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 may run from just a few instructions to many millions of instructions, as in a program for a word processor or a web browser. A typical modern computer can execute billions of instructions per second (gigahertz or GHz) and rarely make a mistake over many years of operation. Large computer programs consisting of several million instructions may take teams of programmers years to write, and due to the complexity of the task almost certainly contain errors.

Errors in computer programs are called "bugs". Bugs may be benign and not affect the usefulness of the program, or have only subtle effects. But in some cases they may cause the program to "hang"—become unresponsive to input such as mouse clicks or keystrokes, or to completely fail or "crash". Otherwise benign bugs may sometimes may be harnessed for malicious intent by an unscrupulous user writing an "exploit"—code designed to take advantage of a bug and disrupt a program's proper execution. 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.^[15]

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,^[16] 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. For instance, 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.^[17]

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.^[18] 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 presents a significant intellectual challenge. Producing software with an acceptably high reliability within a predictable schedule and budget has historically been difficult; the academic and professional discipline of software engineering concentrates specifically on this problem.

Acer Laptop

When Acer laptop computers first appeared onto the UK laptop scene, people tended to turn up their nose at the name (it was not a known brand) and because Acer laptop computers were significantly cheaper than many of their rivals, the assumption was made, quite wrongly, that cheaper laptops meant shoddy laptops.

Over the years people who have tried Acer laptop products have discovered that a cheap Acer laptop computer means a laptop that costs less but does not provide a sub standard set of components.

The Acer company goal is to provide people with an easy to use laptop, which is dependable and satisfies customer requirements and was, obviously, affordable. This ethos has turned Acer laptops from being "Oh dear, you own an Acer" to becoming one of the top five PC vendors in the world and in 2008 became world's No.1 for their notebook computers. Laptop snobs should beware of turning their noses up at Acer laptops nowadays, they may, very well, be missing something.

The Acer Aspire laptop 5735 has Acer Cine Crystal which means you get to near cinema quality viewing on the High Definition TFT LCD 15.6" screen and with its stereo speakers you can look forward to unbelievable sound quality, too. The 2.0 GHz Intel Core Duo processors makes downloading quicker and completing tasks becomes a piece of cake. With 4GB of RAM and 250 GB Hard drive storage, you are not going to run out of space any time soon. The Aspire laptop is wireless enabled, so, you are ready to surf the web and its 5-in-1 card reader makes file sharing easy peasy, too. The Acer Aspire 5735, a What Laptop Gold Award winning laptop computer for 2009, comes with Microsoft Vista Home Premium operating system and is an excellent multimedia laptop for home use.

Pyramid.com like to think they know a bit about laptop computers and can readily tell the difference between an inexpensive laptop computer and a cheap laptop computer. Pyramid.com stock and supply Acer laptop computers for home, school or business use, which would allow you to benefit from all the latest laptop technology at a fraction of the price.

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Tips When Getting Affordable Web Hosting

Web hosting is an essential aspect in running an online business. Since you would need a fully functional website, which you can use as your online shop, you will also consequently require the right web host. If you think that web hosting services need to be expensive, think again. Almost everyone is now able to get affordable web hosting services from the right providers.

However, not every cheap hosting company is worthy of your trust and your money, so you still need to find the right company for you. There are also hosting reviews found on the web that can help you refine your search further. Getting the hosting service perfect for your budget is important, but there are a few things you need to remember if you plan on getting the cheaper types of hosting.

When settling for affordable web hosting, you should not compromise on reliability. You may opt for the cheapest service there is, and consequently save on costs big time, but if you don't have a reliable provider, the losses incurred by your web business could be devastating. You would not want a web host who opts to stay invisible, especially during downtimes. If you can find a cheap web host who can guarantee fast and efficient reliability 24/7, then you know you have worth keeping.

Along with reliability, your affordable web host needs to be able to provide excellent technical support tools. They should have a stand-by help desk support system, which is prepared to assist the clients anytime needed. When choosing affordable web hosting, you should go for a hosting provider who can answer your verifications truthfully and thoroughly.

There are cheap web hosts that offer substandard services in exchange for very low monthly rates. You need to avoid these so-called providers. One of the more important things to establish when choosing a web host is the uptime guarantee provided. If the inexpensive web hosting solution does not provide an uptime guarantee of 99%, it's best to look elsewhere. Surely, you would not want your website to be inaccessible to millions of potential site visitors worldwide.

If the web hosting company has been in the business for a long time, you can be assured that they are doing their job well. However, you also need to look into the background of any hosting provider before making any choice. If you can solicit reviews and comments from people in the web hosting industry, this can be extremely helpful.

Since you are searching for affordable web hosting, make sure that the fees being offered are definitely affordable. The fees can go to as low as $1 and as high as $10, but not higher. You can determine the fees you are most comfortable with after considering your budget and the requirements of your website. Getting cheap web hosting will allow you to limit your expenses as you are growing your online business.

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