Speed up Internet Explorer 6

Internet Explorer 6 has been around for a while and its been a good browser. Since new alternatives like Firefox and Opera have come out we now know that, yes there is faster browsing out there. Internet Explorer can be as fast after trying out a few tips in this article.

Step 1: Default is your friend.

You heard it here first folks. (probably not) Generally setting the browser to its defaults will make it go faster. There are two areas in specific that will make the largest impact. Security settings and the advanced settings. To set these at their defaults go to Internet Explorer. In the browser go to the tools menu and select internet options. In the internet options go to the security tab. In the security tab set all of the zones to default. Then go to the advanced tab. In the advanced tab you will find the restore defaults button at the bottom of the window. Click o it and that's it. Click on OK and restart your browser.

Step 2: Setting the Number of Connections per Session.

Internet explorer limits the number of connections it opens when you click on a link to open an new web page. Microsoft did this to comply with HTTP 1.1 standards but it also really slows down things when you open a new website and download the sites images. So to change that go to the start menu and select run. In the run command type regedit and click OK to open the registry editor. In the registry editor navigate to HKEY_CURRENT_USER SoftwareMicrosoftWindowsCurrentVersionInternet Settings. Here change the MaxConnectionsPerServer and MaxConnectionsPer1_0Server to a number you wish. That's it, once done restart windows and you are all set. Just a note that this will effect all windows applications that use the internet explorer api so if something else is not working right that is why.

Step 3: Keep less and save time.

Windows by default will automatically set your temporary internet files to a certain percentage of your hard drive. If you have a hard drive that is a 200 gigabytes your temporary internet files will be a couple of gigabytes in size. The more files that Internet Explorer has to look through the more time it takes to load a page. To change the size of your temporary internet files goto the tools menu in Internet Explorer and select internet options. In the internet options click on the settings buttons in the temporary internet files. Change the size to the desired amount (I usually use 100MB) and click on OK. Your computer might stall for a little bit if there are a lot of files to delete.

Its as easy as that. Three steps to speed up your internet browsing in Internet Explorer. I'm sure there is a whole lot more out there but these are the ones that will help you out the most. Till next time.

http://www.HowdidYa.com is an always growing how to portal for Windows, Linux, Mac OS and Hardware. Our how to articles will show you fix any problem, or modify your electronic stuff to make it your own. Visit our website to submit your own how to's or learn for others.

10 ways to get links to your site

Author: Robert Thomson

Find out how to get links to your site easy and how to increase your site ranking in SERP's. Here are 10 simple yet effective ways of raising your link popularity.
Getting links to your site increases traffic and boosts your rankings in the search engines queries.

Here are the 10 methods I used for getting links to one of my directories:

1. Directory submission
If you don't have time to do it your self, you should hire some one to do this for you, as this is the best and the safest way to increase your back links.

2. Link Exchange With Other Webmasters

This is a slow process and not always reciprocal linking is a good idea, cause search engines place more importance on one-way links than two-way links. Still, it can bring you valorous links, if you have what to exchange with.

3. Build A Network Of Websites And Interlink Them

Building multiple websites is always a good idea, but be careful to host them on different ips, not on the same server, as the search engines will believe you are manipulating their results and will most penalize your sites.

4. Write articles like this one. You can see in the footer my bio-box, that has 3 links. as you see, I am not writing the article for nothing.

5. Build a reciprocal directory
If you build a niche directory related to your site, many people with similar sites to yours will want to submit a link to it, and, in return, you could ask for a link to your site.

6. Build a theme / template for used scripts

Like Wordpress, or phpld. Put in the footer of the theme, your link, as in "Designed by yourlink.com". If you can't do one, you could always buy it from people that can. The catch here is to advertise it well.

7. Post on forums that allow you tho have a signature

You won’t get a great deal of of page rank, as most forums do not have a high page rank for their threads, but you will build up a good number of links, and as forums are generally very crowed by search engines, bots will follow the links to your site and and crawl your site on a regular basis.

8. Leave Comments On Blogs And Guest books

Don’t abuse it and start spamming other people’s blogs or guest books. Make comments to the subject, and make it look like you actually have something to contribute.

9. Write Good Testimonials

By writing and submitting testimonials to websites that you have previously purchased products or services from, you can get high-quality links to your site.

10. Buy Links

This can have a dramatic effect on your page rank and subsequently your search engine rankings if you can get links from PR6+ sites, however the only problem with this is that most links for sale are often for a set period of time, usually a month, and so you have to keep buying them to maintain your higher page rank and rankings.

About Author

Dugu is the owner of a free web directory, offers SEO services to hundreds of companies and designs wordpress themes in his free time.

Spyware - Get your Basics Right!

Author: Apurva

Spyware! Spyware! Nowadays, we all get to hear this word more often that what would make us feel comfortable. What exactly is Spyware? Spyware can be defined as any technology that aids a group in collecting information about a person or organization from their computers without their knowledge.
Spyware! Spyware! Nowadays, we all get to hear this word more often that what would make us feel comfortable. What exactly is Spyware? Spyware can be defined as any technology that aids a group in collecting information about a person or organization from their computers without their knowledge. This is widely accepted as an encroachment of privacy. Now, how does this spyware actually reach your computer? Spyware can be installed in your computer via any program or software your download in your machine, while surfing the net. In most cases, you will not realize that you have installed something unwanted till things start going wrong or rather start smelling fishy (not literally, though!). What you need here is a spyware removal program to bail you out.

Get Rid Of Spyware Programs

Ok, if it is unwanted and I want to get rid of spyware, I can delete it anytime with the help of the ‘add or remove programs’ feature in my computer! Why would I need a spyware removal program? Well, what you need to understand is that spyware are not just any Tom Dick and Harry looking through your stuff. Spyware mingle with your registry files. Looking for them and deleting the right files, is like looking for a needle in a haystack!

There are people who can inflict quite a big dent on your reputation with the help of spyware, if they are in the mood to do so! Damage? Yes, spyware programs are not necessarily innocent knowledge gathering gimmicks by advertising companies. Those are called adware programs. Spyware programs, also known as tracking software can actually turn your computer to a source of viruses for thousands of machines. If an investigation is carried out, you will be the one to face the rut!

Now that you have realized that spyware can be bad for your health, what can you do to ensure that it stays out of your life and the computer? The first step you can take is block pop ups in your browser. Second, try avoiding downloads from websites you are not sure of, especially downloading pirated versions of paid software. You may actually be downloading malicious spyware or irritating adware in your machine instead! Finally, do not click on any URLs sent you via emails, unless of course you are sure about its authenticity.

Look around for free spyware killer programs on the net. Companies like Microsoft, Google and Yahoo offer free spyware removal programs that can be updated regularly. Various companies are offering spyware removal tools for free or for a nominal charge. It would be a good idea to download a trial version of any of the programs free and then depending on your experience purchase the full version. Getting a full version is essential because the trial versions in most cases lack some key feature and do not offer full functionality.

About Author

spyware removal program

CD And DVD Duplication: An Untreated Threat

Author: Alex Crane

We often require CD and DVD duplication to avoid ourselves for losing our important data. However, it is the most time taking and confusing process. To avoid us from such hassles, CD and DVD duplicators are playing a great role.
We are still used to the process of CD or DVD duplicating which a time is taking process and if we need more CDs or DVDs to burn, then it’s a nightmare. This problem can be solved by the best use of the processes of CD/DVD duplicators that are available in the market. This is a growing market with the increase of services. Especially for our small companies if there is a need to make copies of any software or any material to send to our clients, or to distribute to our employees then the valuable resources of time and human resource are wasted.

The CDs/DVDs duplication machines save a lot of time by duplicating more number of CDs and DVDs with automatic machines that use robotic arms, which reduces the manual process.

CD/DVD duplication is a method of generating CDs and CD-ROMs by writing empty CD-R discs in a CD-R drive on a PC or by using a CD duplicator. We can also define the CDs/DVDs duplication as, the replica of the optical media through a process of copying. In general we refer it as creating discs to limited extent, which is a contradictory concept to the large-scale process of replication. The content that is required to copy is usually, duplicated to existing record able CDs or DVDs media.

CD Duplication is typical process, where the lesser amount of CDs and DVDs are manufactured at present. The information contained in the CD-R or DVD-R is thus, loaded into the burners. And, your all information is extracted from the source in digital form, generally the CD-R, CD-RW, DVD+R, and DVD+RW will transfer in to the empty discs. The information that is transferred is thus typically verified moreover the disc will then accepted / rejected.

Also, with the increase of advance technology and reasonable price in information technology, many companies are offering similar level of CDs and DVDs duplication services.

The process of CD/DVD duplication is done in two methods. One process is a manual process and another one is automatic. The manual process is used for those who require less CDs or DVDs to duplicate. The automatic process is used by those who need more number of CD/DVD duplicates to be done in a much faster way.

No wonder, with the DVD duplicators we can make the second copy of CDs within 3 to 4 minutes. The automatic CD/DVD duplicators use robotic arms to transfer blank discs from one spindle to another, which facilitates the work instead of manual transferring. By using suction picker or mechanical picker the CDs or DVDs are transferred from one spindle to another. This is a better method of duplicating CDs and DVDs in bulk.

There are many companies that offer cheap services of CD/DVD duplicating process. Most of the services are available on the Internet and the orders can be given online. We can compare the products, their features and the prices to choose the best CD/DVD duplicating machines. Depending on the use and requirements the best machine should be selected or can hire the services if it is not needed.

About Author

DISCWORKS are UK leaders for CD duplication. 24 hours turnaround available, CD replication from just 12p per disk unifying quality with price. Please visit http://www.samplez.co.uk/

Safe Computing 101 - Basic Computer Safety and Maintenance by Steve Burgess

Safe Computing 101 - Basic Computer Safety and Maintenance By Steve Burgess

The enemies of disk drives are dust, heat, impacts, liquid, voltage spikes, and Windows (I'm at least half kidding about Windows). Let's address them one at a time and what to do about them.

Liquid. Don't use your computer in the bathtub. Don't use your computer around happy hour. Don't spill your double mocha soy latte on your keyboard. I have dealt with recovering data resulting from spills around the latter two conditions. Yes, all the data came off, but martinis, coffee, and most other liquids simply don't mix with electronic components. It's useful to get a keyboard protector "skin" if you must imbibe and compute simultaneously.

Should you spill onto your keyboard or laptop without such a covering in the way, immediately flip over the keyboard (or laptop) onto a towel, unplug it, and let it dry out overnight or for a day or two. This works enough of the time that it's worth the wait. I have not personally had much luck with taking them apart and cleaning them out if this doesn't work.

Impacts. Don't drop your computer! Don't drop your disk drive. Have a padded bag for your laptop, but still treat it with care. Tossing and dropping a laptop, even in a padded bag, is bad for its health. Think how you would feel, tossed around in a bag! Many bags do not have enough padding on the bottom, so I have a hand towel in the bottom my laptop bag for extra padding. It's a good idea to position a desktop computer away from doors, away from inkjet printers, away from feet and pets, and away from drawers that might bang into the computer.

Voltage spikes. There are power fluctuations all day long in almost everybody's wiring. A surge protector power strip will help, but for full protection, one should really use an uninterruptible power supply (UPS). They're currently available for less than $50. There are models that will actually shut down your system "gracefully" - shut it down as if you were doing it, rather than just cutting off the power - in the event of a total power outage. Your data is worth the cost.

Another kind of voltage spike is a static discharge. This is what you get when you shuffle around on the carpet, then kiss your significant other, or zap your little brother in the cheek with your finger. It's actually high voltage and can damage your computer, especially if you have opened up the box & touched something inside. You can discharge yourself (after you have stopped shuffling on the carpet!) by touching grounded metal before touching your computer.

Heat Heat is public enemy number one for computers. Heat kills computers and disk drives. Disk drives generate heat and many people stack several disk drives together in their computer with no space between. Don't do it! Or at least add a hard drive cooling fan, which can be had for less than $5 at places like geeks.com. If possible, keep your computer out of sunny windows, and in a room (or car) at a reasonable temperature. If it's uncomfortably warm for you, it may also be so for your computer.

Dust Heat and dust walk hand in hand to damage your computer. Dust makes a fine blanket that accumulates over time to heat up you disk drive, your processor, plug up your fan, and - as an added bonus - it's conductive and can short out components in your computer. What to do?

Change the computer's location. A computer on the floor - especially on a rug under your desk - is a prime candidate for getting an internal blanket of dust. Place the computer off the floor - preferably a foot or more off the floor - and on a hard surface. Many of us have a desk that has a perfect little enclosed spot just made for a computer. It is also a perfect breeding ground for dust bunnies.

Dust out your computer every three months or so. If you've never done it, you will be shocked at how much dust comes out of it. You'll want to use clean compressed air - canned air works great, but if using an air compressor, make sure the air coming out is clean and dry by blowing it at a piece of white notebook paper first. Dirty or wet - don't use it. If using canned air, don't shake the can while spraying, or you will spray out ice-cold propellant that give components a thermal shock and wastes your canned air as well.

You'll want to have the computer unplugged. If possible, you'll want to have the computer's case open (unless it is a laptop). Blow out the system fan and any other fans that you see. Be careful not to dislodge the fan on the processor chip on the mother board. Blow out the space between the hard drives. Blow from the back of CD or DVD drives, and from the front of any floppy drives. Blow out any ports like USB ports or memory card slots. Blow out any other vents or slots. Keep going until no more dust comes out.

So, to review: heat bad, dust bad, dropping bad, liquid bad, voltage spikes bad, Windows - it's up to you.

To remedy: keep your computer comfortably cool; dust it out from time to time; locate it in an area free from bumping doors, feet, printers or pets; use a UPS; and for goodness sake, when you drink, practice safe...computing.

Steve Burgess is a freelance technology writer, a practicing computer forensics specialist as the principal of Burgess Forensics, and a contributor to the just-released Scientific Evidence in Civil and Criminal Cases, 5th Edition by Moenssens, et al. Mr. Burgess may be reached at http://www.datarecoveryworldwide.com or via email at info@datarecoveryworldwide.com
About the Author

Steve Burgess is a freelance technology writer, a practicing computer forensics specialist as the principal of Burgess Forensics, and a contributor to the just-released Scientific Evidence in Civil and Criminal Cases, 5th Edition by Moenssens, et al. Mr. Burgess may be reached at http://www.datarecoveryworldwide.com or via email at info@datarecoveryworldwide.com

How To Protect Your Computer From Viruses by J Camerlin

Unfortunately for us, there are many people out there who get a rise out of writing small programs that find ways onto our computers and in most cases destroy personal file, data or steal out identity. This article explains some steps we can take to defend ourselves.

What is a computer virus?

A computer virus is a small program that piggybacks on legitimate programs. It is called a virus because it shares the traits of a biological virus where is passes from one computer to another in the same manner a biological virus passes from one person to another person. Once a computer virus is running, it can infect other programs and documents.

Types of computer viruses:

There are many types of viruses but the most common are:

- Viruses: a small software program that attaches itself to other programs and/or documents
- E-mail viruses: these viruses move around through email and usually replicates itself by automatically mailing itself to people in the victim's address book
- Trojan horses: this is a computer program that claims to do one thing but instead does another such as erase your hard drive Worms: this is a program that finds a small hole in computer network security and replicates itself on to other computers on that network

How does a virus get into our computer and how do they spread?

Some of the most common ways a virus can get on your computer are:

- Downloading a program from an unknown source and running it
- Opening a file attachment from an e-mail
- Sharing infected files from one computer to another on a floppy disk
- Opening an electronic greeting card, audio and video files

What are the signs of a virus, am I infected?

- Your computer runs slower than normal
- The computer stops or locks up
- Your computer crashes and restart every few minutes
- The computer restarts on its own and does not run properly
- Applications on your computer do not run properly
- Hard drives or disk are not accessible
- Your computer cannot print properly
- Unusual error messages appear
- Menus and dialog boxes are distorted

What kinds of damage can a virus do?

The damage a computer virus can do depends on the type of virus it is. Here are some common threats.

- They can delete or change files. Some viruses will delete all your files or even reformat your hard drive making your computer unusable
- Other viruses will steal personal information like credit card numbers, account numbers and passwords
- Some viruses will slow down your computer dramatically
- Some viruses change security settings allowing hackers to gain access to your computer and steal information
- Other viruses like worms infect computers on a network

What you can do to protect your computer from viruses?

There are number of ways to protect your computer from a virus: - Do not open any attachments your received in an e-mail even if you know the person who sent it. That person may not be aware they are sending an infected files
- If you receive an e-mail with an attachment from some one your do not know, DELETE the e-mail right away
- Before you copy a file to your computer, scan it with an anti-virus program
- If you download a file from the Internet, copy it to your hard drive first, scan it with an anti-virus program before to open the file or run it
- if some sends you a greeting card or a joke that you have to launch to view, be awry and stay on the safe side and do not open it
- The best defense against computer viruses and to use an anti-virus program that will scan your e-mail, act as a firewall, hard drive and keep up-to-date with the latest viruses. It is reported that there are over 500 new viruses discovered each month

Fortunately for us, there are a number of software programs available to prevent, detect and kill computer viruses. I recommend the one below, I use it and it is one of the most popular anti-virus programs around.

Computer Is Developping And Becomes a Part Of Our Lives

Computer
From Wikipedia, the free encyclopedia
Jump to: navigation, search
For the IEEE magazine see Computer (magazine).

The NASA Columbia Supercomputer.
A computer is a machine for manipulating data according to a list of instructions.
Computers take numerous physical forms. Early electronic computers were the size of a large room, consuming as much power as several hundred modern personal computers. [1] Today, computers can be made small enough to fit into a wrist watch and be powered from a watch battery. Society has come to recognize personal computers and their portable equivalent, the laptop computer, as icons of the information age; they are what most people think of as "a computer". However, the most common form of computer in use today is by far the embedded computer. Embedded computers are small, simple devices that are often used to control other devices—for example, they may be found in machines ranging from fighter aircraft to industrial robots, digital cameras, and even children's toys.

A computer in a wristwatch.
The ability to store and execute programs makes computers extremely versatile and distinguishes them from calculators. The Church–Turing thesis is a mathematical statement of this versatility: Any computer with a certain minimum capability is, in principle, capable of performing the same tasks that any other computer can perform. Therefore, computers with capability and complexity ranging from that of a personal digital assistant to a supercomputer are all able to perform the same computational tasks as long as time and storage capacity are not considerations.
Contents
1 History of computing
2 Stored program architecture
2.1 Programs
2.2 Example
3 How computers work
3.1 Control unit
3.2 Arithmetic/logic unit (ALU)
3.3 Memory
3.4 Input/output (I/O)
3.5 Multitasking
3.6 Multiprocessing
3.7 Networking and the Internet
4 Further topics
4.1 Hardware
4.2 Software
4.3 Programming languages
4.4 Professions and organizations
5 See also
6 Notes
7 References
//

History of computing
Main article: History of computing

The Jacquard loom was one of the first programmable devices.
It is difficult to define any one device as the earliest computer. The very definition of a computer has changed and it is therefore impossible to identify the first computer. Many devices once called "computers" would no longer qualify as such by today's standards.
Originally, the term "computer" referred to a person who performed numerical calculations (a human computer), often with the aid of a mechanical calculating device. Examples of early mechanical computing devices included the abacus, the slide rule and arguably the astrolabe and the Antikythera mechanism (which dates from about 150-100 BC). The end of the Middle Ages saw a re-invigoration of European mathematics and engineering, and Wilhelm Schickard's 1623 device was the first of a number of mechanical calculators constructed by European engineers.
However, none of those devices fit the modern definition of a computer because they could not be programmed. In 1801, Joseph Marie Jacquard made an improvement to the textile loom that used a series of punched paper cards as a template to allow his loom to weave intricate patterns automatically. The resulting Jacquard loom was an important step in the development of computers because the use of punched cards to define woven patterns can be viewed as an early, albeit limited, form of programmability.
In 1837, Charles Babbage was the first to conceptualize and design a fully programmable mechanical computer that he called "The Analytical Engine".[2] Due to limited finance, and an inability to resist tinkering with the design, Babbage never actually built his Analytical Engine.
Large-scale automated data processing of punched cards was performed for the US Census in 1890 by tabulating machines designed by Herman Hollerith and manufactured by the Computing Tabulating Recording Corporation, which later became IBM. By the end of the 19th century a number of technologies that would later prove useful in the realization of practical computers had begun to appear: the punched card, boolean algebra, the vacuum tube (thermionic valve) and the teleprinter.
During the first half of the 20th century, many scientific computing needs were met by increasingly sophisticated analog computers, which used a direct mechanical or electrical model of the problem as a basis for computation. However, these were not programmable and generally lacked the versatility and accuracy of modern digital computers.
Defining characteristics of five first operative digital computers
Computer
Shown working
Binary
Electronic
Programmable
Turing complete
Zuse Z3
May 1941
Yes
No
By punched film stock
Yes (1998)
Atanasoff-Berry Computer
Summer 1941
Yes
Yes
No
No
Colossus
December 1943 / January 1944
Yes
Yes
Partially, by rewiring
No
Harvard Mark I - IBM ASCC
1944
No
No
By punched paper tape
No
ENIAC
1944
No
Yes
Partially, by rewiring
Yes
1948
No
Yes
By Function Table ROM
Yes
A succession of steadily more powerful and flexible computing devices were constructed in the 1930s and 1940s, gradually adding the key features that are seen in modern computers. The use of digital electronics (largely invented by Claude Shannon in 1937) and more flexible programmability were vitally important steps, but defining one point along this road as "the first digital electronic computer" is difficult (Shannon 1940). Notable achievements include:

EDSAC was one of the first computers to implement the stored program (von Neumann) architecture.
Konrad Zuse's electromechanical "Z machines". The Z3 (1941) was the first working machine featuring binary arithmetic, including floating point arithmetic and a measure of programmability. In 1998 the Z3 was proved to be Turing complete, therefore being the world's first operational computer.
The Atanasoff-Berry Computer (1941) which used vacuum tube based computation, binary numbers, and regenerative capacitor memory.
The secret British Colossus computer (1944), which had limited programmability but demonstrated that a device using thousands of tubes could be reasonably reliable and electronically reprogrammable. It was used for breaking German wartime codes.
The Harvard Mark I (1944), a large-scale electromechanical computer with limited programmability.
The US Army's Ballistics Research Laboratory ENIAC (1946), which used decimal arithmetic and was the first general purpose electronic computer, although it initially had an inflexible architecture which essentially required rewiring to change its programming.
Several developers of ENIAC, recognizing its flaws, came up with a far more flexible and elegant design, which came to be known as the stored program architecture or von Neumann architecture. This design was first formally described by John von Neumann in the paper "First Draft of a Report on the EDVAC", published in 1945. A number of projects to develop computers based on the stored program architecture commenced around this time, the first of these being completed in Great Britain. The first to be demonstrated working was the Manchester Small-Scale Experimental Machine (SSEM) or "Baby". However, the EDSAC, completed a year after SSEM, was perhaps the first practical implementation of the stored program design. Shortly thereafter, the machine originally described by von Neumann's paper—EDVAC—was completed but didn't see full-time use for an additional two years.
Nearly all modern computers implement some form of the stored program architecture, making it the single trait by which the word "computer" is now defined. By this standard, many earlier devices would no longer be called computers by today's definition, but are usually referred to as such in their historical context. While the technologies used in computers have changed dramatically since the first electronic, general-purpose computers of the 1940s, most still use the von Neumann architecture. The design made the universal computer a practical reality.

Microprocessors are miniaturized devices that often implement stored program CPUs.
Vacuum tube-based computers were in use throughout the 1950s, but were largely replaced in the 1960s by transistor-based devices, which were smaller, faster, cheaper, used less power and were more reliable. These factors allowed computers to be produced on an unprecedented commercial scale. By the 1970s, the adoption of integrated circuit technology and the subsequent creation of microprocessors such as the Intel 4004 caused another leap in size, speed, cost and reliability. By the 1980s, computers had become sufficiently small and cheap to replace simple mechanical controls in domestic appliances such as washing machines. Around the same time, computers became widely accessible for personal use by individuals in the form of home computers and the now ubiquitous personal computer. In conjunction with the widespread growth of the Internet since the 1990s, personal computers are becoming as common as the television and the telephone and almost all modern electronic devices contain a computer of some kind.

Stored program architecture
Main articles: Computer program and Computer programming
The defining feature of modern computers which distinguishes them from all other machines is that they can be programmed. That is to say that a list of instructions (the program) can be given to the computer and it will store them and carry them out at some time in the future.
In most cases, computer instructions are simple: add one number to another, move some data from one location to another, send a message to some external device, etc. These instructions are read from the computer's memory and are generally carried out (executed) in the order they were given. However, there are usually specialized instructions to tell the computer to jump ahead or backwards to some other place in the program and to carry on executing from there. These are called "jump" instructions (or branches). Furthermore, jump instructions may be made to happen conditionally so that different sequences of instructions may be used depending on the result of some previous calculation or some external event. Many computers directly support subroutines by providing a type of jump that "remembers" the location it jumped from and another instruction to return to that point.
Program execution might be likened to reading a book. While a person will normally read each word and line in sequence, they may at times jump back to an earlier place in the text or skip sections that are not of interest. Similarly, a computer may sometimes go back and repeat the instructions in some section of the program over and over again until some internal condition is met. This is called the flow of control within the program and it is what allows the computer to perform tasks repeatedly without human intervention.
Comparatively, a person using a pocket calculator can perform a basic arithmetic operation such as adding two numbers with just a few button presses. But to add together all of the numbers from 1 to 1,000 would take thousands of button presses and a lot of time—with a near certainty of making a mistake. On the other hand, a computer may be programmed to do this with just a few simple instructions. For example: mov #0,sum ; set sum to 0
mov #1,num ; set num to 1
loop: add num,sum ; add num to sum
add #1,num ; add 1 to num
cmp num,#1000 ; compare num to 1000
ble loop ; if num <= 1000, go back to 'loop'
halt ; end of program. stop running
Once told to run this program, the computer will perform the repetitive addition task without further human intervention. It will almost never make a mistake and a modern PC can complete the task in about a millionth of a second.[3]
However, computers cannot "think" for themselves in the sense that they only solve problems in exactly the way they are programmed to. An intelligent human faced with the above addition task might soon realize that instead of actually adding up all the numbers one can simply use the equation

and arrive at the correct answer (500,500) with little work. [4] In other words, a computer programmed to add up the numbers one by one as in the example above would do exactly that without regard to efficiency or alternative solutions.

Programs

A 1970s punched card containing one line from a FORTRAN program. The card reads: "Z(1) = Y + W(1)" and is labelled "PROJ039" for identification purposes.
In practical terms, a computer program might include anywhere from a dozen instructions to many millions of instructions for something like a word processor or a web browser. A typical modern computer can execute billions of instructions every second and nearly never make a mistake over years of operation.
Large computer programs may take teams of computer programmers years to write and the probability of the entire program having been written completely in the manner intended is unlikely. Errors in computer programs are called bugs. Sometimes bugs are benign and do not affect the usefulness of the program, in other cases they might cause the program to completely fail (crash), in yet other cases there may be subtle problems. Sometimes otherwise benign bugs may be used for malicious intent, creating a security exploit. Bugs are usually not the fault of the computer. Since computers merely execute the instructions they are given, bugs are nearly always the result of programmer error or an oversight made in the program's design. [5]
In most computers, individual instructions are stored as machine code with each instruction being given a unique number (its operation code or opcode for short). The command to add two numbers together would have one opcode, the command to multiply them would have a different opcode and so on. The simplest computers are able to perform any of a handful of different instructions, the more complex computers have several hundred to choose from—each with a unique numerical code. Since the computer's memory is able to store numbers, it can also store the instruction codes. This leads to the important fact that entire programs (which are just lists of instructions) can be represented as lists of numbers and can themselves be manipulated inside the computer just as if they were numeric data. The fundamental concept of storing programs in the computer's memory alongside the data they operate on is the crux of the von Neumann, or stored program, architecture. In some cases, a computer might store some or all of its program in memory that is kept separate from the data it operates on. This is called the Harvard architecture after the Harvard Mark I computer. Modern von Neumann computers display some traits of the Harvard architecture in their designs, such as in CPU caches.
While it is possible to write computer programs as long lists of numbers (machine language) and this technique was used with many early computers,[6] it is extremely tedious to do so in practice, especially for complicated programs. Instead, each basic instruction can be given a short name that is indicative of its function and easy to remember—a mnemonic such as ADD, SUB, MULT or JUMP. These mnemonics are collectively known as a computer's assembly language. Converting programs written in assembly language into something the computer can actually understand (machine language) is usually done by a computer program called an assembler. Machine languages and the assembly languages that represent them (collectively termed low-level programming languages) tend to be unique to a particular type of computer. This means that an ARM architecture computer (such as may be found in a PDA or a hand-held videogame) cannot understand the machine language of an Intel Pentium or the AMD Athlon 64 computer that might be in a PC.[7]
Though considerably easier than in machine language, writing long programs in assembly language is often difficult and error prone. Therefore, most complicated programs are written in more abstract high-level programming languages that are able to express the needs of the computer programmer more conveniently (and thereby help reduce programmer error). High level languages are usually "compiled" into machine language (or sometimes into assembly language and then into machine language) using another computer program called a compiler.[8] Since high level languages are more abstract than assembly language, it is possible to use different compilers to translate the same high level language program into the machine language of many different types of computer. This is part of the means by which software like video games may be made available for different computer architectures such as personal computers and various video game consoles.
The task of developing large software systems is an immense intellectual effort. It has proven, historically, to be very difficult to produce software with an acceptably high reliability, on a predictable schedule and budget. The academic and professional discipline of software engineering concentrates specifically on this problem.

Example

A traffic light showing red.
Suppose a computer is being employed to drive a traffic light. A simple stored program might say:
Turn off all of the lights
Turn on the red light
Wait for sixty seconds
Turn off the red light
Turn on the green light
Wait for sixty seconds
Turn off the green light
Turn on the yellow light
Wait for two seconds
Turn off the yellow light
Jump to instruction number (2)
With this set of instructions, the computer would cycle the light continually through red, green, yellow and back to red again until told to stop running the program.
However, suppose there is a simple on/off switch connected to the computer that is intended be used to make the light flash red while some maintenance operation is being performed. The program might then instruct the computer to:
Turn off all of the lights
Turn on the red light
Wait for sixty seconds
Turn off the red light
Turn on the green light
Wait for sixty seconds
Turn off the green light
Turn on the yellow light
Wait for two seconds
Turn off the yellow light
If the maintenance switch is NOT turned on then jump to instruction number 2
Turn on the red light
Wait for one second
Turn off the red light
Wait for one second
Jump to instruction number 11
In this manner, the computer is either running the instructions from number (2) to (11) over and over or it's running the instructions from (11) down to (16) over and over, depending on the position of the switch.[9]

How computers work
Main articles: Central processing unit and Microprocessor
A general purpose computer has four main sections: the arithmetic and logic unit (ALU), the control unit, the memory, and the input and output devices (collectively termed I/O). These parts are interconnected by busses, often made of groups of wires.
The control unit, ALU, registers, and basic I/O (and often other hardware closely linked with these) are collectively known as a central processing unit (CPU). Early CPUs were comprised of many separate components but since the mid-1970s CPUs have typically been constructed on a single integrated circuit called a microprocessor.

Control unit
Main articles: CPU design and Control unit
The control unit (often called a control system or central controller) directs the various components of a computer. It reads and interprets (decodes) instructions in the program one by one. The control system decodes each instruction and turns it into a series of control signals that operate the other parts of the computer.[10] Control systems in advanced computers may change the order of some instructions so as to improve performance.
A key component common to all CPUs is the program counter, a special memory cell (a register) that keeps track of which location in memory the next instruction is to be read from.[11]

Diagram showing how a particular MIPS architecture instruction would be decoded by the control system.
The control system's function is as follows—note that this is a simplified description and some of these steps may be performed concurrently or in a different order depending on the type of CPU:
Read the code for the next instruction from the cell indicated by the program counter.
Decode the numerical code for the instruction into a set of commands or signals for each of the other systems.
Increment the program counter so it points to the next instruction.
Read whatever data the instruction requires from cells in memory (or perhaps from an input device). The location of this required data is typically stored within the instruction code.
Provide the necessary data to an ALU or register.
If the instruction requires an ALU or specialized hardware to complete, instruct the hardware to perform the requested operation.
Write the result from the ALU back to a memory location or to a register or perhaps an output device.
Jump back to step (1).
Since the program counter is (conceptually) just another set of memory cells, it can be changed by calculations done in the ALU. Adding 100 to the program counter would cause the next instruction to be read from a place 100 locations further down the program. Instructions that modify the program counter are often known as "jumps" and allow for loops (instructions that are repeated by the computer) and often conditional instruction execution (both examples of control flow).
It is noticeable that the sequence of operations that the control unit goes through to process an instruction is in itself like a short computer program - and indeed, in some more complex CPU designs, there is another yet smaller computer called a microsequencer that runs a microcode program that causes all of these events to happen.

Arithmetic/logic unit (ALU)
Main article: Arithmetic logic unit
The ALU is capable of performing two classes of operations: arithmetic and logic.
The set of arithmetic operations that a particular ALU supports may be limited to adding and subtracting or might include multiplying or dividing, trigonometry functions (sine, cosine, etc) and square roots. Some can only operate on whole numbers (integers) whilst others use floating point to represent real numbers—albeit with limited precision. However, any computer that is capable of performing just the simplest operations can be programmed to break down the more complex operations into simple steps that it can perform. Therefore, any computer can be programmed to perform any arithmetic operation—although it will take more time to do so if its ALU does not directly support the operation. An ALU may also compare numbers and return boolean truth values (true or false) depending on whether one is equal to, greater than or less than the other ("is 64 greater than 65?").
Logic operations involve boolean logic: AND, OR, XOR and NOT. These can be useful both for creating complicated conditional statements and processing boolean logic.
Superscalar computers contain multiple ALUs so that they can process several instructions at the same time. Graphics processors and computers with SIMD and MIMD features often provide ALUs that can perform arithmetic on vectors and matrices.

Memory
Main article: Computer storage

Magnetic core memory was popular main memory for computers through the 1960s until it was completely replaced by semiconductor memory.
A computer's memory can be viewed as a list of cells into which numbers can be placed or read. Each cell has a numbered "address" and can store a single number. The computer can be instructed to "put the number 123 into the cell numbered 1357" or to "add the number that is in cell 1357 to the number that is in cell 2468 and put the answer into cell 1595". The information stored in memory may represent practically anything. Letters, numbers, even computer instructions can be placed into memory with equal ease. Since the CPU does not differentiate between different types of information, it is up to the software to give significance to what the memory sees as nothing but a series of numbers.
In almost all modern computers, each memory cell is set up to store binary numbers in groups of eight bits (called a byte). Each byte is able to represent 256 different numbers; either from 0 to 255 or -128 to +127. To store larger numbers, several consecutive bytes may be used (typically, two, four or eight). When negative numbers are required, they are usually stored in two's complement notation. Other arrangements are possible, but are usually not seen outside of specialized applications or historical contexts. A computer can store any kind of information in memory as long as it can be somehow represented in numerical form. Modern computers have billions or even trillions of bytes of memory.
The CPU contains a special set of memory cells called registers that can be read and written to much more rapidly than the main memory area. There are typically between two and one hundred registers depending on the type of CPU. Registers are used for the most frequently needed data items to avoid having to access main memory every time data is needed. Since data is constantly being worked on, reducing the need to access main memory (which is often slow compared to the ALU and control units) greatly increases the computer's speed.
Computer main memory comes in two principal varieties: random access memory or RAM and read-only memory or ROM. RAM can be read and written to anytime the CPU commands it, but ROM is pre-loaded with data and software that never changes, so the CPU can only read from it. ROM is typically used to store the computer's initial start-up instructions. In general, the contents of RAM is erased when the power to the computer is turned off while ROM retains its data indefinitely. In a PC, the ROM contains a specialized program called the BIOS that orchestrates loading the computer's operating system from the hard disk drive into RAM whenever the computer is turned on or reset. In embedded computers, which frequently do not have disk drives, all of the software required to perform the task may be stored in ROM. Software that is stored in ROM is often called firmware because it is notionally more like hardware than software. Flash memory blurs the distinction between ROM and RAM by retaining data when turned off but being rewritable like RAM. However, flash memory is typically much slower than conventional ROM and RAM so its use is restricted to applications where high speeds are not required. [12]
In more sophisticated computers there may be one or more RAM cache memories which are slower than registers but faster than main memory. Generally computers with this sort of cache are designed to move frequently needed data into the cache automatically, often without the need for any intervention on the programmer's part.

Input/output (I/O)
Main article: Input/output

Hard disks are common I/O devices used with computers.
I/O is the means by which a computer receives information from the outside world and sends results back. Devices that provide input or output to the computer are called peripherals. On a typical personal computer, peripherals include inputs like the keyboard and mouse, and outputs such as the display and printer. Hard disks, floppy disks and optical discs serve as both inputs and outputs. Computer networking is another form of I/O.
Practically any device that can be made to interface digitally may be used as I/O. The computer in the Engine Control Unit of a modern automobile might read the position of the pedals and steering wheel, the output of the oxygen sensor and devices that monitor the speed of each wheel. The output devices include the various lights and gauges that the driver sees as well as the engine controls such as the spark ignition circuits and fuel injection systems. In a digital wristwatch, the computer reads the buttons and causes numbers and symbols to be shown on the liquid crystal display.
Often, I/O devices are complex computers in their own right with their own CPU and memory. A graphics processing unit might contain fifty or more tiny computers that perform the calculations necessary to display 3D graphics. Modern desktop computers contain many smaller computers that assist the main CPU in performing I/O.

Multitasking
Main article: Computer multitasking
While a computer may be viewed as running one gigantic program stored in its main memory, in some systems it is necessary to give the appearance of running several programs simultaneously. This is achieved by having the computer switch rapidly between running each program in turn. One means by which this is done is with a special signal called an interrupt which can periodically cause the computer to stop executing instructions where it was and do something else instead. By remembering where it was executing prior to the interrupt, the computer can return to that task later. If several programs are running "at the same time", then the interrupt generator might be causing several hundred interrupts per second, causing a program switch each time. Since modern computers typically execute instructions several orders of magnitude faster than human perception, it may appear that many programs are running at the same time even though only one is ever executing in any given instant. This method of multitasking is sometimes termed "time-sharing" since each program is allocated a "slice" of time in turn.
Before the era of cheap computers, the principle use for multitasking was to allow many people to share the same computer.
Seemingly, multitasking would cause a computer that is switching between several programs to run more slowly - in direct proportion to the number of programs it is running. However, most programs spend much of their time waiting for slow input/output devices to complete their tasks. If a program is waiting for the user to click on the mouse or press a key on the keyboard, then it will not take a "time slice" until the event it is waiting for has occurred. This frees up time for other programs to execute so that many programs may be run at the same time without unacceptable speed loss.

Multiprocessing
Main article: Multiprocessing

Cray designed many supercomputers that used multiprocessing heavily.
Some computers may divide their work between one or more separate CPUs, creating a multiprocessing configuration. Traditionally, this technique was utilized only in large and powerful computers such as supercomputers, mainframe computers and servers. However, multiprocessor and multi-core (multiple CPUs on a single integrated circuit) personal and laptop computers have become widely available and are beginning to see increased usage in lower-end markets as a result.
Supercomputers in particular often have highly unique architectures that differ significantly from the basic stored-program architecture and from general purpose computers.[13] They often feature thousands of CPUs, customized high-speed interconnects, and specialized computing hardware. Such designs tend to be useful only for specialized tasks due to the large scale of program organization required to successfully utilize most of a the available resources at once. Supercomputers usually see usage in large-scale simulation, graphics rendering, and cryptography applications, as well as with other so-called "embarrassingly parallel" tasks.

Networking and the Internet
Main articles: Computer networking and Internet

Visualization of a portion of the routes on the Internet.
Computers have been used to coordinate information in multiple locations since the 1950s, with the US military's SAGE system the first large-scale example of such a system, which led to a number of special-purpose commercial systems like Sabre.
In the 1970s, computer engineers at research institutions throughout the US began to link their computers together using telecommunications technology. This effort was funded by ARPA (now DARPA), and the computer network that it produced was called the ARPANET. The technologies that made the Arpanet possible spread and evolved. In time, the network spread beyond academic and military institutions and became known as the Internet. The emergence of networking involved a redefinition of the nature and boundaries of the computer. Computer operating systems and applications were modified to include the ability to define and access the resources of other computers on the network, such as peripheral devices, stored information, and the like, as extensions of the resources of an individual computer. Initially these facilities were available primarily to people working in high-tech environments, but in the 1990s the spread of applications like e-mail and the World Wide Web, combined with the development of cheap, fast networking technologies like Ethernet and ADSL saw computer networking become almost ubiquitous. In fact, the number of computers that are networked is growing phenomenally. A very large proportion of personal computers regularly connect to the Internet to communicate and receive information. "Wireless" networking, often utilizing mobile phone networks, has meant networking is becoming increasingly ubiquitous even in mobile computing environments.

Further topics

Hardware
The term hardware covers all of those parts of a computer that are tangible objects. Circuits, displays, power supplies, cables, keyboards, printers and mice are all hardware.
History of computing hardware
First Generation (Mechanical/Electromechanical)
Calculators
Antikythera mechanism, Difference Engine, Norden bombsight
Programmable Devices
Jacquard loom, Analytical Engine, Harvard Mark I, Z3
Second Generation (Vacuum Tubes)
Calculators
Atanasoff-Berry Computer
Programmable Devices
ENIAC, EDSAC, EDVAC, UNIVAC I
Third Generation (Discrete transistors and SSI, MSI, LSI Integrated circuits)
Mainframes
System/360, BUNCH
Minicomputer
PDP-8, PDP-11, System/32, System/36
Fourth Generation (VLSI integrated circuits)
Minicomputer
VAX, AS/400
4-bit microcomputer
Intel 4004, Intel 4040
8-bit microcomputer
Intel 8008, Intel 8080, Motorola 6800, Motorola 6809, MOS Technology 6502, Zilog Z80
16-bit microcomputer
8088, Zilog Z8000, WDC 65816/65802
32-bit microcomputer
80386, Pentium, 68000, ARM architecture
64-bit microcomputer [14]
x86-64, PowerPC, MIPS, SPARC
Embedded computer
8048, 8051
Personal computer
Desktop computer, Home computer, Laptop computer, Personal digital assistant (PDA), Portable computer, Tablet computer, Wearable computer
Server class computer
Theoretical/experimental
Quantum computer
Chemical computer
DNA computing
Optical computer
Other Hardware Topics
Peripheral device (Input/output)
Input
Mouse, Keyboard, Joystick, Image scanner
Output
Monitor, Printer
Both
Floppy disk drive, Hard disk, Optical disc drive, Teleprinter
Computer busses
Short range
RS-232, SCSI, PCI, USB
Long range (Computer networking)
Ethernet, ATM, FDDI

Software
Software refers to parts of the computer that have no material form; programs, data, protocols, etc are all software. When software is stored in hardware that cannot easily be modified (such as BIOS ROM in an IBM PC compatible), it is sometimes termed firmware to indicate that it falls into an area of uncertainty between hardware and software.
Computer software
Operating system
Unix/BSD
UNIX System V, AIX, HP-UX, Solaris (SunOS), FreeBSD, NetBSD, IRIX
GNU/Linux
List of Linux distributions, Comparison of Linux distributions
Microsoft Windows
Windows 9x, Windows NT, Windows CE
DOS
QDOS, PC-DOS, MS-DOS, FreeDOS
Mac OS
Mac OS classic, Mac OS X
Embedded and real-time
List of embedded operating systems
Experimental
Amoeba, Oberon/Bluebottle, Plan 9 from Bell Labs
Library
Multimedia
DirectX, OpenGL, OpenAL
Programming library
C standard library, Standard template library
Data
Protocol
TCP/IP, Kermit, FTP, HTTP, SMTP
File format
HTML, XML, JPEG, MPEG, PNG
User interface
Graphical user interface (WIMP)
Microsoft Windows, GNOME, QNX Photon, CDE, GEM
Text user interface
Command line interface, shells
Other
Application
Office suite
Word processing, Desktop publishing, Presentation program, Database management system, Scheduling & Time management, Spreadsheet, Accounting software
Internet Access
Browser, E-mail client, Web server, Mail transfer agent, Instant messaging
Design and manufacturing
Computer-aided design, Computer-aided manufacturing, Plant management, Robotic manufacturing, Supply chain management
Graphics
Raster graphics editor, Vector graphics editor, 3D modeler, Animation editor, 3D computer graphics, Video editing, Image processing
Audio
Digital audio editor, Audio playback, Mixing, Audio synthesis, Computer music
Software Engineering
Compiler, Assembler, Interpreter, Debugger, Text Editor, Integrated development environment, Performance analysis, Revision control, Software configuration management
Educational
Edutainment, Educational game, Serious game, Flight simulator
Games
Strategy, Arcade, Puzzle, Simulation, First-person shooter, Platform, Massively multiplayer, Interactive fiction
Misc
Artificial intelligence, Antivirus software, Malware scanner, Installer/Package management systems, File manager

Programming languages
Programming languages provide various ways of specifying programs for computers to run. Unlike natural languages, programming languages are designed to permit no ambiguity and to be concise. They are purely written languages and are often difficult to read aloud. They are generally either translated into machine language by a compiler or an assembler before being run, or translated directly at run time by an interpreter. Sometimes programs are executed by a hybrid method of the two techniques. There are thousands of different programming languages—some intended to be general purpose, others useful only for highly specialized applications.
Programming Languages
Lists of programming languages
Timeline of programming languages, Categorical list of programming languages, Generational list of programming languages, Alphabetical list of programming languages, Non-English-based programming languages
Commonly used Assembly languages
ARM, MIPS, x86
Commonly used High level languages
BASIC, C, C++, C#, COBOL, Fortran, Java, Lisp, Pascal
Commonly used Scripting languages
JavaScript, Python, Ruby, PHP, Perl

Professions and organizations
As the use of computers has spread throughout society, there are an increasing number of careers involving computers. Following the theme of hardware, software and firmware, the brains of people who work in the industry are sometimes known irreverently as wetware or "meatware".
Computer-related professions
Hardware-related
Electrical engineering, Electronics engineering, Computer engineering, Telecommunications engineering, Optical engineering, Nanoscale engineering
Software-related
Human-computer interaction, Information technology, Software engineering, Scientific computing, Web design, Desktop publishing, Sound recording and reproduction
The need for computers to work well together and to be able to exchange information has spawned the need for many standards organizations, clubs and societies of both a formal and informal nature.
Organizations
Standards groups
ANSI, IEC, IEEE, IETF, ISO, W3C
Professional Societies
ACM, ACM Special Interest Groups, IET, IFIP
Free/Open source software groups
Free Software Foundation, Mozilla Foundation, Apache Software Foundation

See also

Look up Computer inWiktionary, the free dictionary.

Wikiquote has a collection of quotations related to:
Computers

Wikimedia Commons has media related to:
Computer
Computability theory
Computer science
Computing
Computers in fiction
Computer security and Computer insecurity
List of computer term etymologies
Virtualization

Notes
^ In 1946, ENIAC consumed an estimated 174 kW. By comparison, a typical personal computer may use around 400 W; over four hundred times less. (Kempf 1961)
^ The Analytical Engine should not be confused with Babbage's difference engine which was a non-programmable mechanical calculator.
^ This program was designed for the PDP-11 minicomputer and shows some typical things a computer can do. All the text after the semicolons are comments for the benefit of human readers. These have no significance to the computer and are ignored. (Digital Equipment Corporation 1972)
^ Attempts are often made to create programs that can overcome this fundamental limitation of computers. Software that mimics learning and adaptation is part of artificial intelligence.
^ It is not universally true that bugs are solely due to programmer oversight. Computer hardware may fail or may itself have a fundamental problem that produces unexpected results in certain situations. For instance, the Pentium FDIV bug caused some Intel microprocessors in the early 1990s to produce inaccurate results for certain floating point division operations. This was caused by a flaw in the microprocessor design and resulted in a partial recall of the affected devices.
^ Even some later computers were commonly programmed directly in machine code. Some minicomputers like the DEC PDP-8 could be programmed directly from a panel of switches. However, this method was usually used only as part of the booting process. Most modern computers boot entirely automatically by reading a boot program from some non-volatile memory.
^ However, there is sometimes some form of machine language compatibility between different computers. An x86-64 compatible microprocessor like the AMD Athlon 64 is able to run most of the same programs that an Intel Core 2 microprocessor can, as well as programs designed for earlier microprocessors like the Intel Pentiums and Intel 80486. This contrasts with very early commercial computers, which were often one-of-a-kind and totally incompatible with other computers.
^ High level languages are also often interpreted rather than compiled. Interpreted languages are translated into machine code on the fly by another program called an interpreter.
^ Although this is a simple program, it contains a software bug. If the traffic signal is showing red when someone switches the "flash red" switch, it will cycle through green once more before starting to flash red as instructed. This bug is quite easy to fix by changing the program to repeatedly test the switch throughout each "wait" period—but writing large programs that have no bugs is exceedingly difficult.
^ The control unit's rule in interpreting instructions has varied somewhat in the past. While the control unit is solely responsible for instruction interpretation in most modern computers, this is not always the case. Many computers include some instructions that may only be partially interpreted by the control system and partially interpreted by another device. This is especially the case with specialized computing hardware that may be partially self-contained. For example, EDVAC, the first modern stored program computer to be designed, used a central control unit that only interpreted four instructions. All of the arithmetic-related instructions were passed on to its arithmetic unit and further decoded there.
^ Instructions often occupy more than one memory address, so the program counters usually increases by the number of memory locations required to store one instruction.
^ Flash memory also may only be rewritten a limited number of times before wearing out, making it less useful for heavy random access usage. (Verma 1988)
^ However, it is also very common to construct supercomputers out of many pieces of cheap commodity hardware; usually individual computers connected by networks. These so-called computer clusters can often provide supercomputer performance at a much lower cost than customized designs. While custom architectures are still used for most of the most powerful supercomputers, there has been a proliferation of cluster computers in recent years. (TOP500 2006)
^ Most major 64-bit instruction set architectures are extensions of earlier designs. All of the architectures listed in this table existed in 32-bit forms before their 64-bit incarnations were introduced.

References
a Kempf, Karl (1961). "Historical Monograph: Electronic Computers Within the Ordnance Corps". Aberdeen Proving Ground (United States Army).
a Phillips, Tony (2000). The Antikythera Mechanism I. American Mathematical Society. Retrieved on 2006-04-05.
a Shannon, Claude Elwood (1940). "A symbolic analysis of relay and switching circuits". Massachusetts Institute of Technology.
a Digital Equipment Corporation (1972). PDP-11/40 Processor Handbook (PDF), Maynard, MA: Digital Equipment Corporation.
a Verma, G.; Mielke, N. (1988). "Reliability performance of ETOX based flash memories". IEEE International Reliability Physics Symposium.
a Meuer, Hans; Strohmaier, Erich; Simon, Horst; Dongarra, Jack (2006-11-13). Architectures Share Over Time. TOP500

Designing Network Server

Network server is a most important component of a computer network because the entire computer network is administered, controlled and managed through it. Before designing a network server for your organization, you should have the adequate knowledge about the following things.

Server Processor

Processor is a heart of the CPU. It processes all the commands, instructions and commands and execute them to perform certain actions. Pentium processors are very reliable in performance and speed and trend is growing to use the multiprocessor servers to share the load on each processor. If one processor fails to work due to any reason, there is no effect on the other processor in the same server so it’s a wise decision of the network administrators to use the multiprocessor server for company’s network.

Hard Disk

Hard disks are used to store all the data in permanently. Hard disk is a mechanical device and while selecting the hard disk you should consider the S.M.A.R.T (Smart Monitoring and Reporting Technology). This technology monitors the hard drives and predicts the any failure in the hard drivers. Today, most of the server providers provide hot swap disk drives, this means that if one there is any error occurred in the hard drives, it can be replaced with the other hard drives while the server is in the working mode.

Clustering

In a clustering environment, two or more servers operate as a single server and the failure of the one server does not affect on the other servers. Clustered environment has the benefits such as high performance, reliability and load balancing.

Memory Performance

While selecting the physical memory for the server it should be considered the memory support Error Correcting Code technology. ECC technology fixes and repairs any single bit errors and report the multi bit errors. High memory is very vital for the server for its best performance, speed and continuous work.

Power Supply

Most of the computers come with the multi power supplies. This means in case of failure of the one power supply, does not affect on the other power supply in the same computer and in this way computer works normally. Multi power supplies are hot swappable like the hard disks i.e. faulty power supplies can be replaced with the new ones while the server is in the working mode.

UPS

UPS or uninterrupted power supply are very important in a network environment because a sudden jerk of the electricity may cause of the hard drives or mother boards of the server as well as the other computers in the network. A UPS normally provide a backup of 3-4 hours and during that time server and other computers can be setup and the files or other data can be saved.

Cooling Fans

The cooling system inside the server is provided by the cooling fans. Cooling fans pull the cool air inside the server and through out the heat from the server. The failure of the cooling fan results in the automatic shutdown of the server due to the high buildup of the heat. Many vendors of the computer systems are providing the hot swappable cooling fans.

Computer Monitoring Hardware

There is a specially designed adapter to monitor the performance of the different parts of the hardware of the computer. This adapter can also be controlled by a modem remotely.

Computer Monitoring Software

Different computer monitoring software is available in the market and their main purpose is to monitor the performance of the server and the client computers.

Data Server Location

Network server should be placed in a dust free, cooling capable and clean environment and only the authorized users should be allowed to enter in the server room.

Hopefully my above mentioned tips will help you building a better server for your computer network

B. Bashir manages this website Networking Tutorials and regularly writes articles on various topics such as Computer Networking, Network Troubleshooting Tips Wireless Networking, Computer Hardware, Certifications, How Tos, Network Security Guide and computer tips.

Welcome to Mobile Computing Networks

Using mobile computers when in transit implies mobile computing. This is effectuated by using wireless technologies such as LAN, WAN, Wi-Fi, GPRS, etc.

LAN refers to Local Area Networking. This is not a very mobile technology, as it restricts the area of its reach. LAN refers to the connectivity of two or more fixed or mobile computing devices within a particular area. This connection can be done physically by cables (in which case it would not be an example of mobile computing) or other connections such as infrared rays and wireless connections. LAN enables computers within its reach to share and compute data. It is primarily an intranet network.

WAN is Wide Area Networking. It is wider in its outreach. WAN refers to the connection of two locations. These locations may be connected internally through LAN networks. WAN essentially uses wireless connections between its locations.

MAN is another kind of network used in mobile computing. It stands for Metropolitan Area Networking and it connects mobile computing devices within a particular city or metropolitan area. Devices such as mobile phones and car computers can be hooked up onto MAN to keep them interconnected. MAN provides speeds of 128 kbps or 256 kbps. Cities such as New York, Philadelphia, Minnesota, Atlanta, Baltimore, Dallas and about 15 major airports in America are currently connected by MAN.

Cell phones are currently the most commonly used mobile computing devices on the planet. They use wireless technologies such as GSM, CDMA, WLL, GPRS, EDGE, 3G etc. for their connectivity. Currently, GPRS or General Packet Radio Service is considered a fast-growing technology. GPRS networks coupled with EDGE or Enhanced Data Rates for Global Evolution provide fast Internet connection on cell phones. They can provide data transfer speeds of about 384 kbps, which are much higher than GSM and CDMA technologies.

Besides these popular services, there are also some lesser-known networks that have been introduced lately. One such network, the Metricom, was available in 12 cities and 15 airports. However, it is no longer available due to the company’s financial constraints. ArrayComm and SWIFTComm are relatively new networks that promise speeds of up to 1 Mbps to the mobile computer user.

Mobile Computing provides detailed information on Mobile Computing, Mobile Computing Networks, Mobile Computing Solutions, Mobile Computing Devices and more. Mobile Computing is affiliated with Womens Laptop Cases.

Computer Network Devices And Component

A Computer network is comprised of different devices to share, transmit, and boost the signal, voice and data. Network devices or components are the physical parts connected to a network. There is a large number of the network devices and are increasing daily. The basic network devices are: Individual Computers, Server, Hub, Switch, Bridges, Routers, Modems, Printers, DSL Modems & Routers, Gateways, Network Interface Cards, Cabling & Wireless access point. The following is a overview of each of these network devices.

INDIVIDUAL COMPUTERS: The personal computer is usually a desktop computer, a work station or a laptop. The personal computers are most widely used in any organization or for personal use. The individual computers are the most common types of the microcomputers.

SERVER: A server is a computer on a network, which process request and is used to share the data and resources among the other computers in a network. A server stores all the necessary information and provides the different services like, workstation computer’s logon access, internet sharing, print sharing, disk space sharing etc. There are different types of servers e.g File and print server, database server, proxy server, Fax server, backup server etc. A database server stores all the data and software, which may related to the certain database and it allows other network devices to access and process the database queries. A file server is used to store the data of any user on the network and a print server manages one or more printers in a network. Similarly a network server is a server that manages the network traffic.

NETWORK INTERFACE CARD: Network interface cards are attached with the computer or other network devices and are used to provide the connectivity between the two computers. Each network card is specifically designed for the different types of the network like Ethernet, FDDI, Token Ring and Wireless Networks. The Network card operates on the first and second layers of the OSI models i.e Physical layer and datalink layer specifications. NIC basically defines the physical connection methods and the control signals that provides the timings of the data transfer over the network.

HUBS: Hub is a simplest network device. The function of the hub is broadcasting i.e data is forwarded towards the all ports of a hub, regardless of whether the data was intended for the particular systems in the network or not. Computers in a network are connected to a hub with a twisted pair (CAT5) cables. There are two types of the hubs. 1. Active Hubs. 2. Passive Hubs.

SWITCHING HUB: The Switching hub (also called “switch” is the most advance shape of the basic hub. In a basic hub all the computers are connected with the hub and the speed of the network is defined by the slowest computer network card connected. For example if you have 10/100 Mbps cards in a network and only one card of 10Mbps speed then the system cannot run faster than the 10 Mbps. Now if you have a switching hub in a network, it will allow all the faster connections in the network to remain at the higher speed and still interact with the 10Mbps system.

SWITCHES: Switch is a intelligence device than hub. Switch is a layer 2 device. Swith provides the same function as a hub or a bridge but it has the advance functionality of connecting the two computers together temporarily. Switch contains the switch matrix or switch fabric that can connect and disconnect ports. Unlike hubs, switch only transmit or forwards the data to the destined computer and it does not broadcasts the data to all its ports.

MODEMS: Modems are the devices, which are used to translate the digital data into the analog format and vice versa. It performs the two main functions. Modulation and demodulation. A modulated data can travel across the conventional telephone lines. The modem modulates the signals at the sending end and demodulates at the receiving end. Modems are required for different types of the access methods such ISDN, DSL and 56K data modem. Modem can be the internal devices that plug into the expansion slots in a system or can be external devices that plug into the serial or USB ports. In Laptops, PCMCIA cards are used for this purpose and many new laptops having the built in integrated modems. The specialized devices are designed for use in the systems such as handheld computers. In ISPs where the large scaled modems are required, rack-mounted modems are used.

ROUTERS: Routers route the data between two logically and physically different networks. A Router has the capability to determine the destination address for the data and hence provides the best way for the data to continue its journey. Router gets this capability through its software called routing software. Unlike Switches and Bridges, which use hardware configured MAC address to determine the destination of the data, router uses logical network address such as IP address to make the decision in determining the destination of the data.

GATEWAY: A gateway performs the function of translating the data from one format to another format without changing the data itself. A gateway can be a device, system, software. A computer with two NIC cards can function as a gateway. Router acts as a gateway e.g a router that routes the data from a IPX network to a IP network is technically a gateway. The same can be said of translational switch converts from a Ethernet network to a token ring network.

CABLES: There are two most common types of the cables. 1. 10baseT and 10base2. 10baseT is a four paired cable. 10baseT has further two types 1. UTP (unshielded twisted pair) and 2. STP (shielded twisted pair. STP is most secure cable covered with the silver coated twisted paper to protect the cable. On the other end Thin 10base2 looks like the copper coaxial cabling that often used to connect TV sets and VCR. 10baseT/Cat5 cables are most commonly used cables to connect the computers. It has the connector, (like a telephone connector) called RJ45 connector.

Twisted pair cables are ideal for the small, medium or large networks.
My recommendation for using cables for networking is to use 10baset/Cat5 cables

Submitted by:

Fiza http://www.theitlibrary.com

Computer Networking Solutions For Small Businesses

Many terms of the computer networking fundamentals for small businesses have come from the physical world of transportation. Some examples of such terms are ports, hubs, bridge, switching and routing. However, this simile is not unjustified because networks have same importance regarding the boom of the information era, as the transportation to the industrial era. Both computer networks and transportation system require very sound infrastructure.

Computer Networking is connecting the Computers: Most fundamental form of computer networking goes back to connecting any two electronic equipments for the transfer of data between them. Third equipment only helps the communication of data. However, connecting a printer to computer simply with the help of a USB cable is not called a network. It will be a part of the network if connected with router or switch. Advent of Internet has forced the most of the companies to think about the computer networking. No matter how small business you are running, you need to have computer-networking facilities for publicity, email and online marketing of your products and services. If you do not have a well-established network of computer, your competitors will leave you behind in contacting the prospective customers.

The Biggest Advantage is File Sharing: File sharing is perhaps the most talked about component of the computer networking fundamentals. File sharing is simply centralized grouping and organization of data files on a network server. Availability of all the data files at one place makes managing documents and data easier. Furthermore, you can also avoid the inconvenience caused by the inconsistant scheme of work among the different departments of the business. The newer versions of the network operating systems give tremendous control to the administrator. He is in complete control whether a person can get access to a particular file or not.

Sharing of Printers Saves Both Time and Money: Second important component of the computer networking fundamentals for small businesses is printer sharing. It saves a lot of money and time that you would have spent on the purchasing and maintenance of printers. The printers connected to the computer network have more features than those connected to single computers.

Email: One should also learn the importance of email to get the full understanding of computer networking fundamentals for small businesses. Group email facilitates fast and effective communication among the employees. Small business can also improve their scheduling, task assignment and contact management with the help of group or internal email. Moreover, in-house communication of documents is better than faxing because group emails are less expensive easier and unbelievably fast.

Alexander Gordon is a writer for http://www.smallbusinessconsulting.com - The Small Business Consulting Community. Sign-up for the free success steps newsletter and get our booklet valued at $24.95 for free as a special bonus. The newsletter provides daily strategies on starting and significantly growing a business.

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Computer Networking - How It Works

Computer networking is a process of sharing data and shared resources between two or more connected computers. The shared resources can include printer, Fax modem, Hard disk, CD - DVD Rom, Database and the data files. A computer network can be divided into a small or local area network, a networking between computers in a building of a office (LAN), medium sized network (MAN), a network between two offices in a city and Wide network (WAN) a network between the computers, one is locally and the other can be thousands of miles away in any other country of the world.

WAN connectivity is achieved by a network device known as “Router”. The internet is the world’s largest WAN network, where millions of computers from all over the globe and connected with each other.

Networking is the practice of linking two or more computers or devices with each other. The connectivity can be wired or wireless. A computer network can be categorized in different ways, depends on the geographical area as mentioned above.

There are two main types of the computer network client-server and peer to peer. In the client server computing, a computer plays a major role known as server, where the files, data in the form of web pages, docs or spread sheet files, video, database & resources are placed.

All the other computers in the client/server network are called clients and they get the data from the server. In the peer to peer network all the computers play the same role and no computer act as a centralized server. In the major businesses around the world client-server network model is in major use.

A network topology defines the structure, design or layout of a network. There are different topologies like bus, ring, star, mesh, hybrid etc. The star topology is most commonly used network topology. In the star topology, all the computers in the network are connected with a centralized device such as hub or switch. Thus forms a star like structure. If the hubs/switch fails to work for any reason then all the connectivity and communication between the computers of a network will be halted.

In the network, a common communication language is used by the computers and the network devices and this language is known as protocols. The most commonly used and popular protocols on the internet and in the home and other networks is called TCP/IP. TCP/IP is not a singleprotocol but it is a suite of several protocols.

A network can be a wired or wireless and TCP/IP protocol can work both in types of network.

A data flow in a computer network can be divided into seven logical layers called OSI layersmodel that was developed by Intel and Xerox Corporation and was standardized by ISO.

1. Application layer
2. Presentation layer
3. Session layer
4. Transport layer
5. Network layer
6. Data Link layer

a. Media access control sub-layer

b. Logical link control sub-layer
7. Physical layer.

A network can be divided into different scales and ranges and it depends on the requirement of the network and the geographical location. Computer Network can be divided into Local Area Network, Personal Area Network, Campus Area Network, Wireless Local Area Network,Metropolitan Area Network and Wide Area Network.

There are several network connection methods like HomePNA, Power line communication, Ethernet and Wifi connection method.A network can also be categorized into several different types based on the services it provides like Server farms, Storage area networks, Value control networks, Value-Added networks,SOHO network, Wireless network and Jungle networks.

B. Bashir manages this website Networking Tutorials and regularly writes articles on various topics such as Computer Networking Network Troubleshooting Tips Wireless Networking, Computer Hardware, Certifications, How Tos, Network Security Guide and computer tips.

 

Networking For LAN

Wiring up a LAN (local area network) can be very easy, or it can be very difficult – it all depends on the size of your network, and how you’re trying to go about it.

For a very small home network, you can get by without using any special equipment except the wires. If you want to use a network to share Internet access or a printer, just plug an Ethernet cable into the computers you want to network, and then use the simple networking features that are built into Windows, such as Internet Connection Sharing. This approach has many downsides, though – you’ll need an extra Ethernet card in each computer for every extra computer you connect to the network, for one.

Instead of connecting each computer to the next, it is better to simply connect all the computers to a central router. This is a very efficient way of connecting computers together, as the data you send will be quickly and easily routed to its destination: the data goes to the router, which knows which wire to send it down for it to reach the destination address, and simply sends it that way. This also allows you to turn on and off computers as you please with no ill effects, as the router is always-on.

If you want to connect more devices to the network than the four or five ports on a router will allow, then you need to get a network switch. This allows you to create a separate sector of your network especially for one group of devices. For example, you might have your computer and your printer both plugged into a switch. The computer and the printer can then communicate between themselves without the data needing to travel out onto the wider network – but if they want to send to or receive from the wider network, they can do that too.

John Gibb is the owner of ethernet resources For more information on ethernet check out http://www.ethernet-intelligence.info

CSI* - Computer Forensics Files: Real Cases from Burgess Forensics #12

Computers,Law

The Case of the Computer That Got Lost

The stories are true; the names and places have been changed to protect the potentially guilty.

A few years ago, Debby Johnson, an attorney from a large firm based in Kansas City, contacted me about a relatively simple matter. I was to travel to offices in Sacramento from my San Francisco-area labs, copy a computer's disk drive, and locate emails sent by the plaintiff to his brothers and sisters, of which he had nine. The case was a product liability lawsuit for an amount in the tens of millions of dollars. The plaintiff claimed that his health had been damaged by an international firm's defective product, although he was symptom-free at the moment. What was the product? Let's say it was coffee.

From the cool Bay Area in summer, I traveled to downtown Sacramento, where it was a balmy 106 degrees. I knew I was sweating, but inside I was cool. I wondered if someone else would be in hot water soon.

It is not unusual for me to never meet my client, for computers can be shipped to me at my lab, but Debby was there in the law offices of the plaintiff's attorney. In an oak-paneled conference room we met with counsel for "the other side" and with the plaintiff himself. He sat smugly with his shiny computer on the conference table, friendly enough in spite of his contention that I would never find the offending emails he had allegedly sent years before. My client believed that this fellow had sent emails to his siblings that would disprove his contention - that would show him to be making up a case to snag a cool few ten millions.

I removed the hard disk from our man's system to make a forensic copy to work with and analyze. I was surprised to find that the hard disk was 100GB in size. A drive of that capacity was fairly new and unusual to see in a case this soon after it had come on the market. I was prepared for a much smaller disk drive, as I had been told I'd be seeing one about 20% the size. Fortunately, there was an electronics superstore nearby, so I doffed my suit jacket, cranked up the air conditioning on my minivan / lab wagon (that beauty just turned over 200,000 miles on the day I'm writing this), and headed on over for a bit of new gear. Forty-five minutes and a bit of melted rubber later I arrived back at the scene to forensically clean the new disk drive by writing zeroes to every sector..

Once cleared to my satisfaction, I set up the copy process. In those days, while I was partial to Diskology's Disk Jockey, the version I had then didn't seem to be able to handle what was such a large drive for the time. I probably used Byte Back on a forensic Intel box I had brought just in case. I began the copy process and it went without a hitch. But while the copy was proceeding, I began to wonder - wasn't this a pretty big drive to have been around at the time of the alleged emails? And for that matter, wasn't this computer pretty fast for its age. And did Windows XP really come on the market before these emails were to have been written? I was beginning to suspect that the game was rigged, and that I never would find the plaintiff's deleted emails on that computer.

I discussed the matter with Debby. I guessed that the plaintiff was right about the task being futile - because I guessed that the offending emails were never on this computer. I said I'd be willing to look for them, but I didn't want to waste my client's cash. Debby asked me to look into the matter of the components' age when I got back to HQ. A few inquiries with the manufacturer and a couple of Google searches later, I was pretty well convinced that the fellow had never written those emails on this computer. Windows XP was almost too new, the disk drive was a couple of weeks too modern, and the computer was a month or two younger than those emails.

Debby called opposing counsel - who had no idea why this might not be the original system…until he checked with his man. Turns out he had "set it on the curb for trash pickup" because it "wasn't working." The attorneys weren't happy. The court wasn't happy. The only solution was for me to go to the nine brothers and sisters in four states to copy their personal computers and sift through those for the offending emails.

Do you think they were happy to hear from me? Would you be if your brother put you on the spot like that? Each of them had to agree that a perfect stranger - one who was working against their beloved brother - could come into their homes and look through everything on their personal computers. The most telling example of their displeasure was from one brother, a former Viet Name-era Green Beret, who - in response to my phone call asking when would be a good time to show up - said "I didn't spend two years marching up and down the God**m Ho Chi Minh Trail for this s**t!" I understood.

It turns out that opposing counsel had never gotten around to telling this group that a computer forensics guy would be calling them and they needed to cooperate. I found that out when I told Debby of the righteous resistance I had come up against. She straightened it out with counsel and the next set of phone calls I made to the sibs was a lot more congenial.

The next several days, traveling from state to state, town to town, brother to sister to brother and on and on to copy the private data of nine innocent family members had its challenges. But that's a story unto itself…I'll spare you most of the details. Upon my return, the protocol called for me to search all of the data for any correspondence from - let's call him "The Brother" that referenced his struggles with … we're calling it Coffee. I was then to print out the references I found, and send a copy both to the judge and to opposing counsel for privilege and relevance review. Debby and her firm were not to get a look at the data until anything either private or irrelevant had been picked out, and only the remainder produced.

What did I find? Around the time of the alleged emails, lo and behold, I found actual emails. The whole family was talking about The Brother's struggle with Coffee, their individual investigations into Coffee, and the upcoming lawsuit about Coffee. At one point, one email pointed out that this guy Burgess was going to be looking into everyone's email, and wouldn't it make sense not to talk about Coffee? They agreed. They now spoke only of … "the C-Word."

What else did I find when I performed my electronic discovery and digital forensic analysis? Well, for the most part, I just can't talk about it. There are some things on your computer you wouldn't want me talking about, I'm sure. There are things on my computer I wouldn't want me talking about either! E-discovery often has to be a pretty private process.

But there was one particularly interesting finding. When I called the Green Beret Brother (GBB) from his sister's place across town, and asked for permission to head on over to make the copy of his computer, he obligingly told me it was okay. When I got there, he first asked me to read and sign a statement that I wouldn't hold him liable for any damage to me or my equipment - unintentional or otherwise. Well that was a little scary coming from a guy trained in the arts of stealth, war, and undoubtedly the garrote. But as the paper didn't seem like a legal document, I signed it, if that was what would get me in to do my work. He was pleasant enough, the music he had on was good, and the copy went without a hitch. And I left alive and undamaged - a plus, indeed!

Once in my lab, I discovered the last thing that had happened on his computer. About one minute after my phone call for permission to go over, GBB had sent himself an email and then immediately deleted it. The subject, all in caps, was "COFFEE!" No "C-Word" fooling around for him. The message in the body was simple and succinct: "If you find this email, F*** YOU!!!!!" It's nice when a person knows how he feels and is able to express it freely. There was also a deleted photograph attached to the deleted email. Upon recovering same, it turned out to be a very recent photo of an extended middle finger - presumably GBB's finger. Visual aids are always helpful in understanding the subject matter, don't you think?

In the end, I produced about 75 pages of documentation I thought relevant. Of course, I had to include GBB's missive. As expected opposing counsel called everything irrelevant or privileged. Also as expected, the judge allowed all of the documents I had produced - with a number of lines redacted - to be delivered to my client. Everyone's favorite was the literate bit produced by GBB.

As for The Brother - the court decided that not only was he not very honest, due to the destruction of the most important data in the case - his original computer - but the evidence and the relevant emails showed him to be apparently undamaged by the Coffee. The case went to defeat, Debby and her firm were happy, and GBB became a legend.

This is just one of the many "CSI* - Computer Forensics Files: Real Cases from Burgess Forensics". Stay tuned for more stories of deceit uncovered by computer forensics.

*The Free Dictionary lists more than 160 definitions for CSI at acronyms.thefreedictionary.com. We choose Computer Scene Investigation.

Steve Burgess is a freelance technology writer, a practicing computer forensics specialist as the principal of Burgess Forensics, a highly regarded expert witness, and a contributor to the just-released Scientific Evidence in Civil and Criminal Cases, 5th Edition by Moenssens, et al. Mr. Burgess may be reached at http://www.burgessforensics.com - email: steve@burgessforensics.com



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