Water Purification Process

NatureSkills.com exclusive! Note: also make sure you view the Giardia article “Water, water everywhere and not a drop to drink,” as the old saying goes. A more apt statement for these times might be, “water, water everywhere, but is it safe to drink?” Sadly, in this day and age there are few, if any, places where the water is safe to drink without treating, no matter how pristine and inviting it may look. Water in the wild often contains harmful microorganisms, bacteria and parasites that can cause a variety of ailments, such as giardia, dysentery, hepatitis, and hookworms. Luckily, however, there are many simple and diverse methods to treat water to make it safe for consumption. I. Water Purification Process: boiling The simplest method to purify water is probably boiling. You need to bring the water to a full, rolling boil for at least five minutes to be safe, with some experts recommending an even longer time. The down side to boiling your drinking water is that it removes the oxygen and the water ends up tasting flat. You can improve its quality by pouring it back and forth between two containers to put oxygen back in, or simply shake it up. II. Water Purification Process: purifiers There are also several chemical purifiers on the market. Iodine comes in either liquid form, (which can be messy), or tablet form. One to two tablets or drops will clear up a quart of water.  Shake your container and wait twenty minutes before drinking. Water treated with iodine will have a darker color and a bit of an unpleasant flavor.  It is possible to mask this flavor by adding a powdered drink mix, but be sure to wait the twenty minutes before adding it, as it will interfere with the iodine’s effectiveness. Other chemical treatments that work similarly to iodine are chlorine tablets, potassium permanganate, or halazone tablets. You should be able to pick these up fairly cheaply at most outdoor stores. You can even add a few drops of bleach in a pinch, though I wouldn’t recommend overusing this one. It is important when using chemical purification to make sure all surfaces have been decontaminated. After waiting the twenty minutes, slightly unscrew the lid of your water bottle or container and rinse around the threads and lid. The nice thing about using tablets is the container is very small and portable and can be slipped into a pocket, a plus if you do not want to carry a stove or pot, or take the time to boil water. Chemical treatment can be done on the hoof with minimal stopping time. III. Water Purification Process: filters A third method of treatment is commercial filters. These come in all shapes, sizes and price ranges. Most work by pushing the water through a charcoal or ceramic filter and then chemically treating it. Normally, they have one hose with a float that goes from the water source to the filter and a second hose, for clean water, that goes from filter to water bottle. When using this type of filter it is important to not cross contaminate the hoses. Keep the clean hose in a separate plastic bag so it never touches the contaminated hose. The plus side, no flat or funky flavor. Commercial filters are also good for when the water is on the murky or dirty side, as they will remove this also. The drawback is that the sediment or tannins that you are filtering out will quickly clog up the filter. Some can be cleaned, with others you need to buy a replacement filter. Like all technical equipment, cost and breakage are things to be considered. IV. Water Purification Process: primitive methods Beyond these common methods, there are more primitive techniques for the serious survivalists (or the unlucky person who was caught unprepared). One is filtering through soil or, preferably, sand. Keep rinsing the water repeatedly through the sand until it is looking clear. A variation of this is to dig a hole near where the source is and use the water that filters through into the hole. Be aware, that although soil is a good filter for sediment and other particles, it is not a guarantee for things like bacteria. This is even true for spring water, which many people assume is safe to drink without treatment. Distilling is a method that can be used for either collecting water or gathering fresh water out of salt water. To collect water from the ground, dig a deep hole and place a collecting container in the center. Cover the hole with a clear sheet of plastic. The plastic needs to be weighted in the center with a rock or heavy object so that it points down into the container. Then, secure the sides of the plastic tightly around the hole, such as by covering with dirt. The clear plastic acts like a greenhouse. The water in the soil evaporates as it heats up. When it hits the plastic it runs down to the point and drips off into the container. If all you have is salt water, you can distill it by placing a small pot inside a larger pot. The salty water goes in the larger pot but not the smaller one. Invert a lid over the pots that will point down into the smaller pot, then bring the water to a boil. As the water boils, fresh water will evaporate, hit the lid and drip down into the smaller pot, leaving the salt, or other minerals behind. An alternative if you don’t have a smaller pot is to put a cloth over the pot the will absorb the steam. Use caution when removing it to wring it out so you don’t get burned. Above all, be cautious and use common sense when choosing where to gather your water. Do the plants surrounding it look healthy? Are there dead animals near by that might have contaminated it? Don’t collect any water that looks stagnant. Generally, water that is further upstream will be cleaner than that downstream, but there are no guarantees. Don’t automatically go for the fasting rushing water, as fast water carries more sediment. You can avoid picking up a lot of sediment by making sure you dunk your water bottle completely under the water. This will avoid all the dirt and debris that floats on the surface. With so many ways to purify water, there should be something for everyone and no reason to ever take chances drinking untreated water. There are die-hards out there who will argue that the risk is small and not worth worrying about. But a nasty case of beaver fever in the back country can be not only uncomfortable, but life threatening. Diarrhea and vomiting can cause serious dehydration and sap your strength to the point that you can get yourself to safety.             If you are going to spend time in the outdoors, always make sure you have at least one, if not two or more, methods for purifying water. It's vital to know water purification process methods.

Software Engineer

A software engineer is in charge of assembling extensive amounts of code into working applications, as well as updating and fixing problems in existing software. A software engineer is also referred to as a programmer, because the main duties of asoftware engineer involve programming computers. Software engineering may be compared with computer science. While asoftware engineer works on actually developing working software solutions, a computer scientist focuses on the theoretical construct of software and hardware development.There is some debate over whether a software engineer should rather be referred to as a developer or programmer, because of connotations held by the term engineer. Many charge that software development is not held to the same rigorous and exacting standards as fields such as electrical engineering, and therefore should not be associated with other, more strict forms ofengineering. The title of software engineer, as a result of these controversies, is bestowed rather haphazardly. The industry itself has not yet come up with widely agreed upon practices for licensing software engineers —- something other engineeringdisciplines have —- and so even a person without formal training may be referred to as a software engineer.There are estimated to be over two-and-a-half million software engineers worldwide, a number less than, but rapidly approaching, that of traditional engineers. The role of software engineers in society is expanding as computers and their applications become more pervasive. Economically, socially and politically, computers are changing the world everywhere they reach, and softwareengineers are building the tools that drive that change
Only about one-half of software engineers in the industry hold a degree of some level in computer science, and less than five percent hold a degree specifically in software engineering. These numbers are growing, as the marketplace becomes more competitive and entry-level software engineers struggle to distinguish themselves. A number of graduate programs exist for both computer science and software engineering, as well, though these degrees are often acquired after some years of experience in the field.

Difference between a programmer and a Software Enginee

 Fundamentally there is little difference as both write software. Software Engineers are programmers but it's how they do the job that differs.

Read about software

Is it all Paperwork?

Software Engineering is an approach to developing software that attempts to treat it as a formal process more like traditional engineering than the craft that many programmers believe it is. We talk of crafting an application, refining and polishing it, as if it were a wooden sculpture, not a series of logic instructions. The problem here is that you cannot engineer art. Programming falls somewhere between an art and a science.

Programming - Art or Engineering?

There has always been considerable debate about the nature of programming. If bridges were designed like software then there would be a lot of ferries operating. You can't have a second go if a bridge fails. That's the argument that the Software Engineering proponents put forward.

Am I a Designer or Engineer?

I don't quite accept this argument as it's comparing chalk and cheese. Computer programs are very complex pieces of logic. In a bridge, the main load bearing members are well defined and the design takes into account the strength and thickness of the materials used. Any reasonable sized application may have ten thousand branch points, so the number of execution paths through this application is a very large number. Testing all those paths is a difficult task.

How do I Stop my Software Killing Someone?

Manufacturers cannot build complex life-critical systems like aircraft, nuclear reactor controls, medical systems and expect the software to be thrown together. They require the whole process to be thoroughly managed, so that budgets can be estimated, staff recruited, and to minimize the risk of failure or expensive mistakes.

In safety critical areas such as aviation,space, nuclear power plants,medicine, fire detection systems, and roller coaster rides the cost of failure can be enormous as lives are at risk. A divide by zero error that brings down an aircraft is just not acceptable.

So It Never Goes Wrong?

In spite of this there have been a few high profile disasters. Ariane 5, a rocket system for delivering satellites into orbit blew up in June 1996, 40 seconds after takeoff due to an arithmetic overflow bug. The system had used specifications from an earlier rocket Ariane 4 without having been fully tested.

What Is Computer Aided Software Engineering?

The whole design process has to be formally managed long before the first line of code is written. Enormous design documents- hundreds or thousands of pages long are produced using C.A.S.E. (Computer Aided Software Engineering) tools then converted into Design Specification documents which are used to design code.

C.A.S.E suffers from the "not quite there yet" syndrome. There are no systems that can take a set of design constraints and requirements then generate code that satisfies all the requirements and constraints. Its far too complex a process. So the available C.A.S.E. systems manage parts of the lifecycleprocess but not all of it.

So it is Paper Work?

One distinguishing feature of Software Engineering is the paper trail that it produces. Designs have to be signed off by Managers and Technical Authorities all the way from top to bottom and the role of Quality Assurance is to check the paper trail. Many Software Engineers would admit that their job is around 70% paperwork and 30% code. It's a costly way to write software and this is why avionics in modern aircraft are so expensive.

Call Yourself an Engineer?

Note. In some parts of the world (and some U.S. States) you cannot call yourself a software engineer without a formal qualification.

If you want to become a software engineer, the first step is to learn a programming language and you are in the right place! Try one of our tutorials- heres a selection!

CD/DVD-ROM Drive

• CD-ROM drives are necessary today for most programs. A single CD can store up to 650 MB of data (newer CD-Rs allow for 700 MB of data, perhaps more with "overburn"). Fast CD-ROM drives have been a big topic in the past, but all of today's CD-ROM drives are sufficiently fast. Of course, it's nice to have the little bits of extra speed. However, when you consider CD-ROM drives are generally used just to install a program or copy CDs, both of which are usually done rarely on most users' computers, the extra speed isn't usually very important.  The speed can play a big role if you do a lot of CD burning at high speeds or some audio extraction from audio CDs (i.e. converting CDs to MP3s).
• CD-R/RW (which stands for Recordable / ReWritable) drives (aka burners, writers) allow a user to create their own CDs of audio and/or data.  These drives are great for backup purposes (backup your computer's hard drive or backup your purchased CDs) and for creating your own audio CD compilations (not to mention other things like home movies, multimedia presentations, etc.).
• DVD-ROM drives can store up to 4 GB of data or about 6 times the size of a regular CD (not sure on the exact size, but suffice to say it's a very large storage medium).  DVDs look about the same and are the same size as a CD-ROM. DVD drives can also read CD-ROM drives, so you don't usually need a separate CD-ROM drive. DVD drives have become low enough inprice that there isn't much point in purchasing a CD-ROM drive instead of a DVD-ROM drive.  Some companies even make CD burner drives that will also read DVDs (all in one).  DVD's most practical use is movies. The DVD format allows for much higher resolution digital recording that looks much clearer than VCR recordings. 
• DVD recordable drives are available in a couple of different formats - DVD-R or DVD+R with a RW version of each. These are slightly different discs and drives (although some drives support writing to both formats).  One is not much better than the other, so it really boils down to price of the media (and also availability of the media). 

Monitors Resolution

Imagine lying down in the grass with your nose pressed deep into the thatch. Your field of vision would not be very large, and all you would see are a few big blades of grass, some grains of dirt, and maybe an ant or two. This is a 14-inch 640 x 480 monitor. Now, get up on your hands and knees, and your field of vision will improve considerably: you'll see a lot more grass. This is a 15-inch 800 x 640 monitor. For a 1280 x 1024 perspective (on a 19-inch monitor), stand up and look at the ground. Some monitors can handle higher resolutions such as 1600 x 1200 or even 1920 x 1440—somewhat akin to a view from up in a tree.
Monitors are measured in inches, diagonally from side to side (on the screen). However, there can be a big difference between that measurement and the actual viewable area. A 14-inch monitor only has a 13.2-inch viewable area, a 15-inch sees only 13.8 inches, and a 20-inch will give you 18.8 inches (viewing 85.7% more than a 15-inch screen).
A computer monitor is made of pixels (short for "picture element"). Monitor resolution is measured in pixels, width by height. 640 x 480 resolution means that the screen is 640 pixels wide by 480 tall, an aspect ratio of 4:3. With the exception of one resolution combination (1280 x 1024 uses a ratio of 5:4), all aspect ratios are the same.
From The PC Guide, by Charles M. Kozierok:

A pixel is the smallest element of a video image, but not the smallest element of a monitor's screen. Since each pixel must be made up of three separate colors, there are smaller red, green, and blue dots on the screen that make up the image. The term dot is used to refer to these small elements that make up the displayed image on the screen. In order to use different resolutions on a monitor, the monitor must be able to support automatic changing of resolution modes. Originally, monitors were fixed at a particular resolution, but most monitors today are capable of changing their displayed resolution under software control. This allows for higher or lower resolution depending on the needs of the application. A higher resolution display shows more on the screen at one time, and the maximum resolution that a monitor can display is limited by the size of the monitor and the characteristics of the CRT (cathode-ray tube). In addition, the monitor must have sufficient input bandwidth to allow for refresh of the screen, which becomes more difficult at higher resolutions because there is so much more information being sent to the monitor.

You can see by the chart below how screen size and effective resolution are linked. Compare a 15-inch monitor and a 21-inch monitor, both set to 800 x 600 pixels: the 15-inch will have a higher resolution. Larger monitors must contain smaller pixels in order to maintain the same resolution, but when a smaller monitor is set to a high resolution, the images would be much too small to read. A 14-inch monitor set to 640 x 480 is very readable, while a 21-inch needs at least 1024 x 768. Here are some recommended resolutions for the different screen sizes:

	14"	15"	17"	19"	21"
640x480	BEST	GOOD	TOO BIG	HUGE	TERRIBLE
800x600	GOOD	BEST	GOOD	TOO BIG	HUGE
1024x768	TOO SMALL	GOOD	BEST	GOOD	STILL GOOD
1280x1024	TINY	TOO SMALL	GOOD	BEST	GOOD
1600x1200	TERRIBLE	TINY	TOO SMALL	GOOD	BEST

TheScreamOnline is optimized for viewing at 1024 x 768 resolution.
As you can see by the chart above, it should look good on most monitors.
Be aware that there are many versions and interpretations of these settings.
This table is an average of various opinions.

Adjusting Resolution

On a PC with Windows, do the following:

1. Double-click the Display Icon in the Control Panel by clicking: Start > Settings > Control Panel.
2. Select the "Settings" tab in the Display Properties Dialog Box.
3. Adjust the slider to 800 x 600 (shown below), then click the Test Button. A test bitmap will appear for 5 seconds, then you will be asked if everything looked OK. Click YES to confirm.

On a Mac, go to Control Panels > Monitors and you will see a list of settings. It couldn't be easier.

Color

From The PC Guide, by Charles M. Kozierok

There are 4 standard color depths used by monitors: 4-bit (Standard VGA), 8-bit (256-Color Mode), 16-bit (High Color),and 24-bit (True Color). Each pixel of the screen image is displayed using a combination of three different color signals: red, green, and blue. The appearance of each pixel is controlled by the intensity of these three beams of light. When all are set to the highest level the result is white; when all are set to zero the pixel is black. The amount of information that is stored about a pixel determines its color depth, which controls how precisely the pixel's color can be specified. This is also sometimes called the bit depth, because the precision of color depth is specified in bits. The more bits that are used per pixel, the finer the color detail of the image. However, increased color depths also require significantly more memory for storage of the image, and also more data for the video card to process, which reduces the possible maximum refresh rate.

[Computers use a binary language of two numbers, "one" and" zero," signifying "on" and "off." Bit depth is the number of bits in each pixel. Color depth is the maximum number of colors in an image and is based on the bit depth of the image and of the displaying monitor. A black and white monitor uses 1-bit color depth (2 to the power of 1): black=light off, and white= light on. Each pixel has a bit depth of one and a color depth of two. One bit produces two possible colors. Color monitors use at least 2-bit color, or 2-to-the-2nd power (2x2=4), meaning that 4 shades of color are available for each of the three primary colors (red, blue, and green). 4-bit color (2x2x2x2=16) means that each of the primaries has 16 shades; the greater the bit depth, the more shades for each color. See the chart below for a comparison of bit depth and color resolution. —Ed.]

256-Color Mode: uses only 8 bits (2 bits for blue, 3 for green, 3 for red). Choosing between only 4 or 8 different values for each color would result in poor blocky color, so a different approach is taken instead: the use of a palette. A palette is created containing 256 different colors. Each one is defined using the standard 3-byte color definition that is used in true color: 256 possible intensities for each of red, blue, and green. Each pixel is allowed to choose one of the 256 colors in the palette, which can be considered a "color number" of sorts. So the full range of color can be used in each image, but each image can only use 256 of the available 16 million different colors. When each pixel is displayed, the video card looks up the real RGB values in the palette based on the "color number" the pixel is assigned.
The palette approach is an excellent compromise: it allows only 8 bits to be used to specify each color in an image, but allows the creator of the image to decide what the 256 colors in the image should be. Since virtually no images contain an even distribution of colors, this allows for more precision in an image by using more colors than would be possible by assigning each pixel a 2-bit value for blue and 3-bit values each for green and red. For example, an image of the sky with clouds would have many different shades of blue, white, and gray, and virtually no reds, greens, or yellows.
256-color is the standard for much of computing, mainly because the higher-precision color modes require more resources (especially video memory) and aren't supported by many PC's. Despite the ability to "hand pick" the 256 colors, this mode produces noticeably worse image quality than high color, and most people can tell the difference between high color and 256-color mode.
High color: 16-bit color—uses two bytes of information to store the intensity values for the three colors. This is done by breaking the 16 bits into 5 bits for blue, 5 bits for red, and 6 bits for green, giving 32 different intensities for blue, 32 for red, and 64 for green. This reduced color precision results in a slight loss of visible image quality, but it is actually very slight—most people cannot see the differences between true color and high color images unless they are looking for them. For this reason high color is often used instead of true color—it requires 33% (or 50% in some cases) less video memory, and it is also faster for the same reason.
True color: 24-bit color—three bytes of information are used, one for each of the red, blue, and green signals that make up each pixel. Since a byte has 256 different values, each color can have 256 different intensities, using over 16 million different color possibilities, and allowing for a very realistic representation of the color of images, with no compromises necessary and no restrictions on the number of colors an image can contain. In fact, 16 million colors is more than the human eye can discern, though true color is necessary for doing high-quality photo editing, graphic design, etc. [Some video cards have to use 32 bits of memory for each pixel when operating in true color, due to how they use the video memory.]

[TheScreamOnline is best viewed with 24-bit color, or millions of colors, though thousands of colors will suffice. On a Mac, go to Control Panels > Monitors (see graphic above under Adjusting Resolution) and set the color depth to thousands or millions of colors if your video card supports it. Lowering the resolution of your screen display may allow you to achieve a greater color depth. On a Windows computer, go to Start Menu > Settings > Control Panels > Display > Settings. —Ed.]

BIT DEPTH	COLOR RESOLUTION	CALCULATION
1-bit	2 colors	2 (2)
2-bit	4 colors	2 (2x2)
3-bit	8 colors	2 (2x2x2)
4-bit	16 colors	2 (2x2x2x2)
5-bit	32 colors	2 (2x2x2x2x2)
6-bit	64 colors	2 (2x2x2x2x2x2)
7-bit	128 colors	2 (2x2x2x2x2x2x2)
8-bit	256 colors	2 (2x2x2x2x2x2x2x2)
16-bit	65,536 colors	2
24-bit	16,777,215 colors	2

Monitors vs. Browsers

Four variables tend to make the life of a web designer a living hell. Macintosh monitors display text at 72 dpi (dots-per-inch) and PC's take 96 pixels to show that same text. Translation: a PC monitor enlarges the type—sort of like reading a large-print novel. Differences in the two major browsers (Netscape and Internet Explorer) also add to the problem. Netscape is close to WYSIWYG (What You See Is What You Get)—it doesn't significantly change how a webpage is meant to appear. Internet Explorer (or IE), on the other hand, enlarges text one-to-two point sizes. So, a page of text can appear four different ways, depending on the combination: Netscape on a Mac, IE on a Mac, Netscape on a PC, and IE on a PC. The difference between viewing a page on a Mac using the Netscape browser and that same page on a PC with IE is enormous.
A lot of seemingly unnecessary time is spent by web designers trying to "dumb-down" a site so that it looks acceptable in all formats. Many designers, however, say "To hell with those with cheap equipment," and create a site for users with high-end gear. If only the two platforms and browsers could conform to a standard, then most of these woes wouldn't exist and not only could designers focus more on the quality of the design itself, the product would be better and the end-user (you!) would consistently see websites as they were meant to be viewed.

Caveat Emptor

Many of the low-price "deals" that come with PC packages can include—in addition to the requisite monitor, CPU, and keyboard—a modem, scanner, Zip drive, printer, and CD-rom drive. Be careful—you get what you pay for. Much of the time you will end up with a very inexpensive 8-bit 640 x 480 monitor that cannot be adjusted. While a good monitor (large size with a high resolution/bandwidth/refresh rate and small dot pitch) will hold its value for some time, CPU's will be worth only a fraction of their original cost after about a year. If you just use a computer for basic word-processing and email communications, then the cheap route is probably adequate. Beyond that, you will quickly realize the limitations of your purchase. If you are serious about creating, or at least viewing, high-quality images, in addition to viewing websites as they are meant to be seen, then it would be wise to invest in the appropriate equipment.

Motherboard

The motherboard is the most essential component in a personal computer . it is the piece of hardware which contains the computer's micro-processing chip and everything attached to it is vital to making the computer run.

Motherboard Components

If you open your computer's case, the motherboard is the flat, rectangular piece of circuit board to which everything seems to connect to for one reason or another. It contains the following key components:

• A microprocessor "socket" which defines what kind of central processing unit the motherboard uses;
• A chipset which forms the computer's logic system. It is usually composed of two parts called bridges (a "north" bridge and its opposite, "south" bridge), which connects the CPU to the rest of the system;
• A Basic Input/Output System (BIOS) chip which controls the most basic function of a computer, and how to repair it; and
• A real-time clock which is a battery-operated chip which maintains the system's time, and other basic functions.

The motherboard also has slots or ports for the attachment of various peripherals or support system/hardware. There is an Accelerated Graphics Port, which is used exclusively for video cards; Integrated Drive Electronics, which provides the interfaces for the hard disk drives; Memory or RAM cards; and Peripheral Component Interconnect (PCI), which provides electronic connections for video capture cards and network cards, among others.

How a Motherboard Works

The most important thing to remember about the motherboard is that it is a printed circuit board which provides all the connections, pathways and "lines" connecting the different components of the computer to each other – specifically, the Central Processing Unit or CPU, which is where (as its name implies) all the "processing" is going on to everything else.

The CPU or "chip" (the most popular of which is Intel's Pentium series) is an assembly of transistors and other devices (Pentium IV has over 4 million transistors) which perform or processes myriad programmed tasks.

The CPU rests in a "socket" on the motherboard which is connected to the other components through the board's printed circuits. The most important connections are to the chipsets – especially the northbridge chipset which is connected to the main computer memory (hard disk and RAM), while the southbridge set is connected to the peripherals – video and audio cards, IDE controllers, etc.

Aside from these, the most important element of the motherboard is the BIOS chip – which performs key functions like checking power supply, the hard disk drive, operating system, etc. before the computer actually starts "booting up". Turning on the computer automatically starts the BIOS chip up to perform its diagnostic functions, after which it powers up the CPU which – in its turn – starts powering up the other peripherals (hard disk, operating system, video and audio, etc.).

This is why the motherboard is the key component of the computer. It is, in effect, the "housing" for the CPU – the place where the latter resides and from which commands, instructions, and power course through before being sent out to other components.

3D Video Cards

The new market for 3D accelerators and 3D acceleration features has spawned a large crop of 3D video cards with varying capabilities. There are several different approaches that are taken to providing a system with 3D capabilities. While the available cards and technologies are changing rapidly, you will generally find that the cards on the market break out as follows:

• 2D Only (Conventional) Cards: These are regular video cards that do not incorporate any special 3D acceleration functions. Usually these are either older cards, or newer cards that are optimized for 2D performance. When using a card of this type, it is necessary to pair it with a 3D card to obtain 3D acceleration functions.
• Dedicated 3D Cards: These are accelerators that are designed only for 3D hardware functions. Since they do not do conventional 2D acceleration, they need to work with a 2D card in most cases to deliver good 2D+3D performance. Most of the higher-quality 3D cards are of this variety. They typically use a feature connector to connect directly to the 2D card. This lets the 3D card perform its acceleration functions to provide a video stream without requiring its own RAMDAC or bus control logic. This is generally the best solution for high-end graphics but it incurs the cost of two video cards.
• Combination 2D+3D Cards: In an effort to tackle the cost problem of using an additional, separate card for 3D acceleration, many companies are developing cards that perform both 2D and 3D functions. For many users, this is a good, cost-effective compromise. Most of these cards provide from moderate to good 2D performance, and support for some to most of the 3D acceleration features. However, like most compromises, these cards typically don't provide the level of performance or feature support that dedicated 3D cards do. It is important to research these cards well, since many of them support only a small subset of the 3D acceleration features found on 3D cards.

What is a hard drive

A hard drive is a mass storage device found in all PCs (with some exclusions) that is used to store permanent data such as the operating system, programs and user files. The data on hard drives can be erased and/or overwritten. The hard drive is classed as a non-volatile storage device, which means it doesn't require a constant power supply in order to retain the information stored on it (unlike RAM).

Inside every hard drive are small round disk-like objects made of either an aluminium/alloy or a glass/ceramic composite. These are called platters, each platter is coated with a special magnetic coating enabling them to store data magnetically. Hovering above these platters are read/write heads that transfer data to and from the platters. We will cover platters, heads and the other mechanical elements in more detail in the hard drive mechanics section.

Computer Processor

The processor (CPU, for Central Processing Unit) is the computer's brain. It allows the processing of numeric data, meaning information entered in binary form, and the execution of instructions stored in memory. 

The first microprocessor (Intel 4004) was invented in 1971. It was a 4-bit calculation device with a speed of 108 kHz. Since then, microprocessor power has grown exponentially. So what exactly are these little pieces of silicone that run our computers? 

Operation

The processor (called CPU, for Central Processing Unit) is an electronic circuit that operates at the speed of an internal clock thanks to a quartz crystal that, when subjected to an electrical currant, send pulses, called "peaks". The clock speed (also called cycle), corresponds to the number of pulses per second, written in Hertz (Hz). Thus, a 200 MHz computer has a clock that sends 200,000,000 pulses per second. Clock frequency is generally a multiple of the system frequency (FSB, Front-Side Bus), meaning a multiple of the motherboard frequency. 

With each clock peak, the processor performs an action that corresponds to an instruction or a part thereof. A measure called CPI (Cycles Per Instruction) gives a representation of the average number of clock cycles required for a microprocessor to execute an instruction. A microprocessor’s power can thus be characterized by the number of instructions per second that it is capable of processing. MIPS(millions of instructions per second) is the unit used and corresponds to the processor frequency divided by the CPI.

Instructions

An instruction is an elementary operation that the processor can accomplish. Instructions are stored in the main memory, waiting to be processed by the processor. An instruction has two fields:

• the operation code, which represents the action that the processor must execute;
• the operand code, which defines the parameters of the action. The operand code depends on the operation. It can be data or a memory address.

Operation Code

Operand Field

The number of bits in an instruction varies according to the type of data (between 1 and 4 8-bit bytes). 

Instructions can be grouped by category, of which the main ones are:

• Memory Access: accessing the memory or transferring data between registers.
• Arithmetic Operations: operations such as addition, subtraction, division or multiplication.
• Logic Operations: operations such as AND, OR, NOT, EXCLUSIVE NOT, etc.
• Control: sequence controls, conditional connections, etc.

Registers

When the processor executes instructions, data is temporarily stored in small, local memory locations of 8, 16, 32 or 64 bits called registers. Depending on the type of processor, the overall number of registers can vary from about ten to many hundreds. 

The main registers are:

• the accumulator register (ACC), which stores the results of arithmetic and logical operations;
• the status register (PSW, Processor Status Word), which holds system status indicators (carry digits, overflow, etc.);
• the instruction register (RI), which contains the current instruction being processed;
• the ordinal counter (OC or PC for Program Counter), which contains the address of the next instruction to process;
• the buffer register, which temporarily stores data from the memory.

Cache Memory

Cache memory (also called buffer memory) is local memory that reduces waiting times for information stored in the RAM (Random Access Memory). In effect, the computer's main memory is slower than that of the processor. There are, however, types of memory that are much faster, but which have a greatly increased cost. The solution is therefore to include this type of local memory close to the processor and to temporarily store the primary data to be processed in it. Recent model computers have many different levels of cache memory:

• Level one cache memory (called L1 Cache, for Level 1 Cache) is directly integrated into the processor. It is subdivided into two parts:
  • the first part is the instruction cache, which contains instructions from the RAM that have been decoded as they came across the pipelines.
  • the second part is the data cache, which contains data from the RAM and data recently used during processor operations.

Level 1 caches can be accessed very rapidly. Access waiting time approaches that of internal processor registers.

• Level two cache memory (called L2 Cache, for Level 2 Cache) is located in the case along with the processor (in the chip). The level two cache is an intermediary between the processor, with its internal cache, and the RAM. It can be accessed more rapidly than the RAM, but less rapidly than the level one cache.
• Level three cache memory (called L3 Cache, for Level 3 Cache) is located on the motherboard.

All these levels of cache reduce the latency time of various memory types when processing or transferring information. While the processor works, the level one cache controller can interface with the level two controller to transfer information without impeding the processor. As well, the level two cache interfaces with the RAM (level three cache) to allow transfers without impeding normal processor operation.

Control Signals

Control signals are electronic signals that orchestrate the various processor units participating in the execution of an instruction. Control signals are sent using an element called a sequencer. For example, the Read / Write signal allows the memory to be told that the processor wants to read or write information.

Functional Units

The processor is made up of a group of interrelated units (or control units). Microprocessor architecture varies considerably from one design to another, but the main elements of a microprocessor are as follows:

• A control unit that links the incoming data, decodes it, and sends it to the execution unit:The control unit is made up of the following elements:
  • sequencer (or monitor and logic unit) that synchronizes instruction execution with the clock speed. It also sends control signals;
  • ordinal counter that contains the address of the instruction currently being executed;
  • instruction register that contains the following instruction.
• An execution unit (or processing unit) that accomplishes tasks assigned to it by the instruction unit. The execution unit is made of the following elements:
  • The arithmetical and logic unit (written ALU). The ALU performs basic arithmetical calculations and logic functions (AND, OR, EXCLUSIVE OR, etc.);
  • The floating point unit (written FPU) that performs partial complex calculations which cannot be done by the arithmetical and logic unit.
  • The status register;
  • The accumulator register.
• A bus management unit (or input-output unit) that manages the flow of incoming and outgoing information and that interfaces with system RAM;

The diagram below gives a simplified representation of the elements that make up the processor (the physical layout of the elements is different than their actual layout): 

Transistor

To process information, the microprocessor has a group of instructions, called the "instruction set", made possible by electronic circuits. More precisely, the instruction set is made with the help of semiconductors, little "circuit switches" that use the transistor effect, discovered in 1947 by John Barden, Walter H. Brattain and William Shockley who received a Nobel Prize in 1956 for it. 

A transistor (the contraction of transfer resistor) is an electronic semi-conductor component that has three electrodes and is capable of modifying current passing through it using one of its electrodes (called control electrode). These are referred to as "active components", in contrast to "passive components", such as resistance or capacitors which only have two electrodes (referred to as being "bipolar"). 

A MOS (metal, oxide, silicone) transistor is the most common type of transistor used to design integrated circuits. MOS transistors have two negatively charged areas, respectively called source (which has an almost zero charge) and drain (which has a 5V charge), separated by a positively charged region, called a substrate). The substrate has a control electrode overlaid, called a gate, that allows a charge to be applied to the substrate. 

When there is no charge on the control electrode, the positively charged substrate acts as a barrier and prevents electron movement from the source to the drain. However, when a charge is applied to the gate, the positive charges of the substrate are repelled and a negatively charged communication channel is opened between the source and the drain. 

The transistor therefore acts as a programmable switch, thanks to the control electrode. When a charge is applied to the control electrode, it acts as a closed interrupter and, when there is no charge, it acts as an open interrupter.

Integrated Circuits

Once combined, transistors can make logic circuits, that, when combined, form processors. The first integrated circuit dates back to 1958 and was built by Texas Instruments. 

MOS transistors are therefore made of slices of silicone (called wafers) obtained after multiple processes. These slices of silicone are cut into rectangular elements to form a "circuit". Circuits are then placed in cases with input-output connectors and the sum of these parts makes an "integrated circuit". The minuteness of the engraving, written in microns (micrometers, written Âµm) defines the number of transistors per surface unit. There can be millions of transistors on one single processor. 

Moore's Law, penned in 1965 by Gordon E. Moore, cofounder of Intel, predicted that processor performance (by extension of the number of transistors integrated in the silicone) would double every twelve months. This law was revised in 1975, bringing the number of months to 18. Moore’s Law is still being proven today. 

Because the rectangular case contains input-output pins that resemble legs, the term "electronic flea" is used in French to refer to integrated circuits.