sends that information to the monitor through a cable. ­

Creating an image out of binary data is a demanding process. To make a 3-D image, the graphics card first creates a wire frame out of straight lines. Then, it rasterizes the image (fills in the remaining pixels). It also adds lighting, texture and color. For fast-paced games, the computer has to go through this process about sixty times per second. Without a graphics card to perform the necessary calculations, the workload would be too much for the computer to handle.

The graphics card accomplishes this task using four main components:

  • A motherboard connection for data and power
  • A processor to decide what to do with each pixel on the screen
  • Memory to hold information about each pixel and to temporarily store completed pictures
  • A monitor connection so you can see the final result

Next, we'll look at the processor and memory in more detail.

The GPU

Like a motherboard, a graphics card is a printed circuit board that houses a processor and RAM. It also has an input/output system(BIOS) chip, which stores the card's settings and performs diagnostics on the memory, input and output at startup. A graphics card's processor, called agraphics processing unit (GPU), is similar to a computer's CPU. A GPU, however, is designed specifically for performing the complex mathematical and geometric calculations that are necessary for graphics rendering. Some of the fastest GPUs have more transistors than the average CPU. A GPU produces a lot of heat, so it is usually located under a heat sink or a fan.

In addition to its processing power, a GPU uses special programming to help it analyze and use data. ATIand nVidia produce the vast majority of GPUs on the market, and both companies have developed their own enhancements for GPU performance. To improve image quality, the processors use:

  • Full scene anti aliasing (FSAA), which smoothes the edges of 3-D objects
  • Anisotropic filtering (AF), which makes images look crisper

Each company has also developed specific techniques to help the GPU apply colors, shading, textures and patterns.

As the GPU creates images, it needs somewhere to hold information and completed pictures. It uses the card's RAM for this purpose, storing data about each pixel, its color and its location on the screen. Part of the RAM can also act as a frame buffer, meaning that it holds completed images until it is time to display them. Typically, video RAM operates at very high speeds and is dual ported, meaning that the system can read from it and write to it at the same time.

The RAM connects directly to the digital-to-analog converter, called the DAC. This converter, also called the RAMDAC, translates the image into an analog signal that the monitor can use. Some cards have multiple RAMDACs, which can improve performance and support more than one monitor. You can learn more about this process in How Analog and Digital Recording Works.

The RAMDAC sends the final picture to the monitor through a cable. We'll look at this connection and other interfaces in the next section.

THE EVOLUTION OF GRAPHICS CARDS

Graphics cards have come a long way since IBM introduced the first one in 1981. Called aMonochrome Display Adapter (MDA), the card provided text-only displays of green or white text on a black screen. Now, the minimum standard for new video cards is Video Graphics Array (VGA), which allows 256 colors. With high-performance standards like Quantum Extended Graphics Array (QXGA), video cards can display millions of colors at resolutions of up to 2040 x 1536 pixels.­


PCI Connection

Graphics cards connect to the computer through the motherboard. The motherboard supplies power to the card and lets it communicate with the CPU. Newer graphics cards often require more power than the motherboard can provide, so they also have a direct connection to the computer's power supply.

Connections to the motherboard are usually through one of three interfaces:

PCI Express is the newest of the three and provides the fastest transfer rates between the graphics card and the motherboard. PCIe also supports the use of two graphics cards in the same computer.

Most graphics cards have two monitor connections. Often, one is a DVI connector, which supports LCDscreens, and the other is a VGA connector, which supports CRT screens. Some graphics cards have two DVI connectors instead. But that doesn't rule out using a CRT screen; CRT screens can connect to DVI ports through an adapter. At one time, Apple made monitors that used the proprietary Apple Display Connector (ADC). Although these monitors are still in use, new Apple monitors use a DVI connection.

Most people use only one of their two monitor connections. People who need to use two monitors can purchase a graphics card with dual head capability, which splits the display between the two screens. A computer with two dual head, PCIe-enabled video cards could theoretically support four monitors.

In addition to connections for the motherboard and monitor, some graphics cards have connections for:

Some cards also incorporate TV tuners. Next, we'll look at how to choose a good graphics card.

DIRECTX AND OPEN GL

DirectX and Open GL are application programming interfaces, or APIs. An API helps hardware and software communicate more efficiently by providing instructions for complex tasks, like 3-D rendering. Developers optimize graphics-intensive games for specific APIs. This is why the newest games often require updated versions of DirectX or Open GL to work correctly.

APIs are different from drivers, which are programs that allow hardware to communicate with a computer's operating system. But as with updated APIs, updated device drivers can help programs run correctly.­


Choosing a Good Graphics Card

A top-of-the-line graphics card is easy to spot. It has lots of memoryand a fast processor. Often, it's also more visually appealing than anything else that's intended to go inside a computer's case. Lots of high-performance video cards are illustrated or have decorative fans or heat sinks.

But a high-end card provides more power than most people really need. People who use their computers primarily for e-mail, word processing or Web surfing can find all the necessary graphics support on a motherboard with integrated graphics. A mid-range card is sufficient for most casual gamers. People who need the power of a high-end card include gaming enthusiasts and people who do lots of 3-D graphic work.

A good overall measurement of a card's performance is its frame rate, measured in frames per second (FPS). The frame rate describes how many complete images the card can display per second. The human eye can process about 25 frames every second, but fast-action games require a frame rate of at least 60 FPS to provide smooth animation and scrolling. Components of the frame rate are:

  • Triangles or vertices per second: 3-D images are made of triangles, or polygons. This measurement describes how quickly the GPU can calculate the whole polygon or the vertices that define it. In general, it describes how quickly the card builds a wire frame image.
  • Pixel fill rate: This measurement describes how many pixels the GPU can process in a second, which translates to how quickly it can rasterize the image.

The graphics card's hardware directly affects its speed. These are the hardware specifications that most affect the card's speed and the units in which they are measured:

  • GPU clock speed (MHz)
  • Size of the memory bus (bits)
  • Amount of available memory (MB)
  • Memory clock rate (MHz)
  • Memory bandwidth (GB/s)
  • RAMDAC speed (MHz)

The computer's CPU and motherboard also play a part, since a very fast graphics card can't compensate for a motherboard's inability to deliver data quickly. Similarly, the card's connection to the motherboard and the speed at which it can get instructions from the CPU affect its performance.

For more information on graphics cards and related topics, check out the links on the following page.

INTEGRATED GRAPHICS AND OVERLOCKING

Many motherboards have integrated graphics capabilities and function without a separate graphics card. These motherboards handle 2-D images easily, so they are ideal for productivity and Internet applications. Plugging a separate graphics card into one of these motherboards overrides the onboard graphics functions.

Some people choose to improve their graphics card's performance by manually setting their clock speed to a higher rate, known as overclockings. People usually overclock their memory, since overclocking the GPU can lead to overheating. While overclocking can lead to better performance, it also voids the manufacturer's warranty.


Why are there dozens of dead animals floating in space?


On July 20, 1969, Neil Armstrong became the first man in history to step on the surface of the moon. Millions of people tuned in to a broadcast of the event, and after Edwin "Buzz" Aldrin, Jr. joined Armstrong, the two spent about two and a half hours gathering lunar rocks to bring back for analysis. The success was a triumph, not just for the United States, but for mankind, the imagination and the possibilities of exploration.

What many people don't know, however, are the special sacrifices that had to be made in order to get astronauts up into space at all. The major unsung heroes of space exploration, it turns out, are animals.

Before space programs started sending people up into orbit, scientists couldn't agree on what it would be like for a living organism to leave Earth's atmosphere. What would be the effects ofweightlessness on a mammal? How would the body handle radiation from the sun? Instead of sending people up in such a risky situation, the United States and Russia sent monkeys, chimps, dogs and other animals into space in order to analyze such effects.

Unfortunately, since it was so early on in the space race, the design process for constructing the vehicles was trial and error -- if launches or reentry procedures were faulty, the animals had little chances of survival. In some cases, the spacecraft in which the animals flew were never recovered, leading many to suspect there are still several abandoned ships floating in orbit among space junk with their original furry cargo.

To learn more about animals in space and how they helped scientists learn more about space exploration, see below...

Early Animals in Space

The first living organisms to make it into space and back were actually much smaller than a monkey or a dog -- in 1947, a container full of fruit flies successfully flew 106 miles above the Earth and parachuted back without any apparent damage.

Soon after that, space programs began sending up larger animals. The next year, the Aero Medical Laboratory began conducting animal experiments in White Sands, N.M., and on June 11, 1948, a V-2 Blossom rocket launched into space with Albert I, a rhesus monkey. Because of close quarters, Albert died of suffocation during the flight. By naming the monkey Albert, the scientists started a trend, since every monkey used during the operation was called Albert, and the entire endeavor is now known as the Albert Project. They unfortunately also continued a trend of failure -- most of the launches experienced major technical difficulties and animal fatalities. The best that could be said was that the second monkey, Albert II, survived his entire flight through space, only to die during reentry.

More missions throughout the '50s offered more improvements, but the most famous and beloved of space animals is Laika. A month after the Soviet Union stunned the world with the launch of Sputnik I, the first satellite to enter orbit, the Russians revealed an even more shocking plan. On Nov. 3, 1957, Sputnik 2 launched, but this time a live dog named Laika (Russian for "Barker") was on board. Originally named Kudryavka (or "Little Curly") by the trainers, Laika was a 13-pound, part-Samoyed mongrel female from the streets of Russia -- strays were preferred for spaceflight because of their strength and their ability to survive in cold temperatures.

Laika in Sputnik II before takeoff. Her last meal on the flight was poisoned to prevent her dying a slow death of starvation. However, she died of panic and suffocation within hours of takeoff.

Keystone/Getty Images

Unfortunately, the flurry of press over Sputnik I caused Nikita Khrushchev, head of theCommunist Party, to rush Sputnik 2 to launch for the one-month "anniversary" of Sputnik I, and designs for the new satellite were very poor. The Soviets even admitted soon after the launch that Laika wouldn't return home, and the satellite itself burned up in reentry. Officials led people to believe the dog survived in orbit for as long as four days before she died from overheating. In 2002, however, evidence revealed Laika actually passed away just a few hours after the launch from a combination of heat and panic. Laika's death encouraged Americans to talk more openly about the treatment of animals, and the Russian people looked down upon Sputnik 2 as an unfortunate attempt at propaganda.







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